Merge remote-tracking branch 'upstream/client-side-tests' into io-streams-enhance

# Conflicts:
#	src/logic/scripting/descriptors_manager.cpp
#	src/logic/scripting/descriptors_manager.hpp

dev/tests/io_stream.lua

@@ -0,0 +1,34 @@
+local device = file.create_memory_device()
+file.write(device..":test.txt", "Hello\nWorld")
+file.write_bytes(device..":test.bin", Bytearray({20, 30, 100, 200, 255}))
+
+local stream = file.open(device..":test.txt", 'r')
+
+local line1 = stream:read_line()
+local line2 = stream:read_line()
+
+assert(line1 == "Hello")
+assert(line2 == "World")
+
+local stream2 = file.open(device..":test.bin", 'rb')
+local data = stream2:read(5)
+assert(data[1] == 20)
+assert(data[2] == 30)
+assert(data[3] == 100)
+assert(data[4] == 200)
+assert(data[5] == 255)
+
+local stream3 = file.open(device..":test.txt", 'r')
+assert(stream3:is_alive())
+stream3:close()
+assert(not stream3:is_alive())
+
+local stream4 = file.open(device..":test.txt", 'r')
+stream4:seek('b', 6)
+local line = stream4:read_line()
+assert(line == "World")
+
+local stream5 = file.open(device..":test.txt", 'r')
+stream5:seek('e', 0)
+local pos = stream5:tell()
+assert(pos == 11)

doc/en/scripting.md

@@ -42,6 +42,7 @@ Subsections:
     - [utf8](scripting/builtins/libutf8.md)
     - [vec2, vec3, vec4](scripting/builtins/libvecn.md)
     - [world](scripting/builtins/libworld.md)
+- [Extensions for standard libraries](scripting/extensions.md)
 - [Module core:bit_converter](scripting/modules/core_bit_converter.md)
 - [Module core:data_buffer](scripting/modules/core_data_buffer.md)
 - [Module core:vector2, core:vector3](scripting/modules/core_vector2_vector3.md)

doc/en/scripting/extensions.md

@@ -0,0 +1,204 @@
+# Standard Library Extensions
+
+The **stdmin.lua** kernel script defines functions that extend and complement some of the standard **Lua** libraries.
+
+## Contents:
+- [table extensions](#table-extensions)
+- [string extensions](#string-extensions)
+- [math extensions](#math-extensions)
+- [bit extensions](#bit-extensions)
+- [additional global functions](#additional-global-functions)
+
+## Table Extensions
+```lua
+-- Creates and returns a copy of the given table by creating a new one and copying all elements from the given table into it.
+table.copy(t: table) -> table
+
+-- The deep copy function creates a full copy of the source table, including all its subtables. 
+table.deep_copy(t: table) -> table
+
+-- Returns the number of pairs in the given table.
+table.count_pairs(t: table) -> int
+
+-- Returns one element from the given table at a random position.
+table.random(t: table) -> any
+
+-- Returns true if x is contained in t.
+table.has(t: table, x: any) -> boolean
+
+-- Returns the index of x in t. If the given object is not contained in the table, the function returns -1.
+table.index(t: table, x: any) -> int
+
+-- Removes element x from t.
+table.remove_value(t: table, x: any)
+
+-- Shuffles values ​​in the table.
+table.shuffle(t: table) -> table
+
+-- Adds values ​​from table t2 to table t1. If table t2 contains a key from t1, the key's value will not be changed.
+table.merge(t1: table, t2: table) -> table
+
+-- Iterates through the table and applies a func to all its elements, returning the new value of the element.
+table.map(t: table, func: function(indx, value)) -> table
+
+-- Iterates through the table using a func that returns true if the element should be kept and false if it should be deleted.
+table.filter(t: table, func: function(indx, value)) -> table
+
+-- Allows you to safely retrieve the value for the specified key. If the key exists in the table, the method will return its value.
+-- If the key is missing, the method will set it to the default value and return it.
+table.set_default(t: table, key: int | string, default: any) -> any
+
+-- Returns a "flattened" version of the original table.
+table.flat(t: table) -> table
+
+-- Returns a deep "flat" version of the original table.
+table.deep_flat(t: table) -> table
+
+-- Returns a truncated version of the table from index start to index stop, inclusive. Key-value pairs
+-- are not preserved in the new table. For nil values, the value starts at 1 and ends at #arr, respectively.
+table.sub(arr: table, start: number | nil, stop: number | nil) -> table
+
+-- Adds a value to the table only if it was not originally there.
+table.insert_unique(t: table, val: any)
+table.insert_unique(t: table, pos: int, val: any)
+
+-- Returns a table containing all keys of the given table, including numeric ones. table.keys(t: table) -> table
+
+-- Adds all key-value pairs from table extension to table t. If a key from t is present in extension, its value will be overwritten.
+table.extend(t: table, extension: table) -> table
+
+-- Converts the passed table to a string.
+table.tostring(t: table) -> string
+```
+
+## String extensions
+
+It's important to note that all of the functions listed below that extend **string** can be used as meta-methods on string instances, i.e.:
+
+```lua
+local str = "ABA str BAB"
+
+if str:starts_with("ABA") and str:ends_with("BAB") then
+print(str:replace("BA", "DC"))
+end
+```
+
+```lua
+-- Splits the string into parts based on the specified separator/expression and returns the result as a table of strings. If withpattern is true, the separator parameter will be evaluated as a regular expression. string.explode(separator: string, str: string, withpattern: boolean) -> table<string>
+
+-- Splits the string into parts based on the specified delimiter and returns the result as a table of strings.
+string.split(str: string, delimiter: string) -> table<string>
+
+-- Escapes special characters in the string, such as `()[]+-.$%^?*`, into `%character` format. The `NUL` character (`\0`) will be converted to `%z`.
+string.pattern_safe(str: string) -> string
+
+-- Splits seconds into hours, minutes, and milliseconds and formats them using the following parameter order: `minutes, seconds, milliseconds`, and then returns the result. If format is not specified, it returns a table where:
+-- h - hours,
+-- m - minutes,
+-- s - seconds,
+-- ms - milliseconds.
+string.formatted_time(seconds: number, format: string) -> string | table
+
+-- Replaces all substrings in str equal to tofind with toreplace and returns a string with all the modified substrings.
+string.replace(str: string, tofind: string, toreplace: string) -> string
+
+-- Removes all characters equal to char from the string from the left and right ends and returns the result.
+-- If the char parameter is undefined, all empty characters will be selected.
+string.trim(str: string, char: string) -> string
+
+-- Removes all characters equal to char from the string from the left end and returns the result.
+-- If the char parameter is undefined, all empty characters will be selected.
+string.trim_left(str: string, char: string) -> string
+
+-- Removes all characters equal to char from the right end of the string and returns the result.
+-- If the char parameter is undefined, all empty characters will be selected.
+string.trim_right(str: string, char: string) -> string
+
+-- Returns true if the string begins with the substring start.
+string.starts_with(str: string, start: string) -> boolean
+
+-- Returns true if the string ends with the substring endStr.
+string.ends_with(str: string, endStr: string) -> boolean
+
+-- The string.lower and string.upper functions are also overridden by utf8.lower and utf8.upper.
+
+-- Escapes a string. It is an alias for utf8.escape.
+string.escape(str: string) -> string
+
+-- Escapes special XML characters. An alias for utf8.escape_xml.
+string.escape_xml(text: string) -> string
+
+-- Adds a char to the left and right of the string until its size equals size.
+-- By default, char is equal to the space character.
+string.pad(str: string, size: int, char: string) -> string
+
+-- Adds a char to the left of the string until its size equals size.
+-- By default, char is equal to the space character.
+string.left_pad(str: string, size: int, char: string) -> string
+
+-- Adds a char to the right of the string until its size equals size.
+-- By default, char is equal to the space character.
+string.right_pad(str: string, size: int, char: string) -> string
+```
+
+## Math extensions
+
+```lua
+-- Returns _in if it is in the range low <= _in <= high
+-- Otherwise, returns the boundary to which _in is closest.
+math.clamp(_in: number, low: number, high: number) -> number
+
+-- Returns a random fractional number in the range low to high.
+math.rand(low: number, high: number) -> number
+
+-- Returns the normalized value of num relative to conf.
+math.normalize(num: number, [optional] conf: number) -> number
+
+-- Returns the rounded value of num to the specified number of decimal places.
+math.round(num: number, [optional] places: number) -> number
+
+-- Returns the sum of all received arguments. If a table was passed as an argument, the method will return the sum of all its elements.
+math.sum(x: number, ... | t: table) -> number
+
+```
+
+## Bit extensions
+```lua
+
+-- Common arguments:
+-- * expr: A string containing a bitwise expression, conforming to the Lua 5.3 bitwise operations format
+-- * args: A list of names of the expression arguments. If nil, the list is automatically generated based on the detected identifiers.
+
+- Compiles the function to perform bitwise operations
+-- * asFunction: If true, returns the function; otherwise, returns a string of function code
+bit.compile(expr: string, args: table | nil, asFunction: boolean=true) -> function | string
+
+-- Compiles the function to perform bitwise operations and executes it in place
+-- * ...: Values ​​to be passed to the compiled function. bit.execute(expr: string, args: table | nil, ...) -> number
+```
+## Additional Global Functions
+
+This script also defines other global functions that are available for use. Their list is below.
+
+```lua
+-- Returns true if the passed table is an array, that is, if each key is an integer greater than or equal to one
+-- and if each key follows the previous one.
+is_array(x: table) -> boolean
+
+-- Splits the path into two parts and returns them: the entry point and the file path.
+parse_path(path: string) -> string, string
+
+-- Calls the function func iters times, passing it the arguments ..., and then prints to the console the time in microseconds that has elapsed
+-- since the call to timeit. timeit(iters: int, func: function, ...)
+
+-- Causes the coroutine to pause until the number of seconds specified in timesec has elapsed.
+-- The function can only be used inside a coroutine.
+sleep(timesec: number)
+
+-- Waits for the passed coroutine to complete, returning the control flow. The function can only be used inside a coroutine.
+-- Returns values ​​similar to those returned by pcall.
+await(co: coroutine) -> result, error
+
+-- A constant storing the PID of the current engine instance.
+os.pid -> number
+```

doc/ru/scripting/extensions.md

@@ -7,7 +7,7 @@
 - [расширения для string](#расширения-для-string) 
 - [расширения для math](#расширения-для-math)
 - [расширения для bit](#расширения-для-bit)
-- [Дополнительные глобальные функции](#дополнительные-глобальные-функции)
+- [дополнительные глобальные функции](#дополнительные-глобальные-функции)
 
