about summary refs log tree commit diff stats
path: root/app.lua
blob: 994f0c7fcd0c0720562aa4ec111c415291cc8169 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
-- love.run: main entrypoint function for LÖVE
--
-- Most apps can just use the default, but we need to override it to
-- install a test harness.
--
-- A test harness needs to check what the 'real' code did.
-- To do this it needs to hook into primitive operations performed by code.
-- Our hooks all go through the `App` global. When running tests they operate
-- on fake screen, keyboard and so on. Once all tests pass, the App global
-- will hook into the real screen, keyboard and so on.
--
-- Scroll below this function for more details.
function love.run()
  App.snapshot_love()
  -- Tests always run at the start.
  App.run_tests_and_initialize()
--?   print('==')

  love.timer.step()
  local dt = 0

  return function()
    if love.event then
      love.event.pump()
      for name, a,b,c,d,e,f in love.event.poll() do
        if name == "quit" then
          if not love.quit or not love.quit() then
            return a or 0
          end
        end
        love.handlers[name](a,b,c,d,e,f)
      end
    end

    -- draw before update to give it a chance to mutate state
    love.graphics.origin()
    love.graphics.clear(love.graphics.getBackgroundColor())
    App.draw()
    love.graphics.present()

    dt = love.timer.step()
    App.update(dt)
    love.timer.sleep(0.001)
  end
end

-- I've been building LÖVE apps for a couple of months now, and often feel
-- stupid. I seem to have a smaller short-term memory than most people, and
-- LÖVE apps quickly grow to a point where I need longer and longer chunks of
-- focused time to make changes to them. The reason: I don't have a way to
-- write tests yet. So before I can change any piece of an app, I have to
-- bring into my head all the ways it can break. This isn't the case on other
-- platforms, where I can be productive in 5- or 10-minute increments. Because
-- I have tests.
--
-- Most test harnesses punt on testing I/O, and conventional wisdom is to test
-- business logic, not I/O. However, any non-trivial app does non-trivial I/O
-- that benefits from tests. And tests aren't very useful if it isn't obvious
-- after reading them what the intent is. Including the I/O allows us to write
-- tests that mimic how people use our program.
--
-- There's a major open research problem in testing I/O: how to write tests
-- for graphics. Pixel-by-pixel assertions get too verbose, and they're often
-- brittle because you don't care about the precise state of every last pixel.
-- Except when you do. Pixels are usually -- but not always -- the trees
-- rather than the forest.
--
-- I'm not in the business of doing research, so I'm going to shave off a
-- small subset of the problem for myself here: how to write tests about text
-- (ignoring font, color, etc.) on a graphic screen.
--
-- For example, here's how you may write a test of a simple text paginator
-- like `less`:
--   function test_paginator()
--     -- initialize environment
--     App.filesystem['/tmp/foo'] = filename([[
--       >abc
--       >def
--       >ghi
--       >jkl
--     ]])
--     App.args = {'/tmp/foo'}
--     -- define a screen with room for 2 lines of text
--     App.screen.init{
--       width=100
--       height=30
--     }
--     App.font.init{
--       height=15
--     }
--     -- check that screen shows next 2 lines of text after hitting pagedown
--     App.run_after_keychord('pagedown')
--     App.screen.check(0, 'ghi')
--     App.screen.check(15, 'jkl')
--   end
--
-- All functions starting with 'test_' (no modules) will run before the app
-- runs "for real". Each such test is a fake run of our entire program. It can
-- set as much of the environment as it wants, then run the app. Here we've
-- got a 30px screen and a 15px font, so the screen has room for 2 lines. The
-- file we're viewing has 4 lines. We assert that hitting the 'pagedown' key
-- shows the third and fourth lines.
--
-- Programs can still perform graphics, and all graphics will work in the real
-- program. We can't yet write tests for graphics, though. Those pixels are
-- basically always blank in tests. Really, there isn't even any
-- representation for them. All our fake screens know about is lines of text,
-- and what (x,y) coordinates they start at. There's some rudimentary support
-- for concatenating all blobs of text that start at the same 'y' coordinate,
-- but beware: text at y=100 is separate and non-overlapping with text at
-- y=101. You have to use the test harness within these limitations for your
-- tests to faithfully model the real world.
--
-- One drawback of this approach: the y coordinate used depends on font size,
-- which feels brittle.
--
-- In the fullness of time App will support all side-effecting primitives
-- exposed by LÖVE, but so far it supports just a rudimentary set of things I
-- happen to have needed so far.

