test(api): migrate screenchar() test in in window API to screen test

This produces actual output in case of regressions.

1 files changed, 74 insertions, 32 deletions

diff --git a/test/functional/api/window_spec.lua b/test/functional/api/window_spec.lua
index 901d24327c..7c65cf9c37 100644
--- a/test/functional/api/window_spec.lua
+++ b/test/functional/api/window_spec.lua
@@ -15,25 +15,6 @@ local command = helpers.command
 local pcall_err = helpers.pcall_err
 local assert_alive = helpers.assert_alive
 
--- check if str is visible at the beginning of some line
-local function is_visible(str)
-    local slen = string.len(str)
-    local nlines = eval("&lines")
-    for i = 1,nlines do
-        local iseq = true
-        for j = 1,slen do
-            if string.byte(str,j) ~= eval("screenchar("..i..","..j..")") then
-                iseq = false
-                break
-            end
-        end
-        if iseq then
-            return true
-        end
-    end
-    return false
-end
-
 describe('API/win', function()
   before_each(clear)
 
@@ -79,27 +60,61 @@ describe('API/win', function()
     end)
 
     it('updates the screen, and also when the window is unfocused', function()
+      local screen = Screen.new(30, 9)
+      screen:set_default_attr_ids({
+        [1] = {bold = true, foreground = Screen.colors.Blue},
+        [2] = {bold = true, reverse = true};
+        [3] = {reverse = true};
+      })
+      screen:attach()
+
       insert("prologue")
       feed('100o<esc>')
       insert("epilogue")
       local win = curwin()
       feed('gg')
-      poke_eventloop() -- let nvim process the 'gg' command
 
+      screen:expect{grid=[[
+        ^prologue                      |
+                                      |
+                                      |
+                                      |
+                                      |
+                                      |
+                                      |
+                                      |
+                                      |
+      ]]}
       -- cursor position is at beginning
       eq({1, 0}, window('get_cursor', win))
-      eq(true, is_visible("prologue"))
-      eq(false, is_visible("epilogue"))
 
       -- move cursor to end
       window('set_cursor', win, {101, 0})
-      eq(false, is_visible("prologue"))
-      eq(true, is_visible("epilogue"))
+      screen:expect{grid=[[
+                                      |
+                                      |
+                                      |
+                                      |
+                                      |
+                                      |
+                                      |
+        ^epilogue                      |
+                                      |
+      ]]}
 
       -- move cursor to the beginning again
       window('set_cursor', win, {1, 0})
-      eq(true, is_visible("prologue"))
-      eq(false, is_visible("epilogue"))
+      screen:expect{grid=[[
+        ^prologue                      |
+                                      |
+                                      |
+                                      |
+                                      |
+                                      |
+                                      |
+                                      |
+                                      |
+      ]]}
 
       -- move focus to new window
       nvim('command',"new")
@@ -107,18 +122,45 @@ describe('API/win', function()
 
       -- sanity check, cursor position is kept
       eq({1, 0}, window('get_cursor', win))
-      eq(true, is_visible("prologue"))
-      eq(false, is_visible("epilogue"))
+      screen:expect{grid=[[
+        ^                              |
+        {1:~                             }|
+        {1:~                             }|
+        {2:[No Name]                     }|
+        prologue                      |
+                                      |
+                                      |
+        {3:[No Name] [+]                 }|
+                                      |
+      ]]}
 
       -- move cursor to end
       window('set_cursor', win, {101, 0})
-      eq(false, is_visible("prologue"))
-      eq(true, is_visible("epilogue"))
+      screen:expect{grid=[[
+        ^                              |
+        {1:~                             }|
+        {1:~                             }|
+        {2:[No Name]                     }|
+                                      |
+                                      |
+        epilogue                      |
+        {3:[No Name] [+]                 }|
+                                      |
+      ]]}
 
       -- move cursor to the beginning again
       window('set_cursor', win, {1, 0})
-      eq(true, is_visible("prologue"))
-      eq(false, is_visible("epilogue"))
+      screen:expect{grid=[[
+        ^                              |
+        {1:~                             }|
+        {1:~                             }|
+        {2:[No Name]                     }|
+        prologue                      |
+                                      |
+                                      |
+        {3:[No Name] [+]                 }|
+                                      |
+      ]]}
 
       -- curwin didn't change back
       neq(win, curwin())