-- 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.

-- but we need to override it to:
--   * run all tests (functions starting with 'test_') on startup, and
--   * save some state that makes it possible to switch between the main app
--     and a source editor, while giving each the illusion of complete
--     control.

-- 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.

-- The rest of this file wraps around various LÖVE primitives to support
-- automated tests. Often tests will run with a fake version of a primitive
-- that redirects to the real love.* version once we're done with tests.

-- 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.

-- Not everything is so wrapped yet. Sometimes you still have to use love.*
-- primitives directly.

App = {screen={}}

App = {}

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()
--?     print('=== '..name)
--?     _G[name]()
    xpcall(_G[name], function(err) prepend_debug_info_to_test_failure(name, err) end)
  end
  -- clean up all test methods
  for _,name in ipairs(sorted_names) do
    _G[name] = nil
  end
end

-- App.screen.resize and App.screen.move seem like better names than
-- love.window.setMode and love.window.setPosition respectively. They'll
-- be side-effect-free during tests, and they'll save their results in
-- attributes of App.screen for easy access.
App.screen={}
-- Use App.screen.init in tests to initialize the fake screen.

-- operations on the LÖVE window within the monitor/display

-- If you use App.screen.print instead of love.graphics.print,
-- tests will be able to check what was printed using App.screen.check below.
--
-- One drawback of this approach: the y coordinate used depends on font size,
-- which feels brittle.

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

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)

function colortable(app_color)
  return {app_color.r, app_color.g, app_color.b, app_color.a}
end

-- If you access the time using App.getTime instead of love.timer.getTime,
-- tests will be able to move the time back and forwards as needed using
-- App.wait_fake_time below.

-- If you access the clipboard using App.getClipboardText and
-- App.setClipboardText instead of love.system.getClipboardText and
-- love.system.setClipboardText respectively, tests will be able to manipulate
-- the clipboard by reading/writing App.clipboard.

-- In tests I mostly send chords all at once to the keyboard handlers.
-- However, you'll occasionally need to check if a key is down outside a handler.
-- If you use App.key_down instead of love.keyboard.isDown, tests will be able to
-- simulate keypresses using App.fake_key_press and App.fake_key_release
-- below. This isn't very realistic, though, and it's up to tests to
-- orchestrate key presses that correspond to the handlers they invoke.

function App.key_down(key)
  return App.fake_keys_pressed[key]
end

end
function App.key_down(key)
  return App.fake_keys_pressed[key]

-- Tests mostly will invoke mouse handlers directly. However, you'll
-- occasionally need to check if a mouse button is down outside a handler.
-- If you use App.mouse_down instead of love.mouse.isDown, tests will be able to
-- simulate mouse clicks using App.fake_mouse_press and App.fake_mouse_release
-- below. This isn't very realistic, though, and it's up to tests to
-- orchestrate presses that correspond to the handlers they invoke.

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

end
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
-- If you use App.open_for_reading and App.open_for_writing instead of other
-- various Lua and LÖVE helpers, tests will be able to check the results of
-- file operations inside the App.filesystem table.
function App.open_for_writing(filename)
  App.filesystem[filename] = ''
  if Current_app == nil or Current_app == 'run' then
    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,
    }
  elseif Current_app == 'source' then
    return {
      write = function(self, s)
                App.filesystem[filename] = App.filesystem[filename]..s
              end,
      close = function(self)
              end,
    }
  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

-- Some helpers to trigger an event and then refresh the screen. Akin to one
-- iteration of the event loop.

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

-- miscellaneous internal helpers

-- fake files
function App.open_for_writing(filename)
  App.filesystem[filename] = ''
  if Current_app == nil or Current_app == 'run' then
    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,
    }
  elseif Current_app == 'source' then
    return {
      write = function(self, s)
                App.filesystem[filename] = App.filesystem[filename]..s
              end,
      close = function(self)
              end,
    }
  end

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

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()
--?     print('=== '..name)
--?     _G[name]()
    xpcall(_G[name], function(err) prepend_debug_info_to_test_failure(name, err) end)
  end
  -- clean up all test methods
  for _,name in ipairs(sorted_names) do
    _G[name] = nil
  end

function colortable(app_color)
  return {app_color.r, app_color.g, app_color.b, app_color.a}