 ## Расширения для table
 ```lua
@@ -62,6 +62,12 @@ table.sub(arr: table, start: number | nil, stop: number | nil) -> table
 table.insert_unique(t: table, val: any)
 table.insert_unique(t: table, pos: int, val: any)
 
+-- Возвращает таблицу, содержащую все ключи переданной таблицы, включая числовые.
+table.keys(t: table) -> table
+
+-- Добавляет в таблицу t все пары ключ-значение из таблицы extension, при этом если в extension присутствует ключ из t, то его значение будет перезаписано.
+table.extend(t: table, extension: table) -> table
+
 -- Конвертирует переданную таблицу в строку.
 table.tostring(t: table) -> string
 ```
@@ -200,4 +206,4 @@ await(co: coroutine) -> result, error
 
 -- Константа, в которой хранится PID текущего инстанса движка.
 os.pid -> number
-```
+```

res/layouts/ingame_chat.xml.lua

@@ -19,7 +19,7 @@ local function update_line(line, uptime)
     end
 end
 
-events.on("core:chat", function(message)
+local core_chat_handler = events.on("core:chat", function(message)
     while #lines >= max_lines do
         document[lines[1][1]]:destruct()
         table.remove(lines, 1)
@@ -36,7 +36,7 @@ end)
 function on_open()
     if not initialized then
         initialized = true
-        
+
         document.root:setInterval(1/animation_fps * 1000, function ()
             local uptime = time.uptime()
             for _, line in ipairs(lines) do
@@ -52,3 +52,7 @@ function on_open()
         end)
     end
 end
+
+function on_destroy()
+    events.remove("core:chat", core_chat_handler)
+end

res/modules/internal/debugging.lua

@@ -148,3 +148,29 @@ function error(message, level)
     end
     __error(message, level)
 end
+
+local LoggerClass = {
+    __index = {
+        info = function (self, text)
+            debug.log(string.format("[%s] %s", self.name, text))
+        end,
+        warning = function (self, text)
+            debug.warning(string.format("[%s] %s", self.name, text))
+        end,
+        error = function (self, text)
+            debug.error(string.format("[%s] %s", self.name, text))
+        end
+    }
+}
+
+local _getinfo = debug.getinfo
+
+function debug.Logger(name)
+    if not name then
+        local source = _getinfo(2, "S").source
+        name = file.remove_ext(source)
+    else
+        name = string.format("%s:%s", file.prefix(_getinfo(2, "S").source), name)
+    end
+    return setmetatable({name=name}, LoggerClass)
+end

res/modules/internal/events.lua

@@ -14,6 +14,7 @@ function events.on(event, func)
         events.handlers[event] = {}
     end
     table.insert(events.handlers[event], func)
+    return func
 end
 
 function events.reset(event, func)
@@ -24,6 +25,14 @@ function events.reset(event, func)
     end
 end
 
+function events.remove(event, handler)
+    local handlers = events.handlers[event]
+    if not handlers then
+        return
+    end
+    table.remove_value(handlers, handler)
+end
+
 function events.remove_by_prefix(prefix)
     for name, handlers in pairs(events.handlers) do
         local actualname = name

res/modules/internal/extensions/file.lua

@@ -23,6 +23,10 @@ function file.parent(path)
     return dir
 end
 
+function file.remove_ext(path)
+    return string.format("%s/%s", file.parent(path), file.stem(path))
+end
+
 function file.path(path)
     local pos = path:find(':')
     return path:sub(pos + 1)

res/modules/internal/extensions/table.lua

@@ -59,11 +59,7 @@ end
 
 function table.extend(t1, t2)
     for i, v in pairs(t2) do
-        if type(i) == "number" then
-            t1[#t1 + 1] = v
-        else
-            t1[i] = v
-        end
+        t1[i] = v
     end
 
     return t1
@@ -201,3 +197,11 @@ function table.tostring(t)
     end
     return s..']'
 end
+
+function table.keys(t)
+    local keys = {}
+    for key, _ in pairs(t) do
+        table.insert(keys, key)
+    end
+    return keys
+end

res/modules/internal/gui_util.lua

@@ -77,15 +77,18 @@ function Element.new(docname, name)
 end
 
 -- the engine automatically creates an instance for every ui document (layout)
-local Document = {}
-function Document.new(docname)
-    return setmetatable({name=docname}, {
-        __index=function(self, k)
-            local elem = Element.new(self.name, k)
-            rawset(self, k, elem)
-            return elem
+local Document = {
+    __index=function(self, k)
+        if type(k) ~= "string" then
+            error("element id is not a string")
         end
-    })
+        local elem = Element.new(self.name, k)
+        rawset(self, k, elem)
+        return elem
+    end
+}
+function Document.new(docname)
+    return setmetatable({name=docname}, Document)
 end
 
 local RadioGroup = {}

res/modules/internal/stream_providers/file.lua

@@ -4,16 +4,27 @@ local lib = {
     read = file.__read_descriptor,
     write = file.__write_descriptor,
     seek = file.__seek_descriptor,
+    tell = file.__tell_descriptor,
     flush = file.__flush_descriptor,
     available = file.__available_descriptor,
     is_alive = file.__has_descriptor,
     close = file.__close_descriptor
 }
 
+local __open_descriptor = file.__open_descriptor
+file.__open_descriptor = nil
+file.__read_descriptor = nil
+file.__write_descriptor = nil
+file.__seek_descriptor = nil
+file.__tell_descriptor = nil
+file.__flush_descriptor = nil
+file.__has_descriptor = nil
+file.__close_descriptor = nil
+
 return function(path, mode)
     return io_stream.new(
-        file.__open_descriptor(path, mode),
+        __open_descriptor(path, mode),
         mode:find('b') ~= nil,
         lib
     )
-end
+end

res/modules/internal/test.lua

@@ -0,0 +1,139 @@
+local __app = __vc_app
+
+local function get_node_center(node)
+    local pos = node.wpos
+    local size = node.size
+    return pos[1] + size[1] / 2, pos[2] + size[2] / 2
+end
+
+local function types_check_enum(value, enum)
+    if value == nil then
+        return true, nil
+    end
+    if type(value) ~= "string" then
+        return false, string.format("string expected [%s]", table.concat(table.keys(enum), "|"))
+    end
+    return true, nil
+end
+
+local function types_check_number(value)
+    if value == nil then
+        return true, nil
+    end
+    local value_type = type(value)
+    if value_type ~= "number" then
+        return false, string.format("number expected, got %s", value_type)
+    end
+end
+
+local function check_option(t, key, func, ...)
+    local value = t[key]
+    if value == nil then
+        return nil
+    end
+    local success, message = func(value, ...)
+    if not success then
+        error(string.format("invalid option '%s': %s", key, message))
+    end
+end
+
+local buttons_enum = {
+    left = 0,
+    right = 1,
+    middle = 2,
+}
+local no_options = {}
+
+local _tick = __app.tick
+local _set_button_pressed = test.set_button_pressed
+local _set_key_pressed = test.set_key_pressed
+local _enter_text = test.enter_text
+test.set_button_pressed = nil
+test.set_key_pressed = nil
+test.enter_text = nil
+
+function test.click(node, options)
+    options = options or no_options
+
+    check_option(options, 'button', types_check_enum, buttons_enum)
+    check_option(options, 'timeout', types_check_number)
+
+    local button = buttons_enum[options.button or 'left']
+    local timeout = options.timeout or 1000
+
+    local tm = time.precise_time()
+    while (time.precise_time() - tm) * 1000 < timeout do
+        if node.exists then
+            break
+        end
+        _tick()
+    end
+    if not node.exists then
+        error(string.format("timeout %s ms exceeded: element %s does not exists",
+            math.floor(timeout), string.escape(rawget(node, 'name'))))
+    end
+
+    local center_x, center_y = get_node_center(node)
+    _set_button_pressed(button, center_x, center_y, true)
+    _tick()
+    _set_button_pressed(button, center_x, center_y, false)
+    _tick()
+end
+
+-- TODO: replace with resolving in C++ side
+function test.find_by_attr(node, attr, value)
+    if getmetatable(node) == Document then
+        return test.find_by_attr(node.root, attr, value)
+    end
+    if node[attr] == value then
+        return node
+    end
+    local i = 1
+    while true do
+        local subnode = node[i]
+        if subnode == nil then
+            break
+        end
+        local found = test.find_by_attr(subnode, attr, value)
+        if found then
+            return found
+        end
+        i = i + 1
+    end
+end
+
+function test.find_by_text(node, text)
+    return test.find_by_attr(node, "text", text)
+end
+
+function test.find_by_attr_presence(node, attr)
+    if node[attr] then
+        return node
+    end
+    local i = 1
+    while true do
+        local subnode = node[i]
+        if subnode == nil then
+            break
+        end
+        local found = test.find_by_attr_presence(subnode, attr)
+        if found then
+            return found
+        end
+        i = i + 1
+    end
+end
+
+function test.fill(node, text, options)
+    test.click(node, options)
+    __app.tick()
+    _enter_text(text)
+    test.press("enter")
+end
+
+function test.press(key)
+    _set_key_pressed(key, true)
+    __app.tick()
+    _set_key_pressed(key, false)
+    __app.tick()
+end

res/modules/io_stream.lua

@@ -388,6 +388,10 @@ function io_stream:seek(mode, offset)
     self.ioLib.seek(self.descriptor, mode, offset)
 end
 
