Add regression test for 3041. (#3045)

Author: nojaf

CHANGELOG.md

@@ -4,6 +4,7 @@
 
 ### Fixed
 * Equals sign should only be on same line if last tuple is multiline. [#3040](https://github.com/fsprojects/fantomas/issues/3040)
+* Return type should go on next line. [#3041](https://github.com/fsprojects/fantomas/issues/3041)
 
 ## 6.3.0-alpha-007 - 2024-01-27
 

src/Fantomas.Core.Tests/TypeDeclarationTests.fs

@@ -3615,3 +3615,31 @@ type R =
           F2: int
       F3: int }
 """
+
+[<Test>]
+let ``long tupled member where tuple fits on single line but return type doesn't, 3041`` () =
+    formatSourceString
+        """
+type FSharpChecker with
+
+    member this.ParseAndCheckDocument
+        (
+            filePath: string,
+            sourceText: string,
+            options: FSharpProjectOptions,
+            allowStaleResults: bool
+        ) : Async<(FSharpParseFileResults * ParsedInput * FSharpCheckFileResults) option> =
+        ()
+"""
+        config
+    |> prepend newline
+    |> should
+        equal
+        """
+type FSharpChecker with
+
+    member this.ParseAndCheckDocument
+        (filePath: string, sourceText: string, options: FSharpProjectOptions, allowStaleResults: bool)
+        : Async<(FSharpParseFileResults * ParsedInput * FSharpCheckFileResults) option> =
+        ()
+"""