Core(Tests): new test for DisallowShadowing

That makes sure that there is no false positive when different
non-nested functions have the same parameter name.

Author: webwarrior-ws

tests/FSharpLint.Core.Tests/Rules/Conventions/DisallowShadowing.fs

@@ -138,6 +138,17 @@ let foo = 1"""
 
         Assert.IsTrue this.NoErrorsExist
 
+    [<Test>]
+    member this.``Should not produce error when parameter with same name exists in another function``() =
+        this.Parse """
+let foo target =
+    target
+
+let bar target =
+    target + 1"""
+
+        Assert.IsTrue this.NoErrorsExist
+
     [<Test>]
     member this.``Should not produce error when variable name starts with underscore``() =
         this.Parse """