+function io_stream:tell()
+    return self.ioLib.tell(self.descriptor)
+end
+
 function io_stream:is_alive()
     return self.ioLib.is_alive(self.descriptor)
 end
@@ -414,4 +418,4 @@ function io_stream:flush()
     if self.flushMode ~= FLUSH_MODE_ONLY_BUFFER then self.ioLib.flush(self.descriptor) end
 end
 
-return io_stream
+return io_stream

res/scripts/stdlib.lua

@@ -127,6 +127,10 @@ require "core:internal/extensions/inventory"
 asserts = require "core:internal/asserts"
 events = require "core:internal/events"
 
+if test then
+    require "core:internal/test"
+end
+
 function pack.unload(prefix)
     events.remove_by_prefix(prefix)
 end

src/audio/audio.cpp

@@ -173,6 +173,12 @@ void audio::initialize(
         logger.info() << "initializing NoAudio backend";
         backend = NoAudio::create().release();
     }
+    if (settings.inputDevice.get() == "auto") {
+        auto inputDevices = audio::get_input_devices_names();
+        if (!inputDevices.empty()) {
+            settings.inputDevice.set(inputDevices.at(0));
+        }
+    }
     struct {
         std::string name;
         NumberSetting* setting;
@@ -210,7 +216,9 @@ void audio::initialize(
             ::input_device = backend->openInputDevice(
                 settings.inputDevice.get(), 44100, 1, 16
             );
-            ::input_device->startCapture();
+            if (::input_device != nullptr) {
+                ::input_device->startCapture();
+            }
         } else {
             if (::input_device) {
                 ::input_device->stopCapture();

src/coders/vector_fonts.cpp

@@ -30,6 +30,7 @@ namespace {
     public:
         FTFontFile(FT_Face face, util::Buffer<ubyte> buffer)
             : face(std::move(face)), buffer(std::move(buffer)) {
+            monospace = this->face->face_flags & FT_FACE_FLAG_FIXED_WIDTH;
         }
 
         ~FTFontFile() {

src/coders/vector_fonts.hpp

@@ -19,6 +19,12 @@ namespace vector_fonts {
         virtual std::unique_ptr<Texture> renderPage(
             int pageid, std::vector<Glyph>& glyphs, int size
         ) = 0;
+
+        bool isMonospace() const {
+            return monospace;
+        }
+    protected:
+        bool monospace = true;
     };
 
     void initialize();

src/devtools/AppScriptsControl.cpp

@@ -0,0 +1,63 @@
+#include "AppScriptsControl.hpp"
+
+#include "debug/Logger.hpp"
+#include "engine/CoreParameters.hpp"
+#include "io/io.hpp"
+#include "Project.hpp"
+#include "logic/scripting/scripting.hpp"
+
+static debug::Logger logger("app-scripts");
+
+AppScriptsControl::AppScriptsControl(
+    const CoreParameters& params, const Project& project
+)
+    : project(project) {
+
+    io::path scriptFile =
+        params.scriptFile.empty()
+            ? "project:start.lua"
+            : std::string("script:") + params.scriptFile.filename().u8string();
+    if (io::exists(scriptFile)) {
+        logger.info() << "starting script: " << params.scriptFile.u8string();
+        scriptCoroutine = scripting::start_app_script(scriptFile);
+    } else {
+        logger.warning() << "script does not exists: " << params.scriptFile.u8string();
+    }
+
+    if (!params.headless) {
+        loadProjectClientScript();
+    }
+}
+
+void AppScriptsControl::loadProjectClientScript() {
+    io::path scriptFile = "project:project_client.lua";
+    if (io::exists(scriptFile)) {
+        logger.info() << "starting project client script: " << scriptFile.string();
+        clientScript = scripting::load_client_project_script(scriptFile);
+    } else {
+        logger.warning() << "project client script does not exists: " << scriptFile.string();
+    }
+}
+
+void AppScriptsControl::onScreenChange(const std::string& name, bool show) {
+    if (clientScript) {
+        clientScript->onScreenChange(name, show);
+    }
+}
+
+void AppScriptsControl::tick() {
+    if (scriptCoroutine && scriptCoroutine->isActive()) {
+        scriptCoroutine->update();
+    }
+}
+
+void AppScriptsControl::terminate(std::string_view reason) {
+    if (scriptCoroutine->isActive()) {
+        scriptCoroutine->terminate();
+        logger.info() << "script has been terminated due to " << reason;
+    }
+}
+
+bool AppScriptsControl::isFinished() const {
+    return scriptCoroutine == nullptr || !scriptCoroutine->isActive();
+}

src/devtools/AppScriptsControl.hpp

@@ -0,0 +1,30 @@
+#pragma once
+
+#include "interfaces/Process.hpp"
+
+#include <memory>
+#include <string>
+
+namespace scripting {
+    class IClientProjectScript;
+}
+
+struct CoreParameters;
+struct Project;
+
+class AppScriptsControl {
+public:
+    AppScriptsControl(const CoreParameters& params, const Project& project);
+
+    void tick();
+    void loadProjectClientScript();
+    void terminate(std::string_view reason);
+
+    void onScreenChange(const std::string& name, bool show);
+
+    bool isFinished() const;
+private:
+    const Project& project;
+    std::unique_ptr<scripting::IClientProjectScript> clientScript;
+    std::unique_ptr<Process> scriptCoroutine;
+};

src/devtools/Project.cpp

@@ -2,6 +2,7 @@
 
 #include "data/dv_util.hpp"
 #include "debug/Logger.hpp"
+#include "engine/CoreParameters.hpp"
 #include "io/io.hpp"
 #include "io/path.hpp"
 #include "logic/scripting/scripting.hpp"
@@ -40,26 +41,6 @@ void Project::deserialize(const dv::value& src) {
     }
 }
 
-void Project::loadProjectClientScript() {
-    io::path scriptFile = "project:project_client.lua";
-    if (io::exists(scriptFile)) {
-        logger.info() << "starting project client script";
-        clientScript = scripting::load_client_project_script(scriptFile);
-    } else {
-        logger.warning() << "project client script does not exists";
-    }
-}
-
-void Project::loadProjectStartScript() {
-    io::path scriptFile = "project:start.lua";
-    if (io::exists(scriptFile)) {
-        logger.info() << "starting project start script";
-        setupCoroutine = scripting::start_app_script(scriptFile);
-    } else {
-        logger.warning() << "project start script does not exists";
-    }
-}
-
 bool Permissions::has(const std::string& name) const {
     return permissions.find(name) != permissions.end();
 }

src/devtools/Project.hpp

@@ -1,17 +1,12 @@
 #pragma once
 
+#include "interfaces/Serializable.hpp"
+
 #include <set>
 #include <string>
 #include <vector>
 #include <memory>
 
-#include "interfaces/Process.hpp"
-#include "interfaces/Serializable.hpp"
-
-namespace scripting {
-    class IClientProjectScript;
-}
-
 struct Permissions {
     static inline std::string DEBUGGING = "debugging";
     static inline std::string NETWORK = "network";
@@ -27,15 +22,10 @@ struct Project : Serializable {
     std::string name;
     std::string title;
     std::vector<std::string> basePacks;
-    std::unique_ptr<scripting::IClientProjectScript> clientScript;
-    std::unique_ptr<Process> setupCoroutine;
     Permissions permissions;
 
     ~Project();
 
     dv::value serialize() const override;
     void deserialize(const dv::value& src) override;
-
-    void loadProjectClientScript();
-    void loadProjectStartScript();
 };

src/engine/Engine.cpp

@@ -13,6 +13,7 @@
 #include "content/ContentControl.hpp"
 #include "core_defs.hpp"
 #include "debug/Logger.hpp"
+#include "devtools/AppScriptsControl.hpp"
 #include "devtools/DebuggingServer.hpp"
 #include "devtools/Editor.hpp"
 #include "devtools/Project.hpp"
@@ -191,10 +192,8 @@ void Engine::initialize(CoreParameters coreParameters) {
         audio::set_input_device(name == "auto" ? "" : name);
     }));
 
