fix(edit): backspace adds extra spaces for inline virtual text (#28005)

Problem:  Backspace adds extra spaces for inline virtual text.
Solution: Ignore virtual text and wrapping when backspacing.

1 files changed, 143 insertions, 0 deletions

diff --git a/test/functional/editor/mode_insert_spec.lua b/test/functional/editor/mode_insert_spec.lua
index e96813b6f7..ebf118736f 100644
--- a/test/functional/editor/mode_insert_spec.lua
+++ b/test/functional/editor/mode_insert_spec.lua
@@ -8,6 +8,7 @@ local command = helpers.command
 local eq = helpers.eq
 local eval = helpers.eval
 local curbuf_contents = helpers.curbuf_contents
+local api = helpers.api
 
 describe('insert-mode', function()
   before_each(function()
@@ -221,4 +222,146 @@ describe('insert-mode', function()
     ]],
     }
   end)
+
+  describe('backspace', function()
+    local function set_lines(line_b, line_e, ...)
+      api.nvim_buf_set_lines(0, line_b, line_e, true, { ... })
+    end
+    local function s(count)
+      return (' '):rep(count)
+    end
+
+    local function test_cols(expected_cols)
+      local cols = { { helpers.fn.col('.'), helpers.fn.virtcol('.') } }
+      for _ = 2, #expected_cols do
+        feed('<BS>')
+        table.insert(cols, { helpers.fn.col('.'), helpers.fn.virtcol('.') })
+      end
+      eq(expected_cols, cols)
+    end
+
+    it('works with tabs and spaces', function()
+      local screen = Screen.new(30, 2)
+      screen:attach()
+      command('setl ts=4 sw=4')
+      set_lines(0, 1, '\t' .. s(4) .. '\t' .. s(9) .. '\t a')
+      feed('$i')
+      test_cols({
+        { 18, 26 },
+        { 17, 25 },
+        { 15, 21 },
+        { 11, 17 },
+        { 7, 13 },
+        { 6, 9 },
+        { 2, 5 },
+        { 1, 1 },
+      })
+    end)
+
+    it('works with varsofttabstop', function()
+      local screen = Screen.new(30, 2)
+      screen:attach()
+      command('setl vsts=6,2,5,3')
+      set_lines(0, 1, 'a\t' .. s(4) .. '\t a')
+      feed('$i')
+      test_cols({
+        { 9, 18 },
+        { 8, 17 },
+        { 8, 14 },
+        { 3, 9 },
+        { 7, 7 },
+        { 2, 2 },
+        { 1, 1 },
+      })
+    end)
+
+    it('works with tab as ^I', function()
+      local screen = Screen.new(30, 2)
+      screen:attach()
+      command('set list listchars=space:.')
+      command('setl ts=4 sw=4')
+      set_lines(0, 1, '\t' .. s(4) .. '\t' .. s(9) .. '\t a')
+      feed('$i')
+      test_cols({
+        { 18, 21 },
+        { 15, 17 },
+        { 11, 13 },
+        { 7, 9 },
+        { 4, 5 },
+        { 1, 1 },
+      })
+    end)
+
+    it('works in replace mode', function()
+      local screen = Screen.new(50, 2)
+      screen:attach()
+      command('setl ts=8 sw=8 sts=8')
+      set_lines(0, 1, '\t' .. s(4) .. '\t' .. s(9) .. '\t a')
+      feed('$R')
+      test_cols({
+        { 18, 34 },
+        { 17, 33 },
+        { 15, 25 },
+        { 7, 17 },
+        { 2, 9 },
+        { 1, 8 }, -- last screen cell of first tab is at vcol 8
+      })
+    end)
+
+    it('works with breakindent', function()
+      local screen = Screen.new(17, 4)
+      screen:attach()
+      command('setl ts=4 sw=4 bri briopt=min:5')
+      set_lines(0, 1, '\t' .. s(4) .. '\t' .. s(9) .. '\t a')
+      feed('$i')
+      test_cols({
+        { 18, 50 },
+        { 17, 49 },
+        { 15, 33 },
+        { 11, 17 },
+        { 7, 13 },
+        { 6, 9 },
+        { 2, 5 },
+        { 1, 1 },
+      })
+    end)
+
+    it('works with inline virtual text', function()
+      local screen = Screen.new(50, 2)
+      screen:attach()
+      command('setl ts=4 sw=4')
+      set_lines(0, 1, '\t' .. s(4) .. '\t' .. s(9) .. '\t a')
+      local ns = api.nvim_create_namespace('')
+      local vt_opts = { virt_text = { { 'text' } }, virt_text_pos = 'inline' }
+      api.nvim_buf_set_extmark(0, ns, 0, 2, vt_opts)
+      feed('$i')
+      test_cols({
+        { 18, 30 },
+        { 17, 29 },
+        { 15, 25 },
+        { 11, 21 },
+        { 7, 17 },
+        { 6, 13 },
+        { 2, 9 },
+        { 1, 5 },
+      })
+    end)
+
+    it("works with 'revins'", function()
+      local screen = Screen.new(30, 3)
+      screen:attach()
+      command('setl ts=4 sw=4 revins')
+      set_lines(0, 1, ('a'):rep(16), s(3) .. '\t' .. s(4) .. '\t a')
+      feed('j$i')
+      test_cols({
+        { 11, 14 },
+        { 10, 13 },
+        { 9, 9 },
+        { 5, 5 },
+        { 1, 1 },
+        { 1, 1 }, -- backspace on empty line does nothing
+      })
+      eq(2, api.nvim_win_get_cursor(0)[1])
+    end)
+  end)
 end)