Fix ale#util#GetBufferContents and propagate use (#4457)

* Use newline characters instead in ale#util#GetBufferContents
* Propagate use of ale#util#GetBufferContents
* Add ale#util#GetContentBuffer test

autoload/ale/lsp/message.vim

@@ -52,28 +52,24 @@ function! ale#lsp#message#Exit() abort
 endfunction
 
 function! ale#lsp#message#DidOpen(buffer, language_id) abort
-    let l:lines = getbufline(a:buffer, 1, '$')
-
     return [1, 'textDocument/didOpen', {
     \   'textDocument': {
     \       'uri': ale#util#ToURI(expand('#' . a:buffer . ':p')),
     \       'languageId': a:language_id,
     \       'version': ale#lsp#message#GetNextVersionID(),
-    \       'text': join(l:lines, "\n") . "\n",
+    \       'text': ale#util#GetBufferContents(a:buffer),
     \   },
     \}]
 endfunction
 
 function! ale#lsp#message#DidChange(buffer) abort
-    let l:lines = getbufline(a:buffer, 1, '$')
-
     " For changes, we simply send the full text of the document to the server.
     return [1, 'textDocument/didChange', {
     \   'textDocument': {
     \       'uri': ale#util#ToURI(expand('#' . a:buffer . ':p')),
     \       'version': ale#lsp#message#GetNextVersionID(),
     \   },
-    \   'contentChanges': [{'text': join(l:lines, "\n") . "\n"}]
+    \   'contentChanges': [{'text': ale#util#GetBufferContents(a:buffer)}]
     \}]
 endfunction
 

autoload/ale/util.vim

@@ -542,7 +542,7 @@ function! ale#util#SetBufferContents(buffer, lines) abort
 endfunction
 
 function! ale#util#GetBufferContents(buffer) abort
-    return join(getbufline(a:buffer, 1, '$'), '\n') . '\n'
+    return join(getbufline(a:buffer, 1, '$'), "\n") . "\n"
 endfunction
 
 function! ale#util#ToURI(resource) abort

test/lsp/test_lsp_client_messages.vader

@@ -36,6 +36,9 @@ Given typescript(A TypeScript file with 3 lines):
   bar()
   baz()
 
+Execute(ale#util#GetBufferContents() should return correctly formatted newlines):
+  AssertEqual "foo()\nbar()\nbaz()\n", ale#util#GetBufferContents(bufnr(''))
+
 Execute(ale#lsp#message#DidOpen() should return correct messages):
   let g:ale_lsp_next_version_id = 12
   AssertEqual