-    project->loadProjectStartScript();
-    if (!params.headless) {
-        project->loadProjectClientScript();
-    }
+    appScripts = std::make_unique<AppScriptsControl>(params, *project);
+
     if (params.stdinCommands) {
         cmd::start_stdin_cmd_reader(*this);
     }
@@ -263,9 +262,7 @@ void Engine::detachDebugger() {
 }
 
 void Engine::applicationTick() {
-    if (project->setupCoroutine && project->setupCoroutine->isActive()) {
-        project->setupCoroutine->update();
-    }
+    appScripts->tick();
 }
 
 void Engine::updateFrontend() {
@@ -353,6 +350,7 @@ void Engine::close() {
     network.reset();
     clearKeepedObjects();
     project.reset();
+    appScripts.reset();
     scripting::close();
     logger.info() << "scripting finished";
     if (!params.headless) {
@@ -387,8 +385,8 @@ void Engine::loadProject() {
 }
 
 void Engine::setScreen(std::shared_ptr<Screen> screen) {
-    if (project->clientScript && this->screen) {
-        project->clientScript->onScreenChange(this->screen->getName(), false);
+    if (this->screen) {
+        appScripts->onScreenChange(this->screen->getName(), false);
     }
     // reset audio channels (stop all sources)
     audio::reset_channel(audio::get_channel_index("regular"));
@@ -397,8 +395,8 @@ void Engine::setScreen(std::shared_ptr<Screen> screen) {
     if (this->screen) {
         this->screen->onOpen();
     }
-    if (project->clientScript && this->screen) {
-        project->clientScript->onScreenChange(this->screen->getName(), true);
+    if (this->screen) {
+        appScripts->onScreenChange(this->screen->getName(), true);
         window->setShouldRefresh();
     }
 }

src/engine/Engine.hpp

@@ -12,6 +12,7 @@
 class Assets;
 class AssetsLoader;
 class AssetsManagement;
+class AppScriptsControl;
 class ContentControl;
 class EngineController;
 class EnginePaths;
@@ -55,6 +56,7 @@ class Engine : public util::ObjectsKeeper {
     std::unique_ptr<Project> project;
     std::unique_ptr<SettingsHandler> settingsHandler;
     std::unique_ptr<AssetsManagement> assets;
+    std::unique_ptr<AppScriptsControl> appScripts;
     std::shared_ptr<Screen> screen;
     std::unique_ptr<ContentControl> content;
     std::unique_ptr<EngineController> controller;
@@ -184,5 +186,9 @@ public:
         return debuggingServer.get();
     }
 
+    AppScriptsControl& getAppScripts() {
+        return *appScripts;
+    }
+
     void detachDebugger();
 };

src/engine/Mainloop.cpp

@@ -1,14 +1,17 @@
 #include "Mainloop.hpp"
 
-#include "Engine.hpp"
 #include "debug/Logger.hpp"
+#include "devtools/AppScriptsControl.hpp"
 #include "devtools/Project.hpp"
-#include "frontend/screens/MenuScreen.hpp"
+#include "Engine.hpp"
 #include "frontend/screens/LevelScreen.hpp"
+#include "frontend/screens/MenuScreen.hpp"
+#include "graphics/ui/elements/Container.hpp"
+#include "graphics/ui/GUI.hpp"
+#include "io/path.hpp"
+#include "logic/scripting/scripting.hpp"
 #include "window/Window.hpp"
 #include "world/Level.hpp"
-#include "graphics/ui/GUI.hpp"
-#include "graphics/ui/elements/Container.hpp"
 
 static debug::Logger logger("mainloop");
 
@@ -19,6 +22,7 @@ void Mainloop::run() {
     auto& time = engine.getTime();
     auto& window = engine.getWindow();
     auto& settings = engine.getSettings();
+    const auto& coreParams = engine.getCoreParameters();
 
     engine.setLevelConsumer([this](auto level, int64_t localPlayer) {
         if (level == nullptr) {
@@ -35,9 +39,11 @@ void Mainloop::run() {
 
     logger.info() << "starting menu screen";
     engine.setScreen(std::make_shared<MenuScreen>(engine));
+
+    auto& appScripts = engine.getAppScripts();
     
     logger.info() << "main loop started";
-    while (!window.isShouldClose()){
+    while (!window.isShouldClose()) {
         time.update(window.time());
         engine.applicationTick();
         engine.updateFrontend();
@@ -50,6 +56,10 @@ void Mainloop::run() {
             settings.display.adaptiveFpsInMenu.get() &&
             dynamic_cast<const MenuScreen*>(engine.getScreen().get()) != nullptr
         );
+        if (coreParams.testMode && appScripts.isFinished()) {
+            logger.info() << "test finished";
+            engine.quit();
+        }
     }
     logger.info() << "main loop stopped";
 }

src/engine/ServerMainloop.cpp

@@ -1,13 +1,14 @@
 #include "ServerMainloop.hpp"
 
 #include "Engine.hpp"
-#include "logic/scripting/scripting.hpp"
+#include "devtools/AppScriptsControl.hpp"
 #include "logic/LevelController.hpp"
 #include "interfaces/Process.hpp"
 #include "debug/Logger.hpp"
 #include "world/Level.hpp"
 #include "world/World.hpp"
 #include "util/platform.hpp"
+#include "devtools/Project.hpp"
 
 #include <chrono>
 
@@ -32,21 +33,12 @@ void ServerMainloop::run() {
         setLevel(std::move(level));
     });
 
-    auto process = scripting::start_app_script(
-        "script:" + coreParams.scriptFile.filename().u8string()
-    );
-
     double targetDelta = 1.0 / static_cast<double>(coreParams.tps);
     double delta = targetDelta;
     auto begin = system_clock::now();
     auto startupTime = begin;
 
-    while (process->isActive()) {
-        if (engine.isQuitSignal()) {
-            process->terminate();
-            logger.info() << "script has been terminated due to quit signal";
-            break;
-        }
+    while (!engine.isQuitSignal() && !engine.getAppScripts().isFinished()) {
         if (coreParams.testMode) {
             time.step(delta);
         } else {
@@ -55,7 +47,6 @@ void ServerMainloop::run() {
                 duration_cast<microseconds>(now - startupTime).count() / 1e6);
             delta = time.getDelta();
         }
-        process->update();
         if (controller) {
             controller->getLevel()->getWorld()->updateTimers(delta);
             controller->update(glm::min(delta, 0.2), false);

src/frontend/UiDocument.cpp

@@ -7,6 +7,9 @@
 #include "graphics/ui/elements/InventoryView.hpp"
 #include "graphics/ui/gui_xml.hpp"
 #include "logic/scripting/scripting.hpp"
+#include "debug/Logger.hpp"
+
+static debug::Logger logger("ui-document");
 
 UiDocument::UiDocument(
     std::string id, 
@@ -17,6 +20,19 @@ UiDocument::UiDocument(
     rebuildIndices();
 }
 
+UiDocument::~UiDocument() {
+    try {
+        scripting::on_ui_destroy(*this);
+    } catch (const std::exception& err) {
+        logger.error() << "an error occurred on calling on_destroy event for document '"
+          << id << "': " << err.what();
+    } catch (...) {
+        logger.error() << "unknown exception caught on calling on_destroy "
+                          "event for document '"
+                       << id << "'";
+    }
+}
+
 void UiDocument::rebuildIndices() {
     map.clear();
     gui::UINode::getIndices(root, map);

src/frontend/UiDocument.hpp

@@ -17,6 +17,7 @@ struct UiDocScript {
     bool onopen : 1;
     bool onprogress : 1;
     bool onclose : 1;
+    bool ondestroy : 1;
 };
 
 using UINodesMap = std::unordered_map<std::string, std::weak_ptr<gui::UINode>>;
@@ -35,6 +36,8 @@ public:
         scriptenv env
     );
 
+    ~UiDocument();
+
     void rebuildIndices();
     void pushIndices(const std::shared_ptr<gui::UINode>& node);
 

src/frontend/hud.cpp

@@ -563,7 +563,7 @@ void Hud::add(const HudElement& element, const dv::value& argsArray) {
             args.emplace_back(static_cast<integer_t>(blockPos[i]));
         }
         scripting::on_ui_open(
-            element.getDocument(), 
+            *element.getDocument(), 
             std::move(args)
         );
     }
@@ -578,7 +578,7 @@ void Hud::onRemove(const HudElement& element) {
         if (invview) {
             inventory = invview->getInventory().get();
         }
-        scripting::on_ui_close(document, inventory);
+        scripting::on_ui_close(*document, inventory);
         if (invview) {
             invview->unbind();
         }

src/frontend/menu.cpp

@@ -86,7 +86,7 @@ UiDocument* menus::show(
     );
     auto document = documentPtr.get();
     engine.getAssets()->store(std::move(documentPtr), fullname);
-    scripting::on_ui_open(document, std::move(args));
+    scripting::on_ui_open(*document, std::move(args));
     menu->addPage(name, document->getRoot());
     menu->setPage(name);
     return document;
@@ -99,13 +99,13 @@ void menus::show_process_panel(
 
     auto menu = engine.getGUI().getMenu();
     menu->reset();
-    auto doc =
+    auto document =
         menus::show(engine, "process", {util::wstr2str_utf8(langs::get(text))});
-    std::dynamic_pointer_cast<Container>(doc->getRoot())
+    std::dynamic_pointer_cast<Container>(document->getRoot())
         ->listenInterval(0.01f, [=]() {
             task->update();
 
             uint tasksDone = task->getWorkDone();
-            scripting::on_ui_progress(doc, tasksDone, initialWork);
+            scripting::on_ui_progress(*document, tasksDone, initialWork);
         });
 }

src/graphics/core/Font.cpp

@@ -26,6 +26,11 @@ Font::Font(
       pages(std::move(pages)),
       glyphs(std::move(glyphs)),
       fontFile(std::move(fontFile)) {
+    if (this->fontFile.has_value()) {
+        if (auto fontPtr = this->fontFile->lock()) {
+            monospace = fontPtr->isMonospace();
+        }
+    }
 }
 
 Font::~Font() = default;
@@ -34,6 +39,10 @@ int Font::getYOffset() const {
     return yoffset;
 }
 