App = {screen={}}

-- save/restore various framework globals we care about -- only on very first load
function App.snapshot_love()
  if Love_snapshot then return end
  Love_snapshot = {}
  -- save the entire initial font; it doesn't seem reliably recreated using newFont
  Love_snapshot.initial_font = love.graphics.getFont()
end

function App.undo_initialize()
  love.graphics.setFont(Love_snapshot.initial_font)
end

function App.run_tests_and_initialize()
  App.load()
  App.run_tests()
  App.disable_tests()
  App.initialize_globals()
  App.initialize(love.arg.parseGameArguments(arg), arg)
end

function App.initialize_for_test()
  App.screen.init({width=100, height=50})
  App.screen.contents = {}  -- clear screen
  App.filesystem = {}
  App.fake_key_pressed = {}
  App.fake_mouse_state = {x=-1, y=-1}
  if App.initialize_globals then App.initialize_globals() end
end

function App.screen.init(dims)
  App.screen.width = dims.width
  App.screen.height = dims.height
end

-- operations on the LÖVE window within the monitor/display
function App.screen.resize(width, height, flags)
  App.screen.width = width
  App.screen.height = height
  App.screen.flags = flags
end

function App.screen.size()
  return App.screen.width, App.screen.height, App.screen.flags
end

function App.screen.move(x,y, displayindex)
  App.screen.x = x
  App.screen.y = y
  App.screen.displayindex = displayindex
end

function App.screen.position()
  return App.screen.x, App.screen.y, App.screen.displayindex
end

function App.screen.print(msg, x,y)
  local screen_row = 'y'..tostring(y)
--?   print('drawing "'..msg..'" at y '..tostring(y))
  local screen = App.screen
  if screen.contents[screen_row] == nil then
    screen.contents[screen_row] = {}
    for i=0,screen.width-1 do
      screen.contents[screen_row][i] = ''
    end
  end
  if x < screen.width then
    screen.contents[screen_row][x] = msg
  end
end

function App.color(color)
  love.graphics.setColor(color.r, color.g, color.b, color.a)
end

App.time = 1
function App.getTime()
  return App.time
end
function App.wait_fake_time(t)
  App.time = App.time + t
end

-- LÖVE's Text primitive retains no trace of the string it was created from,
-- so we'll wrap it for our tests.
--
-- This implies that we need to hook any operations we need on Text objects.
function App.newText(font, s)
  return {type='text', data=s, text=love.graphics.newText(font, s)}
end

function App.width(text)
  return text.text:getWidth()
end

function App.screen.draw(obj, x,y)
  if type(obj) == 'userdata' then
    -- ignore most things as graphics the test harness can't handle
  elseif obj.type == 'text' then
    App.screen.print(obj.data, x,y)
  else
    print(obj.type)
    assert(false)
  end
end

App.clipboard = ''
function App.getClipboardText()
  return App.clipboard
end
function App.setClipboardText(s)
  App.clipboard = s
end

App.fake_key_pressed = {}
function App.fake_key_press(key)
  App.fake_key_pressed[key] = true
end
function App.fake_key_release(key)
  App.fake_key_pressed[key] = nil
end
function App.modifier_down(key)
  return App.fake_key_pressed[key]
end

App.fake_mouse_state = {x=-1, y=-1}  -- x,y always set
function App.fake_mouse_press(x,y, mouse_button)
  App.fake_mouse_state.x = x
  App.fake_mouse_state.y = y
  App.fake_mouse_state[mouse_button] = true
end
function App.fake_mouse_release(x,y, mouse_button)
  App.fake_mouse_state.x = x
  App.fake_mouse_state.y = y
  App.fake_mouse_state[mouse_button] = nil
end
function App.mouse_move(x,y)
  App.fake_mouse_state.x = x
  App.fake_mouse_state.y = y
end
function App.mouse_down(mouse_button)
  return App.fake_mouse_state[mouse_button]
end
function App.mouse_x()
  return App.fake_mouse_state.x
end
function App.mouse_y()
  return App.fake_mouse_state.y
end

-- all textinput events are also keypresses
-- TODO: handle chords of multiple keys
function App.run_after_textinput(t)
  App.keypressed(t)
  App.textinput(t)
  App.keyreleased(t)
  App.screen.contents = {}
  App.draw()
end

