Test(FavourIgnoreOverLetWild): add a failure test

Author: Mersho

tests/FSharpLint.Core.Tests/Rules/Binding/FavourIgnoreOverLetWild.fs

@@ -50,3 +50,20 @@ let a = List.iter (fun x -> ()) []
 
         Assert.IsFalse(this.ErrorsExist)
 
+    [<Test>]
+    member this.LetWildcardUnitValueSuggestedFix() =
+        let source = """
+module Program
+
+let _ = ()"""
+        let expected = """
+module Program
+
+(()) |> ignore"""
+        this.Parse source
+
+        Assert.IsTrue(this.ErrorExistsAt(4, 4))
+
+        let result = this.ApplyQuickFix source
+
+        Assert.AreEqual(expected, result)