+bool Font::isMonospace() const {
+    return monospace;
+}
+
 int Font::getLineHeight() const {
     return lineHeight;
 }
@@ -53,7 +62,7 @@ bool Font::isPrintableChar(uint codepoint) const {
 
 int FontMetrics::calcWidth(std::wstring_view text, size_t offset, size_t length) const {
     auto font = this->font.has_value() ? this->font->lock() : nullptr;
-    if (font == nullptr) {
+    if (font == nullptr || font->isMonospace()) {
         return std::min(text.length() - offset, length) * _glyphInterval;
     }
     int totalWidth = 0;

src/graphics/core/Font.hpp

@@ -39,6 +39,7 @@ public:
     );
     ~Font();
 
+    bool isMonospace() const;
     int getLineHeight() const;
     int getYOffset() const;
     
@@ -94,6 +95,7 @@ private:
     int lineHeight;
     int yoffset;
     int glyphInterval;
+    bool monospace = true;
     std::vector<std::unique_ptr<Texture>> pages;
     std::vector<Glyph> glyphs;
     std::optional<std::weak_ptr<vector_fonts::FontFile>> fontFile;

src/graphics/ui/elements/InlineFrame.cpp

@@ -13,7 +13,7 @@ InlineFrame::~InlineFrame() = default;
 void InlineFrame::setSrc(const std::string& src) {
     this->src = src;
     if (document) {
-        scripting::on_ui_close(document.get(), nullptr);
+        scripting::on_ui_close(*document, nullptr);
         document = nullptr;
         root = nullptr;
     }
@@ -31,7 +31,7 @@ void InlineFrame::setDocument(const std::shared_ptr<UiDocument>& document) {
     root->setSize(size);
 
     gui.postRunnable([this]() {
-        scripting::on_ui_open(this->document.get(), {});
+        scripting::on_ui_open(*this->document, {});
     });
 }
 

src/io/memory_istream.hpp

@@ -15,8 +15,33 @@ public:
     memory_streambuf(const memory_streambuf&) = delete;
     memory_streambuf& operator=(const memory_streambuf&) = delete;
 
+    pos_type seekoff(off_type off, std::ios_base::seekdir way,
+                     std::ios_base::openmode mode = std::ios_base::in) override {
+        if (!(mode & std::ios_base::in)) return pos_type(off_type(-1));
+        char* base = eback();
+        char* end = egptr();
+        if (!base || !end) return pos_type(off_type(-1));
+
+        std::ptrdiff_t current = gptr() - base;
+        std::ptrdiff_t newpos;
+        if (way == std::ios_base::beg) newpos = off;
+        else if (way == std::ios_base::cur) newpos = current + off;
+        else if (way == std::ios_base::end) newpos = (end - base) + off;
+        else return pos_type(off_type(-1));
+
+        if (newpos < 0 || base + newpos > end) return pos_type(off_type(-1));
+        setg(base, base + newpos, end);
+        return pos_type(off_type(newpos));
+    }
+
+    pos_type seekpos(pos_type sp, std::ios_base::openmode mode = std::ios_base::in) override {
+        return seekoff(off_type(sp), std::ios_base::beg, mode);
+    }
 protected:
     int_type underflow() override {
+        if (gptr() < egptr()) {
+            return traits_type::to_int_type(*gptr());
+        }
         return traits_type::eof();
     }
 
@@ -36,7 +61,7 @@ private:
 class memory_view_streambuf : public std::streambuf {
 public:
     explicit memory_view_streambuf(const util::Buffer<char>& buffer)
-        : buffer(std::move(buffer)) {
+        : buffer(buffer) {
         char* base = const_cast<char*>(this->buffer.data());
         char* end = base + this->buffer.size();
         setg(base, base, end);
@@ -45,8 +70,33 @@ public:
     memory_view_streambuf(const memory_view_streambuf&) = delete;
     memory_view_streambuf& operator=(const memory_view_streambuf&) = delete;
 
+    pos_type seekoff(off_type off, std::ios_base::seekdir way,
+                     std::ios_base::openmode mode = std::ios_base::in) override {
+        if (!(mode & std::ios_base::in)) return pos_type(off_type(-1));
+        char* base = eback();
+        char* end = egptr();
+        if (!base || !end) return pos_type(off_type(-1));
+
+        std::ptrdiff_t current = gptr() - base;
+        std::ptrdiff_t newpos;
+        if (way == std::ios_base::beg) newpos = off;
+        else if (way == std::ios_base::cur) newpos = current + off;
+        else if (way == std::ios_base::end) newpos = (end - base) + off;
+        else return pos_type(off_type(-1));
+
+        if (newpos < 0 || base + newpos > end) return pos_type(off_type(-1));
+        setg(base, base + newpos, end);
+        return pos_type(off_type(newpos));
+    }
+
+    pos_type seekpos(pos_type sp, std::ios_base::openmode mode = std::ios_base::in) override {
+        return seekoff(off_type(sp), std::ios_base::beg, mode);
+    }
 protected:
     int_type underflow() override {
+        if (gptr() < egptr()) {
+            return traits_type::to_int_type(*gptr());
+        }
         return traits_type::eof();
     }
 

src/logic/scripting/io_descriptors.cpp

@@ -0,0 +1,133 @@
+#include "logic/scripting/io_descriptors.hpp"
+
+#include "debug/Logger.hpp"
+#include "io/io.hpp"
+
+#include <memory>
+#include <string>
+#include <vector>
+#include <optional>
+
+static debug::Logger logger("descriptors-manager");
+
+using namespace scripting;
+
+namespace {
+    struct StreamDescriptor {
+        // TODO: std::iostream?
+        std::unique_ptr<std::istream> in;
+        std::unique_ptr<std::ostream> out;
+    };
+    std::vector<std::optional<StreamDescriptor>> descriptors;
+}
+
+std::istream* io_descriptors::get_input(int id) {
+    if (!is_readable(id)) {
+        return nullptr;
+    }
+    return ::descriptors[id]->in.get();
+}
+
+std::ostream* io_descriptors::get_output(int id) {
+    if (!is_writeable(id)) {
+        return nullptr;
+    }
+    return ::descriptors[id]->out.get();
+}
+
+static StreamDescriptor& require_descriptor(int id) {
+    if (!io_descriptors::has_descriptor(id)) {
+        throw std::runtime_error(
+            "io-descriptor with id " + std::to_string(id) + " does not exists"
+        );
+    }
+    return *::descriptors[id];
+}
+
+std::istream& io_descriptors::require_input(int id) {
+    const auto& descriptor = require_descriptor(id);
+    if (descriptor.in) {
+        return *descriptor.in;
+    }
+    throw std::runtime_error("io-descriptor is not readable");
+}
+
+std::ostream& io_descriptors::require_output(int id) {
+    const auto& descriptor = require_descriptor(id);
+    if (descriptor.out) {
+        return *descriptor.out;
+    }
+    throw std::runtime_error("io-descriptor is not writeable");
+}
+
+void io_descriptors::flush(int id) {
+    if (is_writeable(id)) {
+        ::descriptors[id]->out->flush();
+    }
+}
+
+bool io_descriptors::has_descriptor(int id) {
+    return id >= 0 && id < static_cast<int>(::descriptors.size()) &&
+           ::descriptors[id].has_value();
+}
+
+bool io_descriptors::is_readable(int id) {
+    return has_descriptor(id) && ::descriptors[id]->in != nullptr;
+}
+
+bool io_descriptors::is_writeable(int id) {
+    return id >= 0 && id < static_cast<int>(::descriptors.size())
+        && ::descriptors[id].has_value()
+        && ::descriptors[id]->out != nullptr;
+}
+
+void io_descriptors::close(int id) {
+    if (!has_descriptor(id)) {
+        return;
+    }
+    auto& desc = ::descriptors[id].value();
+    if (desc.out) {
+        desc.out->flush();
+    }
+    desc.in.reset();
+    desc.out.reset();
+    ::descriptors[id] = std::nullopt;
+}
+
+int io_descriptors::open_descriptor(const io::path& path, bool write, bool read) {
+    std::unique_ptr<std::istream> in;
+    std::unique_ptr<std::ostream> out;
+
+    try {
+        if (read) {
+            in = io::read(path);
+        }
+        if (write) {
+            out = io::write(path);
+        }
+    } catch (const std::exception& e) {
+        logger.error() << "failed to open descriptor for " << path.string()
+                        << ": " << e.what();
+        return -1;
+    }
+
+    for (int i = 0; i < static_cast<int>(descriptors.size()); ++i) {
+        if (!descriptors[i].has_value()) {
+            descriptors[i] = StreamDescriptor{ std::move(in), std::move(out) };
+            return i;
+        }
+    }
+
+    ::descriptors.emplace_back(StreamDescriptor{ std::move(in), std::move(out) });
+    return static_cast<int>(::descriptors.size() - 1);
+}
+
+
+void io_descriptors::close_all_descriptors() {
+    for (int i = 0; i < static_cast<int>(::descriptors.size()); ++i) {
+        if (::descriptors[i].has_value()) {
+            close(i);
+        }
+    }
+    ::descriptors.clear();
+}

src/logic/scripting/io_descriptors.hpp

@@ -0,0 +1,26 @@
+#pragma once
+
+#include <istream>
+#include <ostream>
+
+#include "io/fwd.hpp"
+
+namespace scripting::io_descriptors {
+    std::istream* get_input(int id);
+    std::ostream* get_output(int id);
+
+    std::istream& require_input(int id);
+    std::ostream& require_output(int id);
+
+    void flush(int id);
+
+    bool has_descriptor(int id);
+
+    bool is_readable(int id);
+    bool is_writeable(int id);
+
+    void close(int id);
+    int open_descriptor(const io::path& path, bool write, bool read);
+
+    void close_all_descriptors();
+}