-- not all keys are textinput
-- TODO: handle chords of multiple keys
function App.run_after_keychord(chord)
  App.keychord_pressed(chord)
  App.keyreleased(chord)
  App.screen.contents = {}
  App.draw()
end

function App.run_after_mouse_click(x,y, mouse_button)
  App.fake_mouse_press(x,y, mouse_button)
  App.mousepressed(x,y, mouse_button)
  App.fake_mouse_release(x,y, mouse_button)
  App.mousereleased(x,y, mouse_button)
  App.screen.contents = {}
  App.draw()
end

function App.run_after_mouse_press(x,y, mouse_button)
  App.fake_mouse_press(x,y, mouse_button)
  App.mousepressed(x,y, mouse_button)
  App.screen.contents = {}
  App.draw()
end

function App.run_after_mouse_release(x,y, mouse_button)
  App.fake_mouse_release(x,y, mouse_button)
  App.mousereleased(x,y, mouse_button)
  App.screen.contents = {}
  App.draw()
end

function App.screen.check(y, expected_contents, msg)
--?   print('checking for "'..expected_contents..'" at y '..tostring(y))
  local screen_row = 'y'..tostring(y)
  local contents = ''
  if App.screen.contents[screen_row] == nil then
    error('no text at y '..tostring(y))
  end
  for i,s in ipairs(App.screen.contents[screen_row]) do
    contents = contents..s
  end
  check_eq(contents, expected_contents, msg)
end

-- fake files
function App.open_for_writing(filename)
  App.filesystem[filename] = ''
  return {
    write = function(self, ...)
              local args = {...}
              for i,s in ipairs(args) do
                App.filesystem[filename] = App.filesystem[filename]..s
              end
            end,
    close = function(self)
            end,
  }
end

function App.open_for_reading(filename)
  if App.filesystem[filename] then
    return {
      lines = function(self)
                return App.filesystem[filename]:gmatch('[^\n]+')
              end,
      close = function(self)
              end,
    }
  end
end

function App.run_tests()
  local sorted_names = {}
  for name,binding in pairs(_G) do
    if name:find('test_') == 1 then
      table.insert(sorted_names, name)
    end
  end
  table.sort(sorted_names)
  for _,name in ipairs(sorted_names) do
    App.initialize_for_test()
    _G[name]()
  end
  print()
  -- clean up all test methods
  for _,name in ipairs(sorted_names) do
    _G[name] = nil
  end
end

-- call this once all tests are run
-- can't run any tests after this
function App.disable_tests()
  -- have LÖVE delegate all handlers to App if they exist
  for name in pairs(love.handlers) do
    if App[name] then
      love.handlers[name] = App[name]
    end
  end

  -- test methods are disallowed outside tests
  App.run_tests = nil
  App.disable_tests = nil
  App.screen.init = nil
  App.filesystem = nil
  App.time = nil
  App.run_after_textinput = nil
  App.run_after_keychord = nil
  App.keypress = nil
  App.keyrelease = nil
  App.run_after_mouse_click = nil
  App.run_after_mouse_press = nil
  App.run_after_mouse_release = nil
  App.fake_key_pressed = nil
  App.fake_key_press = nil
  App.fake_key_release = nil
  App.fake_mouse_state = nil
  App.fake_mouse_press = nil
  App.fake_mouse_release = nil
  -- other methods dispatch to real hardware
  App.screen.resize = love.window.setMode
  App.screen.size = love.window.getMode
  App.screen.move = love.window.setPosition
  App.screen.position = love.window.getPosition
  App.screen.print = love.graphics.print
  App.newText = love.graphics.newText
  App.screen.draw = love.graphics.draw
  App.width = function(text) return text:getWidth() end
  if Current_app == nil or Current_app == 'run' then
    App.open_for_reading = function(filename) return io.open(filename, 'r') end
    App.open_for_writing = function(filename) return io.open(filename, 'w') end
  elseif Current_app == 'source' then
    -- HACK: source editor requires a couple of different foundational definitions
    App.open_for_reading =
        function(filename)
          local result = love.filesystem.newFile(filename)
          local ok, err = result:open('r')
          if ok then
            return result
          else
            return ok, err
          end
        end
    App.open_for_writing =
        function(filename)
          local result = love.filesystem.newFile(filename)
          local ok, err = result:open('w')
          if ok then
            return result
          else
            return ok, err
          end
        end
  end
  App.getTime = love.timer.getTime
  App.getClipboardText = love.system.getClipboardText
  App.setClipboardText = love.system.setClipboardText
  App.modifier_down = love.keyboard.isDown
  App.mouse_move = love.mouse.setPosition
  App.mouse_down = love.mouse.isDown
  App.mouse_x = love.mouse.getX
  App.mouse_y = love.mouse.getY
end