Add new tests for RedundantNewKeyword rule

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

@@ -97,3 +97,31 @@ module Program
 
         Assert.IsTrue this.ErrorsExist
 
+    [<Test>]
+    member this.``new keyword is required.``() =
+        this.Parse
+            """
+open System
+
+type ISomeInterfaceWithDisposable =
+    interface
+        inherit IDisposable
+    end
+
+type SomeDisposableType() =
+    interface ISomeInterfaceWithDisposable with
+        member _.Dispose() = ()
+
+module Program =
+    let foo = new SomeDisposableType() :> ISomeInterfaceWithDisposable"""
+
+        this.AssertNoWarnings()
+
+    [<Test>]
+    member this.``New keyword is required for known type that implements IDisposable``() =
+        this.Parse
+            """module Program
+
+let foo = new System.Net.Http.HttpClient()"""
+
+        this.AssertNoWarnings()