first successful pagedown test, first bug found by test

I also really need to rethink how people debug my programs. My approach
of inserting and deleting print() takes a lot of commitment. I need my
old trace-based whitebox testing idea. However, in my past projects I
never did figure out a good framework for tweaking how verbose a trace
to emit.

Perhaps that's too many knobs. Perhaps we just need a way to run a
single test with the most verbose trace possible. Then it's just a
matter of having the trace tell a coherent story? But even if the trace
stays out of program output in that situation, it's still in the
programmer's face in the _code_. Ugh.

Current plan: ship program with maximum tests and zero commented-out
prints. If you want to debug, insert prints. This is better than
previous, text-mode, projects just by virtue of the stdout channel being
dedicated to debug stuff.

app.lua

@@ -93,7 +93,7 @@ end
 --     App.font{
 --       height=15
 --     }
---     App.run_with_keypress('pagedown')
+--     App.run_after_keypress('pagedown')
 --     App.check_screen_contents{
 --       y0='ghi'
 --       y15=''
@@ -138,6 +138,7 @@ 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] = {}
@@ -175,6 +176,12 @@ function App.run_after_textinput(t)
   App.draw()
 end
 
+function App.run_after_keychord(key)
+  App.keychord_pressed(key)
+  App.screen.contents = {}
+  App.draw()
+end
+
 function App.width(text)
   return text.text:getWidth()
 end
@@ -182,6 +189,9 @@ end
 function App.screen.check(y, expected_contents, msg)
   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

file.lua

@@ -107,13 +107,18 @@ end
 function load_array(a)
   local result = {}
   local next_line = ipairs(a)
-  local i,line = 0, ''
+  local i,line,drawing = 0, ''
   while true do
     i,line = next_line(a, i)
     if i == nil then break end
+--?     print(line)
     if line == '```lines' then  -- inflexible with whitespace since these files are always autogenerated
-      table.insert(result, load_drawing_from_array(next_line, a, i))
+--?       print('inserting drawing')
+      i, drawing = load_drawing_from_array(next_line, a, i)
+--?       print('i now', i)
+      table.insert(result, drawing)
     else
+--?       print('inserting text')
       table.insert(result, {mode='text', data=line})
     end
   end
@@ -129,6 +134,7 @@ function load_drawing_from_array(iter, a, i)
   while true do
     i, line = iter(a, i)
     assert(i)
+--?     print(i)
     if line == '```' then break end
     local shape = json.decode(line)
     if shape.mode == 'freehand' then
@@ -156,5 +162,5 @@ function load_drawing_from_array(iter, a, i)
     end
     table.insert(drawing.shapes, shape)
   end
-  return drawing
+  return i, drawing
 end

main.lua

@@ -81,7 +81,7 @@ Zoom = 1.5
 
 Filename = love.filesystem.getUserDirectory()..'/lines.txt'
 
-New_foo = true
+Debug_main = false
 
   if #arg > 0 then
     Filename = arg[1]
@@ -120,9 +120,9 @@ function App.draw()
     line.y = nil
   end
   local y = 15
-  if New_foo then print('== draw') end
+  if Debug_main then print('== draw') end
   for line_index,line in ipairs(Lines) do
-    if New_foo then print('draw:', line_index, y) end
+    if Debug_main then print('draw:', line_index, y) end
     if y + math.floor(15*Zoom) > App.screen.height then break end
     if line_index >= Screen_top1.line then
       Screen_bottom1.line = line_index
@@ -146,15 +146,15 @@ function App.draw()
         Drawing.draw(line)
         y = y + Drawing.pixels(line.h) + 10 -- padding
       else
-        if New_foo then print('text') end
+        if Debug_main then print('text') end
         line.y = y
         y, Screen_bottom1.pos = Text.draw(line, Line_width, line_index)
         y = y + math.floor(15*Zoom)  -- text height
-        if New_foo then print('aa', y) end
+        if Debug_main then print('aa', y) end
       end
     end
   end
-  New_foo = false
+  Debug_main = false
 --?   print('screen bottom: '..tostring(Screen_bottom1.pos)..' in '..tostring(Lines[Screen_bottom1.line].data))
 --?   os.exit(1)
 end
@@ -195,7 +195,7 @@ function App.textinput(t)
 end
 
 function App.keychord_pressed(chord)
-  New_foo = true
+--?   Debug_main = true
   if love.mouse.isDown('1') or chord:sub(1,2) == 'C-' then
     Drawing.keychord_pressed(chord)
   elseif chord == 'escape' and love.mouse.isDown('1') then
@@ -226,6 +226,7 @@ function App.keychord_pressed(chord)
     end
     save_to_disk(Lines, Filename)
   elseif chord == 'pagedown' then
+    print('setting top to', Screen_bottom1.line)
     Screen_top1.line = Screen_bottom1.line
     Screen_top1.pos = Screen_bottom1.pos
     Cursor1.line = Screen_top1.line