src/logic/scripting/lua/libs/api_lua.hpp

@@ -44,6 +44,7 @@ extern const luaL_Reg posteffectslib[]; // gfx.posteffects
 extern const luaL_Reg quatlib[];
 extern const luaL_Reg randomlib[];
 extern const luaL_Reg compressionlib[];
+extern const luaL_Reg testlib[];
 extern const luaL_Reg text3dlib[]; // gfx.text3d
 extern const luaL_Reg timelib[];
 extern const luaL_Reg tomllib[];

src/logic/scripting/lua/libs/libfile.cpp

@@ -10,7 +10,7 @@
 #include "util/stringutil.hpp"
 #include "api_lua.hpp"
 #include "../lua_engine.hpp"
-#include "logic/scripting/descriptors_manager.hpp"
+#include "logic/scripting/io_descriptors.hpp"
 
 namespace fs = std::filesystem;
 using namespace scripting;
@@ -263,13 +263,13 @@ static int l_open_descriptor(lua::State* L) {
     std::vector<char> buffer;
 
     if(wplusMode) {
-        int temp_descriptor = scripting::descriptors_manager::open_descriptor(path, false, true);
+        int temp_descriptor = io_descriptors::open_descriptor(path, false, true);
 
         if (temp_descriptor == -1) {
             throw std::runtime_error("failed to open descriptor for initial reading");
         }
 
-        auto* in_stream = scripting::descriptors_manager::get_input(temp_descriptor);
+        auto* in_stream = io_descriptors::get_input(temp_descriptor);
 
         in_stream->seekg(0, std::ios::end);
         std::streamsize size = in_stream->tellg();
@@ -278,17 +278,17 @@ static int l_open_descriptor(lua::State* L) {
         buffer.resize(size);
         in_stream->read(buffer.data(), size);
 
-        scripting::descriptors_manager::close(temp_descriptor);
+        io_descriptors::close(temp_descriptor);
     }
 
-    int descriptor = scripting::descriptors_manager::open_descriptor(path, write, read);
+    int descriptor = io_descriptors::open_descriptor(path, write, read);
 
     if(descriptor == -1) {
         throw std::runtime_error("failed to open descriptor");
     }
 
     if(wplusMode) {
-        auto* out_stream = scripting::descriptors_manager::get_output(descriptor);
+        auto* out_stream = io_descriptors::get_output(descriptor);
         out_stream->write(buffer.data(), buffer.size());
         out_stream->flush();
     }
@@ -297,51 +297,31 @@ static int l_open_descriptor(lua::State* L) {
 }
 
 static int l_has_descriptor(lua::State* L) {
-    return lua::pushboolean(L, scripting::descriptors_manager::has_descriptor(lua::tointeger(L, 1)));
+    return lua::pushboolean(L, io_descriptors::has_descriptor(lua::tointeger(L, 1)));
 }
 
 static int l_read_descriptor(lua::State* L) {
     int descriptor = lua::tointeger(L, 1);
-
-    if (!scripting::descriptors_manager::has_descriptor(descriptor)) {
-        throw std::runtime_error("unknown descriptor");
-    }
-
-    if (!scripting::descriptors_manager::is_readable(descriptor)) {
-        throw std::runtime_error("descriptor is not readable");
-    }
-
     int maxlen = lua::tointeger(L, 2);
 
-    auto* stream = scripting::descriptors_manager::get_input(descriptor);
+    auto& stream = io_descriptors::require_input(descriptor);
+    if (stream.eof()) {
+        stream.clear();
+    }
 
     util::Buffer<char> buffer(maxlen);
-
-    stream->read(buffer.data(), maxlen);
-
-    std::streamsize read_len = stream->gcount(); 
-
+    stream.read(buffer.data(), maxlen);
+    std::streamsize read_len = stream.gcount(); 
     return lua::create_bytearray(L, buffer.data(), read_len);
 }
 
 static int l_write_descriptor(lua::State* L) {
     int descriptor = lua::tointeger(L, 1);
-
-    if (!scripting::descriptors_manager::has_descriptor(descriptor)) {
-        throw std::runtime_error("unknown descriptor");
-    }
-
-    if (!scripting::descriptors_manager::is_writeable(descriptor)) {
-        throw std::runtime_error("descriptor is not writeable");
-    }
-
     auto data = lua::bytearray_as_string(L, 2);
 
-    auto* stream = scripting::descriptors_manager::get_output(descriptor);
-
-    stream->write(data.data(), static_cast<std::streamsize>(data.size()));
-
-    if (!stream->good()) {
+    auto& stream = io_descriptors::require_output(descriptor);
+    stream.write(data.data(), static_cast<std::streamsize>(data.size()));
+    if (!stream.good()) {
         throw std::runtime_error("failed to write to stream");
     }
     return 0;
@@ -350,12 +330,13 @@ static int l_write_descriptor(lua::State* L) {
 static int l_seek_descriptor(lua::State* L) {
     int descriptor = lua::tointeger(L, 1);
 
-    if (!scripting::descriptors_manager::has_descriptor(descriptor)) {
+    if (!io_descriptors::has_descriptor(descriptor)) {
         throw std::runtime_error("unknown descriptor");
     }
 
-    std::string mode = lua::require_string(L, 2);
+    auto mode = lua::require_string(L, 2);
     std::ios_base::seekdir dir;
+    auto position = lua::tointeger(L, 3);
 
     switch (mode[0]) {
         case 'b':
@@ -371,29 +352,51 @@ static int l_seek_descriptor(lua::State* L) {
             throw std::runtime_error("invalid seek mode");
     }
 
-    auto* stream = scripting::descriptors_manager::get_output(descriptor);
+    if (io_descriptors::is_writeable(descriptor)) {
+        auto& stream = io_descriptors::require_output(descriptor);
+        stream.seekp(position, dir);
+        if (!stream.good()) {
+            throw std::runtime_error("failed to seek stream");
+        }
+    }
+    if (io_descriptors::is_readable(descriptor)) {
+        auto& stream = io_descriptors::require_input(descriptor);
+        stream.seekg(position, dir);
+        if (!stream.good()) {
+            throw std::runtime_error("failed to seek stream");
+        }
+    }
+    return 0;
+}
 
-    stream->seekp(lua::tointeger(L, 3), dir);
+static int l_tell_descriptor(lua::State* L) {
+    int descriptor = lua::tointeger(L, 1);
 
-    if (!stream->good()) {
-        throw std::runtime_error("failed to seek stream");
+    if (!io_descriptors::has_descriptor(descriptor)) {
+        throw std::runtime_error("unknown descriptor");
     }
 
-    return 0;
+    if (io_descriptors::is_writeable(descriptor)) {
+        auto& stream = io_descriptors::require_output(descriptor);
+        return lua::pushinteger(L, stream.tellp());
+    } else  {
+        auto& stream = io_descriptors::require_input(descriptor);
+        return lua::pushinteger(L, stream.tellg());
+    }
 }
 
 static int l_flush_descriptor(lua::State* L) {
     int descriptor = lua::tointeger(L, 1);
 
-    if (!scripting::descriptors_manager::has_descriptor(descriptor)) {
+    if (!io_descriptors::has_descriptor(descriptor)) {
         throw std::runtime_error("unknown descriptor");
     }
 
-    if (!scripting::descriptors_manager::is_writeable(descriptor)) {
+    if (!io_descriptors::is_writeable(descriptor)) {
         throw std::runtime_error("descriptor is not writeable");
     }
 
-    scripting::descriptors_manager::flush(descriptor);
+    io_descriptors::flush(descriptor);
     return 0;
 }
 
@@ -414,16 +417,16 @@ static int l_available_descriptor(lua::State* L) {
 static int l_close_descriptor(lua::State* L) {
     int descriptor = lua::tointeger(L, 1);
 
-    if (!scripting::descriptors_manager::has_descriptor(descriptor)) {
+    if (!io_descriptors::has_descriptor(descriptor)) {
         throw std::runtime_error("unknown descriptor");
     }
 
-    scripting::descriptors_manager::close(descriptor);
+    io_descriptors::close(descriptor);
     return 0;
 }
 
 static int l_close_all_descriptors(lua::State* L) {
-    scripting::descriptors_manager::close_all_descriptors();
+    io_descriptors::close_all_descriptors();
     return 0;
 }
 
@@ -456,6 +459,7 @@ const luaL_Reg filelib[] = {
     {"__read_descriptor", lua::wrap<l_read_descriptor>},
     {"__write_descriptor", lua::wrap<l_write_descriptor>},
     {"__seek_descriptor", lua::wrap<l_seek_descriptor>},
+    {"__tell_descriptor", lua::wrap<l_tell_descriptor>},
     {"__flush_descriptor", lua::wrap<l_flush_descriptor>},
     {"__available_descriptor", lua::wrap<l_available_descriptor>},
     {"__close_descriptor", lua::wrap<l_close_descriptor>},

src/logic/scripting/lua/libs/libgui.cpp

@@ -420,15 +420,19 @@ static int p_get_data(UINode* node, lua::State* L) {
     return 0;
 }
 
