Moving UpcastDowncastTests over to NUnit (#7229)

* Moving UpcastDowncastTests over to NUnit

* missing new line

tests/fsharp/Compiler/ErrorMessages/UpcastDowncastTests.fs

@@ -0,0 +1,51 @@
+// Copyright (c) Microsoft Corporation.  All Rights Reserved.  See License.txt in the project root for license information.
+
+namespace FSharp.Compiler.UnitTests
+
+open NUnit.Framework
+open FSharp.Compiler.SourceCodeServices
+
+[<TestFixture>]
+module ``Upcast and Downcast`` =
+
+    [<Test>]
+    let ``Downcast Instead Of Upcast``() =
+        CompilerAssert.TypeCheckSingleError
+            """
+open System.Collections.Generic
+
+let orig = Dictionary<obj,obj>() :> IDictionary<obj,obj>
+let c = orig :> Dictionary<obj,obj>
+            """
+            FSharpErrorSeverity.Error
+            193
+            (5, 9, 5, 36)
+            "Type constraint mismatch. The type \n    'IDictionary<obj,obj>'    \nis not compatible with type\n    'Dictionary<obj,obj>'    \n"
+
+    [<Test>]
+    let ``Upcast Instead Of Downcast``() =
+        CompilerAssert.TypeCheckWithErrors
+            """
+open System.Collections.Generic
+
+let orig = Dictionary<obj,obj>()
+let c = orig :?> IDictionary<obj,obj>
+            """
+            [|
+                FSharpErrorSeverity.Warning, 67, (5, 9, 5, 38), "This type test or downcast will always hold"
+                FSharpErrorSeverity.Error, 3198, (5, 9, 5, 38), "The conversion from Dictionary<obj,obj> to IDictionary<obj,obj> is a compile-time safe upcast, not a downcast. Consider using the :> (upcast) operator instead of the :?> (downcast) operator."
+            |]
+
+    [<Test>]
+    let ``Upcast Function Instead Of Downcast``() =
+        CompilerAssert.TypeCheckWithErrors
+            """
+open System.Collections.Generic
+
+let orig = Dictionary<obj,obj>()
+let c : IDictionary<obj,obj> = downcast orig
+            """
+            [|
+                FSharpErrorSeverity.Warning, 67, (5, 32, 5, 45), "This type test or downcast will always hold"
+                FSharpErrorSeverity.Error, 3198, (5, 32, 5, 45), "The conversion from Dictionary<obj,obj> to IDictionary<obj,obj> is a compile-time safe upcast, not a downcast. Consider using 'upcast' instead of 'downcast'."
+            |]

tests/fsharp/FSharpSuite.Tests.fsproj

@@ -36,6 +36,7 @@
     <Compile Include="Compiler\ErrorMessages\AccessOfTypeAbbreviationTests.fs" />
     <Compile Include="Compiler\ErrorMessages\ElseBranchHasWrongTypeTests.fs" />
     <Compile Include="Compiler\ErrorMessages\MissingElseBranch.fs" />
+    <Compile Include="Compiler\ErrorMessages\UpcastDowncastTests.fs" />
     <Compile Include="Compiler\SourceTextTests.fs" />
     <Compile Include="Compiler\Language\AnonRecordTests.fs" />
     <Compile Include="Compiler\Language\SpanOptimizationTests.fs" />

tests/fsharpqa/Source/Warnings/env.lst

@@ -38,9 +38,6 @@
 	SOURCE=SuggestToUseIndexer.fs # SuggestToUseIndexer.fs
 	SOURCE=RefCellInsteadOfNot.fs # RefCellInsteadOfNot.fs
 	SOURCE=RefCellInsteadOfNot2.fs # RefCellInsteadOfNot2.fs
-	SOURCE=UpcastInsteadOfDowncast.fs # UpcastInsteadOfDowncast.fs
-	SOURCE=UpcastFunctionInsteadOfDowncast.fs # UpcastFunctionInsteadOfDowncast.fs
-	SOURCE=DowncastInsteadOfUpcast.fs # DowncastInsteadOfUpcast.fs
 	SOURCE=RuntimeTypeTestInPattern.fs # RuntimeTypeTestInPattern.fs
 	SOURCE=RuntimeTypeTestInPattern2.fs # RuntimeTypeTestInPattern2.fs
 	SOURCE=WarnIfExpressionResultUnused.fs # WarnIfExpressionResultUnused.fs