text.lua

@@ -28,7 +28,7 @@ function Text.draw(line, line_width, line_index)
       assert(x > 25)  -- no overfull lines
       if line_index > Screen_top1.line or pos > Screen_top1.pos then
         y = y + math.floor(15*Zoom)
-        if New_foo then print('text: new screen line', y, Screen_height, screen_line_starting_pos) end
+        if New_foo then print('text: new screen line', y, App.screen.height, screen_line_starting_pos) end
         screen_line_starting_pos = pos
         if Debug_new_render then print('y', y) end
       end
@@ -39,7 +39,7 @@ function Text.draw(line, line_width, line_index)
         table.insert(line.screen_line_starting_pos, pos)
       end
       if line_index > Screen_top1.line or pos > Screen_top1.pos then
-        if y + math.floor(15*Zoom) >= Screen_height then
+        if y + math.floor(15*Zoom) >= App.screen.height then
           return y, screen_line_starting_pos
         end
       end
@@ -79,6 +79,7 @@ function Text.draw_cursor(x, y)
 end
 
 function test_draw_text()
+  print('test_draw_text')
   App.screen.init{width=120, height=60}
   Lines = load_array{'abc', 'def', 'ghi'}
   Line_width = 120
@@ -97,6 +98,59 @@ function test_draw_text()
   App.screen.check(y, 'ghi', 'F - test_draw_text/screen:3')
 end
 
+function test_pagedown()
+  print('test_pagedown')
+  App.screen.init{width=120, height=45}
+  Lines = load_array{'abc', 'def', 'ghi'}
+  Line_width = 120
+  Cursor1 = {line=1, pos=1}
+  Screen_top1 = {line=1, pos=1}
+  Screen_bottom1 = {}
+  Zoom = 1
+  local screen_top_margin = 15  -- pixels
+  local line_height = math.floor(15*Zoom)  -- pixels
+  -- initially the first two lines are displayed
+  App.draw()
+  local y = screen_top_margin
+  App.screen.check(y, 'abc', 'F - test_pagedown/baseline/screen:1')
+  y = y + line_height
+  App.screen.check(y, 'def', 'F - test_pagedown/baseline/screen:2')
+  -- after pagedown the bottom line becomes the top
+  App.run_after_keychord('pagedown')
+  y = screen_top_margin
+  App.screen.check(y, 'def', 'F - test_pagedown/screen:1')
+  y = y + line_height
+  App.screen.check(y, 'ghi', 'F - test_pagedown/screen:2')
+end
+
+function test_pagedown_skip_drawings()
+  print('test_pagedown_skip_drawings')
+  -- some lines of text with a drawing intermixed
+  App.screen.init{width=50, height=45}
+  Lines = load_array{'abc',
+                     '```lines', '```',
+                     'def',
+                     'ghi'}
+  check_eq(Lines[2].mode, 'drawing', 'F - test_pagedown_skip_drawings/baseline/lines')
+  Line_width = App.screen.width
+  Cursor1 = {line=1, pos=1}
+  Screen_top1 = {line=1, pos=1}
+  Screen_bottom1 = {}
+  Zoom = 1
+  local screen_top_margin = 15  -- pixels
+  local drawing_height = App.screen.width / 2  -- default
+  -- initially the screen displays the first line and part of the drawing
+  App.draw()
+  local y = screen_top_margin
+  App.screen.check(y, 'abc', 'F - test_pagedown_skip_drawings/baseline/screen:1')
+  -- after pagedown the screen draws the screen up top
+  App.run_after_keychord('pagedown')
+  y = screen_top_margin + drawing_height
+  App.screen.check(y, 'def', 'F - test_pagedown_skip_drawings/screen:1')
+  y = y + line_height
+  App.screen.check(y, 'ghi', 'F - test_pagedown_skip_drawings/screen:2')
+end
+
 function Text.compute_fragments(line, line_width)
   line.fragments = {}
   local x = 25
@@ -376,6 +430,7 @@ function Text.move_cursor_down_to_next_text_line_while_scrolling_again_if_necess
     table.insert(Lines, {mode='text', data=''})
   end
   if Cursor1.line > Screen_bottom1.line then
+    print('scroll up')
     Screen_top1.line = Cursor1.line
     Text.scroll_up_while_cursor_on_screen()
   end
@@ -384,7 +439,7 @@ end
 function Text.scroll_up_while_cursor_on_screen()
   local top2 = Text.to2(Cursor1)
 --?   print('cursor pos '..tostring(Cursor1.pos)..' is on the #'..tostring(top2.screen_line)..' screen line down')
-  local y = Screen_height - math.floor(15*Zoom)
+  local y = App.screen.height - math.floor(15*Zoom)
   -- duplicate some logic from love.draw
   while true do
 --?     print(y, 'top2:', top2.line, top2.screen_line, top2.screen_pos)