-static const std::string& request_node_id(const DocumentNode& docnode) {
-    std::string id = docnode.node->getId();
+static const std::string& request_node_id(UiDocument& document, UINode& node) {
+    const std::string& id = node.getId();
     if (id.empty()) {
-        id = "#" + std::to_string(
-            reinterpret_cast<std::ptrdiff_t>(docnode.node.get()));
+        node.setId( "#" + std::to_string(
+            reinterpret_cast<std::ptrdiff_t>(&node)));
+        document.pushIndices(node.shared_from_this());
+        return node.getId();
     }
-    docnode.node->setId(std::move(id));
-    docnode.document->pushIndices(docnode.node);
-    return docnode.node->getId();
+    return id;
+}
+
+static const std::string& request_node_id(const DocumentNode& docnode) {
+    return request_node_id(*docnode.document, *docnode.node);
 }
 
 /// @brief Push UI-document node object to stack
@@ -443,15 +447,14 @@ static int push_document_node(lua::State* L, const std::string& id) {
 
 static int p_get_parent(UINode* node, lua::State* L) {
     auto parent = node->getParent();
-    if (!parent) {
+    if (parent == nullptr) {
         return 0;
     }
     auto docname = lua::require_string(L, 1);
     auto element = lua::require_string(L, 2);
     auto docnode = get_document_node_impl(L, docname, element);
 
-    const auto& id = request_node_id(docnode);
-
+    const auto& id = request_node_id(*docnode.document, *parent);
     return push_document_node(L, id);
 }
 
@@ -1144,7 +1147,7 @@ static int l_gui_load_document(lua::State* L) {
     auto document = documentPtr.get();
     engine->requireAssets().store(std::move(documentPtr), alias);
 
-    scripting::on_ui_open(document, {args});
+    scripting::on_ui_open(*document, {args});
     return 0;
 }
 

src/logic/scripting/lua/libs/libtest.cpp

@@ -0,0 +1,45 @@
+#include "api_lua.hpp"
+#include "engine/Engine.hpp"
+#include "window/input.hpp"
+
+#include <iostream>
+
+using namespace scripting;
+
+static int l_set_button_pressed(lua::State* L) {
+    int button = lua::touinteger(L, 1);
+    int x = lua::tointeger(L, 2);
+    int y = lua::tointeger(L, 3);
+    bool pressed = lua::toboolean(L, 4);
+    
+    auto& input = engine->getInput();
+    input.simulateCursorPos(x, y);
+    input.simulateClick(button, pressed);
+    return 0;
+}
+
+static int l_set_key_pressed(lua::State* L) {
+    auto key = lua::require_string(L, 1);
+    bool pressed = lua::toboolean(L, 2);
+    
+    auto& input = engine->getInput();
+    input.simulateKey(input_util::keycode_from(key), pressed);
+    return 0;
+}
+
+static int l_enter_text(lua::State* L) {
+    auto string = lua::require_wstring(L, 1);
+    
+    auto& input = engine->getInput();
+    for (auto chr : string) {
+        input.simulateCodepoint(chr);
+    }
+    return 0;
+}
+
+const luaL_Reg testlib[] = {
+    {"set_button_pressed", lua::wrap<l_set_button_pressed>},
+    {"set_key_pressed", lua::wrap<l_set_key_pressed>},
+    {"enter_text", lua::wrap<l_enter_text>},
+    {nullptr, nullptr}
+};

src/logic/scripting/lua/libs/libworld.cpp

@@ -129,6 +129,9 @@ static int l_get_generator(lua::State* L) {
 }
 
 static int l_get_chunk_data(lua::State* L) {
+    if (level == nullptr) {
+        throw std::runtime_error("world is not open");
+    }
     int x = static_cast<int>(lua::tointeger(L, 1));
     int z = static_cast<int>(lua::tointeger(L, 2));
     const auto& chunk = level->chunks->getChunk(x, z);
@@ -175,7 +178,7 @@ static void integrate_chunk_client(Chunk& chunk) {
 
 static int l_set_chunk_data(lua::State* L) {
     if (level == nullptr) {
-        throw std::runtime_error("no open world");
+        throw std::runtime_error("world is not open");
     }
 
     int x = static_cast<int>(lua::tointeger(L, 1));
@@ -201,7 +204,7 @@ static int l_set_chunk_data(lua::State* L) {
 
 static int l_save_chunk_data(lua::State* L) {
     if (level == nullptr) {
-        throw std::runtime_error("no open world");
+        throw std::runtime_error("world is not open");
     }
 
     int x = static_cast<int>(lua::tointeger(L, 1));

src/logic/scripting/lua/lua_engine.cpp

@@ -19,6 +19,7 @@ namespace {
     debug::Logger logger("lua-state");
     lua::State* main_thread = nullptr;
     bool headless_mode = false;
+    bool test_mode = false;
     const std::unordered_map<std::string, std::string>* project_args;
 }
 
@@ -69,12 +70,12 @@ static void create_libs(State* L, StateType stateType) {
     openlib(L, "yaml", yamllib);
 
     openlib(L, "__vc_app", applib);
-    lua::getglobal(L, "__vc_app");
-    lua::setregistry(L, "app");
+    getglobal(L, "__vc_app");
+    setregistry(L, "app");
 
     if (stateType == StateType::SCRIPT) {
-        lua::getregistry(L, "app");
-        lua::setglobal(L, "app");
+        getregistry(L, "app");
+        setglobal(L, "app");
     }
     if (stateType == StateType::BASE || stateType == StateType::SCRIPT) {
         openlib(L, "assets", assetslib);
@@ -99,6 +100,10 @@ static void create_libs(State* L, StateType stateType) {
         openlib(L, "__transform", transformlib);
     }
 
+    if (::test_mode) {
+        openlib(L, "test", testlib);
+    }
+
     addfunc(L, "print", lua::wrap<l_print>);
     addfunc(L, "crc32", lua::wrap<l_crc32>);
 }
@@ -191,6 +196,7 @@ void lua::initialize(const EnginePaths& paths, const CoreParameters& params) {
     logger.info() << LUAJIT_VERSION;
 
     headless_mode = params.headless;
+    test_mode = params.testMode;
     project_args = &params.projectArgs;
     main_thread = create_state(
         paths, params.headless ? StateType::SCRIPT : StateType::BASE

src/logic/scripting/scripting.cpp

@@ -591,36 +591,46 @@ bool scripting::on_item_break_block(
     );
 }
 
-void scripting::on_ui_open(
-    UiDocument* layout, std::vector<dv::value> args
-) {
-    auto argsptr =
-        std::make_shared<std::vector<dv::value>>(std::move(args));
-    std::string name = layout->getId() + ".open";
-    lua::emit_event(lua::get_main_state(), name, [=](auto L) {
-        for (const auto& value : *argsptr) {
-            lua::pushvalue(L, value);
+static void call_layout_event(const UiDocument& layout, const std::vector<dv::value>& args, const std::string& eventName) {
+    auto L = lua::get_main_state();
+    lua::pushenv(L, *layout.getEnvironment());
+    if (lua::getfield(L, eventName)) {
+        for (const auto& arg : args) {
+            lua::pushvalue(L, arg);
         }
-        return argsptr->size();
-    });
+        lua::call_nothrow(L, args.size(), 0);
+    }
+    lua::pop(L);
+}
+
+void scripting::on_ui_open(
+    const UiDocument& layout, std::vector<dv::value> args
+) {
+    if (layout.getScript().onopen) {
+        call_layout_event(layout, args, "on_open");
+    }
 }
 
 void scripting::on_ui_progress(
-    UiDocument* layout, int workDone, int workTotal
+    const UiDocument& layout, int workDone, int workTotal
 ) {
-    std::string name = layout->getId() + ".progress";
-    lua::emit_event(lua::get_main_state(), name, [=](auto L) {
-        lua::pushinteger(L, workDone);
-        lua::pushinteger(L, workTotal);
-        return 2;
-    });
+    if (layout.getScript().onprogress){
+        call_layout_event(layout, {workDone, workTotal}, "on_progress");
+    }
 }
 
-void scripting::on_ui_close(UiDocument* layout, Inventory* inventory) {
-    std::string name = layout->getId() + ".close";
-    lua::emit_event(lua::get_main_state(), name, [inventory](auto L) {
-        return lua::pushinteger(L, inventory ? inventory->getId() : 0);
-    });
+void scripting::on_ui_close(const UiDocument& layout, Inventory* inventory) {
+    if (layout.getScript().onclose) {
+        call_layout_event(
+            layout, {inventory ? inventory->getId() : 0}, "on_close"
+        );
+    }
+}
+
+void scripting::on_ui_destroy(const UiDocument& layout) {
+    if (layout.getScript().ondestroy) {
+        call_layout_event(layout, {}, "on_destroy");
+    }
 }
 
 void scripting::on_scripts_loading() {
@@ -805,11 +815,14 @@ void scripting::load_layout_script(
 ) {
     int env = *senv;
 
-    lua::pop(lua::get_main_state(), load_script(env, "layout", file, fileName));
-    script.onopen = register_event(env, "on_open", prefix + ".open");
-    script.onprogress =
-        register_event(env, "on_progress", prefix + ".progress");
-    script.onclose = register_event(env, "on_close", prefix + ".close");
+    auto L = lua::get_main_state();
+    lua::pop(L, load_script(env, "layout", file, fileName));
+    lua::pushenv(L, env);
+    script.onopen = lua::hasfield(L, "on_open");
+    script.onprogress = lua::hasfield(L, "on_progress");
+    script.onclose = lua::hasfield(L, "on_close");
+    script.ondestroy = lua::hasfield(L, "on_destroy");
+    lua::pop(L);
 }
 
 void scripting::close() {

src/logic/scripting/scripting.hpp

@@ -152,13 +152,16 @@ namespace scripting {
     void on_attacked(const Entity& entity, Player* player, entityid_t attacker);
     void on_entity_used(const Entity& entity, Player* player);
 
