Fix text edit when insert empty new text (#384)

* Add test of 'lsp#utils#text_edit#apply_text_edits'.

* Fix `lsp#utils#text_edit#apply_text_edits` is delete one character when textEdit command kind is insert.

I fix the problem the apply_text_edits is deleting one character
if "textEdit['range']['start'] equals textEdit['range']['end'] and textEdit['new Text'] is empty".

* Fix tests.

- create new buffer each tests
- add test utility function `s:set_text` and `get_text`

Author: mikoto2000

autoload/lsp/utils/text_edit.vim

@@ -157,14 +157,10 @@ function! s:generate_sub_cmd_insert(text_edit) abort
     let l:sub_cmd = s:preprocess_cmd(a:text_edit['range'])
     let l:sub_cmd .= s:generate_move_start_cmd(l:start_line, l:start_character)
 
-    if len(l:new_text) == 0
-        let l:sub_cmd .= 'x'
+    if l:start_character >= len(getline(l:start_line))
+        let l:sub_cmd .= 'a'
     else
-        if l:start_character >= len(getline(l:start_line))
-            let l:sub_cmd .= 'a'
-        else
-            let l:sub_cmd .= 'i'
-        endif
+        let l:sub_cmd .= 'i'
     endif
 
     let l:sub_cmd .= printf('%s', l:new_text)

test/lsp/utils/text_edit.vimspec

@@ -0,0 +1,120 @@
+function! s:set_text(lines)
+    % delete _
+    put =a:lines
+    execute 'normal ggdd'
+endfunction
+
+function! s:get_text()
+    return lsp#utils#buffer#_get_lines(bufnr('$'))
+endfunction
+
+Describe lsp#utils#text_edit
+
+    Before all
+        let s:endofline_backup = &endofline
+        set endofline
+    End
+
+    After all
+        let &endofline = s:endofline_backup
+    End
+
+    Before each
+        enew!
+    End
+
+    Describe lsp#utils#text_edit#apply_text_edits
+        It insert newText
+            call s:set_text(['foo', 'bar'])
+
+            call lsp#utils#text_edit#apply_text_edits(
+                    \ expand('%'),
+                    \ [{
+                    \   'range': {
+                    \       'start': {
+                    \           'line': 1,
+                    \           'character': 1
+                    \       },
+                    \       'end': {
+                    \           'line': 1,
+                    \           'character': 1
+                    \       }
+                    \   },
+                    \   'newText': 'baz'
+                    \ }])
+
+            let l:buffer_text = s:get_text()
+            Assert Equals(l:buffer_text, ['foo', 'bbazar', ''])
+        End
+
+        It insert empty newText
+            call s:set_text(['foo', 'bar'])
+
+            call lsp#utils#text_edit#apply_text_edits(
+                    \ expand('%'),
+                    \ [{
+                    \   'range': {
+                    \       'start': {
+                    \           'line': 1,
+                    \           'character': 1
+                    \       },
+                    \       'end': {
+                    \           'line': 1,
+                    \           'character': 1
+                    \       }
+                    \   },
+                    \   'newText': ''
+                    \ }])
+
+            let l:buffer_text = s:get_text()
+            Assert Equals(l:buffer_text, ['foo', 'bar', ''])
+        End
+
+        It replace range string to newText
+            call s:set_text(['foo', 'bar'])
+
+            call lsp#utils#text_edit#apply_text_edits(
+                    \ expand('%'),
+                    \ [{
+                    \   'range': {
+                    \       'start': {
+                    \           'line': 1,
+                    \           'character': 0
+                    \       },
+                    \       'end': {
+                    \           'line': 1,
+                    \           'character': 1
+                    \       }
+                    \   },
+                    \   'newText': 'replaced'
+                    \ }])
+
+            let l:buffer_text = s:get_text()
+            Assert Equals(l:buffer_text, ['foo', 'replacedar', ''])
+        End
+
+        It delete range string
+            call s:set_text(['foo', 'bar'])
+
+            call lsp#utils#text_edit#apply_text_edits(
+                    \ expand('%'),
+                    \ [{
+                    \   'range': {
+                    \       'start': {
+                    \           'line': 1,
+                    \           'character': 0
+                    \       },
+                    \       'end': {
+                    \           'line': 1,
+                    \           'character': 1
+                    \       }
+                    \   },
+                    \   'newText': ''
+                    \ }])
+
+            let l:buffer_text = s:get_text()
+            Assert Equals(l:buffer_text, ['foo', 'ar', ''])
+        End
+    End
+End
+