#1520 - Add an :ALEDocumentation for tsserver

test/test_hover.vader

@@ -149,3 +149,23 @@ Execute(LSP hover response with lists of strings and marked strings should be ha
 
   AssertEqual ["foo\nbar\n"], g:echo_list
   AssertEqual {}, ale#hover#GetMap()
+
+Execute(tsserver responses for documentation requests should be handled):
+  call ale#hover#SetMap({3: {'show_documentation': 1}})
+
+  call ale#hover#HandleTSServerResponse(
+  \ 1,
+  \ {
+  \   'command': 'quickinfo',
+  \   'request_seq': 3,
+  \   'success': v:true,
+  \   'body': {
+  \     'documentation': 'foo is a very good method',
+  \     'displayString': 'foo bar',
+  \   },
+  \ }
+  \)
+
+  " The preview window should show the text.
+  AssertEqual ['foo is a very good method'], ale#test#GetPreviewWindowText()
+  silent! pclose