如何从pytest注入pygame事件？

Question

如何从pytest测试模块向正在运行的pyplay注入事件？

下面是pygame的一个最小示例，它在按下J时绘制一个白色矩形，并在按下Ctrl-Q时退出游戏。

#!/usr/bin/env python
"""minimal_pygame.py"""

import pygame


def minimal_pygame(testing: bool=False):
    pygame.init()
    game_window_sf = pygame.display.set_mode(
            size=(400, 300), 
        )
    pygame.display.flip()
    game_running = True
    while game_running:
        # Main game loop:
        # the following hook to inject events from pytest does not work:
        # if testing:
            # test_input = (yield)
            # pygame.event.post(test_input)
        for event in pygame.event.get():
            # React to closing the pygame window:
            if event.type == pygame.QUIT:
                game_running = False
                break
            # React to keypresses:
            if event.type == pygame.KEYDOWN:
                if event.key == pygame.K_q:
                    # distinguish between Q and Ctrl-Q
                    mods = pygame.key.get_mods()
                    # End main loop if Ctrl-Q was pressed
                    if mods & pygame.KMOD_CTRL:
                        game_running = False
                        break
                # Draw a white square when key J is pressed:
                if event.key == pygame.K_j:
                    filled_rect = game_window_sf.fill(pygame.Color("white"), pygame.Rect(50, 50, 50, 50))
                    pygame.display.update([filled_rect])
    pygame.quit()


if __name__ == "__main__":
    minimal_pygame()

我想写一个pytest模块来自动测试它。我读到过，一个人可以在运行pyplay时注入事件。在这里，我读到从产生允许双向通信，所以我想我必须实现某种钩子，用于从pytest模块注入的pygame.events，但它并不简单正如我所想，所以我评论了它。如果我在下取消注释测试钩子，而game_running，pyplay甚至不等待任何输入。

下面是pytest的测试模块：

#!/usr/bin/env python
"""test_minimal_pygame.py"""

import pygame
import minimal_pygame


def pygame_wrapper(coro):
    yield from coro


def test_minimal_pygame():
    wrap = pygame_wrapper(minimal_pygame.minimal_pygame(testing=True))
    wrap.send(None) # prime the coroutine
    test_press_j = pygame.event.Event(pygame.KEYDOWN, {"key": pygame.K_j})
    for e in [test_press_j]:
        wrap.send(e)

Answer 1

PyGame可以响应自定义用户事件，而不是按键或鼠标事件。下面是一个工作代码，其中pytest向pyplay发送一个用户请求，pyplay对此做出反应，并将响应发送回pytest进行评估：

#!/usr/bin/env python
"""minimal_pygame.py"""

import pygame


TESTEVENT = pygame.event.custom_type()


def minimal_pygame(testing: bool=False):
    pygame.init()
    game_window_sf = pygame.display.set_mode(
            size=(400, 300), 
        )
    pygame.display.flip()
    game_running = True
    while game_running:
        # Hook for testing
        if testing:
            attr_dict = (yield)
            test_event = pygame.event.Event(TESTEVENT, attr_dict)
            pygame.event.post(test_event)
        # Main game loop:
        pygame.time.wait(1000)
        for event in pygame.event.get():
            # React to closing the pygame window:
            if event.type == pygame.QUIT:
                game_running = False
                break
            # React to keypresses:
            if event.type == pygame.KEYDOWN:
                if event.key == pygame.K_q:
                    # distinguish between Q and Ctrl-Q
                    mods = pygame.key.get_mods()
                    # End main loop if Ctrl-Q was pressed
                    if mods & pygame.KMOD_CTRL:
                        game_running = False
                        break
            # React to TESTEVENTS:
            if event.type == TESTEVENT:
                if event.instruction == "draw_rectangle":
                    filled_rect = game_window_sf.fill(pygame.Color("white"), pygame.Rect(50, 50, 50, 50))
                    pygame.display.update([filled_rect])
                    pygame.time.wait(1000)
                    if testing:
                        # Yield the color value of the pixel at (50, 50) back to pytest
                        yield game_window_sf.get_at((50, 50))
    pygame.quit()


if __name__ == "__main__":
    minimal_pygame()

以下是测试代码：

#!/usr/bin/env python
"""test_minimal_pygame.py"""

import minimal_pygame
import pygame


def pygame_wrapper(coro):
    yield from coro


def test_minimal_pygame():
    wrap = pygame_wrapper(minimal_pygame.minimal_pygame(testing=True))
    wrap.send(None) # prime the coroutine
    # Create a dictionary of attributes for the future TESTEVENT
    attr_dict = {"instruction": "draw_rectangle"}
    response = wrap.send(attr_dict)
    assert response == pygame.Color("white")

但是，pytest作为无状态单元测试而不是集成测试的工具，使得pyplay在得到第一个响应（拆卸测试）后退出。这是不可能继续和做更多的测试和断言在当前pyplay会话。（只要尝试复制测试代码的最后两行来重新发送事件，就会失败。）pytest不是一个合适的工具，它可以向pyplay注入一系列指令，使其达到一个先决条件，然后执行一系列测试。

这至少是我从pyplay不和谐频道的人那里听到的。对于自动化集成测试，他们建议使用像Cucumber（或python行为）这样的BDD工具。