Fixes 1951 - Single block comment in namespace is disappearing (fspro…

…jects#2089)

* Fixes 1951 (block comment in namespace) by lowering requirements for the node in findNodeBeforeLineAndColumn()

* Explain what's needed to close issues, that aren't reproducable anymore.

* Fixes 1951 (block comment in namespace) by lowering requirements for the node in findNodeBeforeLineAndColumn()

* - Switch fix to use findNodeBeforeLineFromStart() as a fallback if findNodeBeforeLineAndColumn() comes up with None
- Leave findNodeBeforeLineAndColumn() unchanged

* - call findNodeBeforeLineFromStart() only if findNodeAfterLineAndColumn() and findNodeBeforeLineAndColumn() returned None
- fix case of test

src/Fantomas.Tests/CommentTests.fs

@@ -936,6 +936,27 @@ type substring =
 #endif
 """
 
+[<Test>]
+let ``single block comment in namespace, 1951`` () =
+    formatSourceString
+        false
+        """
+namespace ASTViewer.Server
+(* open Microsoft.Azure.Functions.Worker.Http
+open Microsoft.Azure.Functions.Worker
+open Microsoft.Extensions.Logging *)
+"""
+        config
+    |> prepend newline
+    |> should
+        equal
+        """
+namespace ASTViewer.Server
+(* open Microsoft.Azure.Functions.Worker.Http
+open Microsoft.Azure.Functions.Worker
+open Microsoft.Extensions.Logging *)
+"""
+
 [<Test>]
 let ``line comment after "then"`` () =
     formatSourceString

src/Fantomas/Trivia.fs

@@ -279,7 +279,9 @@ let private addTriviaToTriviaNode (startOfSourceCode: int) (triviaNodes: TriviaN
         | Some n, _ ->
             Some n
             |> updateTriviaNode (fun tn -> tn.ContentAfter.Add(Comment(BlockComment(comment, true, false)))) triviaNodes
-        | None, None -> triviaNodes
+        | None, None ->
+            findNodeBeforeLineFromStart triviaNodes range.StartLine
+            |> updateTriviaNode (fun tn -> tn.ContentAfter.Add(Comment(BlockComment(comment, true, true)))) triviaNodes
 
     | { Item = Comment (LineCommentAfterSourceCode _ as comment)
         Range = range } ->