-    /// @brief Called on UI view show
-    void on_ui_open(UiDocument* layout, std::vector<dv::value> args);
+    /// @brief Called on UI document show
+    void on_ui_open(const UiDocument& layout, std::vector<dv::value> args);
 
-    void on_ui_progress(UiDocument* layout, int workDone, int totalWork);
+    void on_ui_progress(const UiDocument& layout, int workDone, int totalWork);
 
-    /// @brief Called on UI view close
-    void on_ui_close(UiDocument* layout, Inventory* inventory);
+    /// @brief Called on UI document close
+    void on_ui_close(const UiDocument& layout, Inventory* inventory);
+
+    /// @brief Called on UI document destroy
+    void on_ui_destroy(const UiDocument& layout);
 
     /// @brief Called on Content loading
     void on_scripts_loading();

src/window/detail/GLFWWindow.cpp

@@ -165,17 +165,127 @@ inline constexpr short MOUSE_KEYS_OFFSET = 1024;
 
 static GLFWcursor* standard_cursors[static_cast<int>(CursorShape::LAST) + 1] = {};
 
-class GLFWInput : public Input {
+class BaseInput : public Input {
 public:
+    std::vector<uint> codepoints;
     int scroll = 0;
+
+    void onKeyCallback(int key, bool pressed) {
+        bool prevPressed = keys[key];
+        keys[key] = pressed;
+        frames[key] = currentFrame;
+        if (pressed && !prevPressed) {
+            const auto& callbacks = keyCallbacks.find(static_cast<Keycode>(key));
+            if (callbacks != keyCallbacks.end()) {
+                callbacks->second.notify();
+            }
+        }
+        if (pressed && key < MOUSE_KEYS_OFFSET) {
+            pressedKeys.push_back(static_cast<Keycode>(key));
+        }
+    }
+
+    void onMouseCallback(int button, bool pressed) {
+        int key = button + MOUSE_KEYS_OFFSET;
+        onKeyCallback(key, pressed);
+    }
+
+    bool isCursorLocked() const override {
+        return cursorLocked;
+    }
+
+    void setCursorPosition(double xpos, double ypos) {
+        if (cursorDrag) {
+            delta.x += xpos - cursor.x;
+            delta.y += ypos - cursor.y;
+        } else {
+            cursorDrag = true;
+        }
+        cursor.x = xpos;
+        cursor.y = ypos;
+    }
+
+    Bindings& getBindings() override {
+        return bindings;
+    }
+
+    const Bindings& getBindings() const override {
+        return bindings;
+    }
+
+    ObserverHandler addKeyCallback(Keycode key, KeyCallback callback) override {
+        return keyCallbacks[key].add(std::move(callback));
+    }
+
+    const std::vector<Keycode>& getPressedKeys() const override {
+        return pressedKeys;
+    }
+
+    const std::vector<uint>& getCodepoints() const override {
+        return codepoints;
+    }
+
+    CursorState getCursor() const override {
+        return {isCursorLocked(), cursor, delta};
+    }
+
+    int getScroll() override {
+        return scroll;
+    }
+
+    bool pressed(Keycode key) const override {
+        int keycode = static_cast<int>(key);
+        if (keycode < 0 || keycode >= KEYS_BUFFER_SIZE) {
+            return false;
+        }
+        return keys[keycode];
+    }
+    bool jpressed(Keycode keycode) const override {
+        return pressed(keycode) &&
+               frames[static_cast<int>(keycode)] == currentFrame;
+    }
+
+    bool clicked(Mousecode code) const override {
+        return pressed(
+            static_cast<Keycode>(MOUSE_KEYS_OFFSET + static_cast<int>(code))
+        );
+    }
+    bool jclicked(Mousecode code) const override {
+        return clicked(code) &&
+               frames[static_cast<int>(code) + MOUSE_KEYS_OFFSET] ==
+                   currentFrame;
+    }
+
+    void simulateKey(Keycode key, bool pressed) override {
+        onKeyCallback(static_cast<int>(key), pressed);
+    }
+
+    void simulateClick(int button, bool pressed) override {
+        onMouseCallback(static_cast<int>(button), pressed);
+    }
+
+    void simulateCursorPos(double xpos, double ypos) override {
+        setCursorPosition(xpos, ypos);
+    }
+    
+    void simulateCodepoint(uint codepoint) override {
+        codepoints.push_back(codepoint);
+    }
+protected:
     uint currentFrame = 0;
     uint frames[KEYS_BUFFER_SIZE] {};
-    std::vector<uint> codepoints;
     std::vector<Keycode> pressedKeys;
     Bindings bindings;
     bool keys[KEYS_BUFFER_SIZE] {};
     std::unordered_map<Keycode, util::HandlersList<>> keyCallbacks;
+    bool cursorLocked = false;
+    bool cursorDrag = false;
+    glm::vec2 delta {};
+    glm::vec2 cursor {};
+};
 
+class GLFWInput : public BaseInput {
+public:
     GLFWInput(GLFWwindow* window)
         : window(window) {
     }
@@ -225,26 +335,6 @@ public:
         }
     }
 
-    void onKeyCallback(int key, bool pressed) {
-        bool prevPressed = keys[key];
-        keys[key] = pressed;
-        frames[key] = currentFrame;
-        if (pressed && !prevPressed) {
-            const auto& callbacks = keyCallbacks.find(static_cast<Keycode>(key));
-            if (callbacks != keyCallbacks.end()) {
-                callbacks->second.notify();
-            }
-        }
-        if (pressed && key < MOUSE_KEYS_OFFSET) {
-            pressedKeys.push_back(static_cast<Keycode>(key));
-        }
-    }
-
-    void onMouseCallback(int button, bool pressed) {
-        int key = button + MOUSE_KEYS_OFFSET;
-        onKeyCallback(key, pressed);
-    }
-
     const char* getClipboardText() const override {
         return glfwGetClipboardString(window);
     }
@@ -253,41 +343,6 @@ public:
         glfwSetClipboardString(window, text);
     }
 
-    int getScroll() override {
-        return scroll;
-    }
-
-    bool pressed(Keycode key) const override {
-        int keycode = static_cast<int>(key);
-        if (keycode < 0 || keycode >= KEYS_BUFFER_SIZE) {
-            return false;
-        }
-        return keys[keycode];
-    }
-    bool jpressed(Keycode keycode) const override {
-        return pressed(keycode) &&
-               frames[static_cast<int>(keycode)] == currentFrame;
-    }
-
-    bool clicked(Mousecode code) const override {
-        return pressed(
-            static_cast<Keycode>(MOUSE_KEYS_OFFSET + static_cast<int>(code))
-        );
-    }
-    bool jclicked(Mousecode code) const override {
-        return clicked(code) &&
-               frames[static_cast<int>(code) + MOUSE_KEYS_OFFSET] ==
-                   currentFrame;
-    }
-
-    CursorState getCursor() const override {
-        return {isCursorLocked(), cursor, delta};
-    }
-
-    bool isCursorLocked() const override {
-        return cursorLocked;
-    }
-
     void toggleCursor() override {
         cursorDrag = false;
         if (cursorLocked) {
@@ -298,43 +353,8 @@ public:
         }
         cursorLocked = !cursorLocked;
     }
-
-    void setCursorPosition(double xpos, double ypos) {
-        if (cursorDrag) {
-            delta.x += xpos - cursor.x;
-            delta.y += ypos - cursor.y;
-        } else {
-            cursorDrag = true;
-        }
-        cursor.x = xpos;
-        cursor.y = ypos;
-    }
-
-    Bindings& getBindings() override {
-        return bindings;
-    }
-
-    const Bindings& getBindings() const override {
-        return bindings;
-    }
-
-    ObserverHandler addKeyCallback(Keycode key, KeyCallback callback) override {
-        return keyCallbacks[key].add(std::move(callback));
-    }
-
-    const std::vector<Keycode>& getPressedKeys() const override {
-        return pressedKeys;
-    }
-
-    const std::vector<uint>& getCodepoints() const override {
-        return codepoints;
-    }
 private:
     GLFWwindow* window;
-    bool cursorLocked = false;
-    bool cursorDrag = false;
-    glm::vec2 delta {};
-    glm::vec2 cursor {};
 };
 static_assert(!std::is_abstract<GLFWInput>());
 

src/window/input.hpp

@@ -274,6 +274,11 @@ public:
     virtual bool clicked(Mousecode mousecode) const = 0;
     virtual bool jclicked(Mousecode mousecode) const = 0;
 
+    virtual void simulateKey(Keycode key, bool pressed) = 0;
+    virtual void simulateClick(int button, bool pressed) = 0;
+    virtual void simulateCursorPos(double xpos, double ypos) = 0;
+    virtual void simulateCodepoint(uint codepoint) = 0;
+
     virtual CursorState getCursor() const = 0;
 
     virtual bool isCursorLocked() const = 0;

test/io/memory_istream.cpp

@@ -16,4 +16,15 @@ TEST(io, memory_istream) {
     ASSERT_EQ(text, std::string(data));
     stream.read(text.data(), 1);
     ASSERT_TRUE(stream.eof());
+
+    // seek
+    stream.clear();
+    stream.seekg(0);
+    ASSERT_TRUE(stream.good());
+    stream.read(text.data(), n);
+    ASSERT_EQ(text, std::string(data));
+    stream.seekg(-6, std::ios_base::cur);
+    ASSERT_TRUE(stream.good());
+    stream.read(text.data(), 6);
+    ASSERT_EQ(text.substr(0, 6), "world!");
 }