Added simple base tests for C# and VB

src/Compilers/CSharp/Test/Semantic/IOperation/IOperationTests_IInstanceReferenceTests.cs

+// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
+
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+using Microsoft.CodeAnalysis.Test.Utilities;
+using Xunit;
+
+namespace Microsoft.CodeAnalysis.CSharp.UnitTests
+{
+    public partial class IOperationTests : SemanticModelTestBase
+    {
+        [CompilerTrait(CompilerFeature.IOperation)]
+        [Fact]
+        public void IInstanceReferenceExpression_SimpleBaseReference()
+        {
+            string source = @"
+using System;
+
+public class C1
+{
+    public virtual void M1() { }
+}
+
+public class C2 : C1
+{
+    public override void M1()
+    {
+        /*<bind>*/base/*</bind>*/.M1();
+    }
+}
+";
+            string expectedOperationTree = @"
+IInstanceReferenceExpression (IsBaseReference: True) (OperationKind.InstanceReferenceExpression, Type: C1) (Syntax: 'base')
+";
+            var expectedDiagnostics = DiagnosticDescription.None;
+
+            VerifyOperationTreeAndDiagnosticsForTest<BaseExpressionSyntax>(source, expectedOperationTree, expectedDiagnostics);
+        }
+
+        [CompilerTrait(CompilerFeature.IOperation)]
+        [Fact]
+        public void IInstanceReferenceExpression_BaseNoMemberReference()
+        {
+            string source = @"
+using System;
+
+public class C1
+{
+    public virtual void M1()
+    {
+        /*<bind>*/base/*</bind>*/.M1();
+    }
+}
+";
+            string expectedOperationTree = @"
+IInstanceReferenceExpression (IsBaseReference: True) (OperationKind.InstanceReferenceExpression, Type: System.Object) (Syntax: 'base')
+";
+            var expectedDiagnostics = new DiagnosticDescription[] {
+                // CS0117: 'object' does not contain a definition for 'M1'
+                //         /*<bind>*/base/*</bind>*/.M1();
+                Diagnostic(ErrorCode.ERR_NoSuchMember, "M1").WithArguments("object", "M1").WithLocation(8, 35)
+            };
+
+            VerifyOperationTreeAndDiagnosticsForTest<BaseExpressionSyntax>(source, expectedOperationTree, expectedDiagnostics);
+        }
+
+
+    }
+}

src/Compilers/VisualBasic/Test/Semantic/IOperation/IOperationTests_IInstanceReferenceExpression.vb

+' Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
+
+Imports Microsoft.CodeAnalysis.Test.Utilities
+Imports Microsoft.CodeAnalysis.VisualBasic.Syntax
+
+Namespace Microsoft.CodeAnalysis.VisualBasic.UnitTests.Semantics
+
+    Partial Public Class IOperationTests
+        Inherits SemanticModelTestBase
+
+        <CompilerTrait(CompilerFeature.IOperation)>
+        <Fact()>
+        Public Sub IInstanceReferenceExpression_SimpleBaseReference()
+            Dim source = <![CDATA[
+Option Strict On
+
+Public Class C1
+    Public Overridable Sub M1()
+    End Sub
+End Class
+
+Public Class C2
+    Inherits C1
+    Public Overrides Sub M1()
+        MyBase.M1()'BIND:"MyBase"
+    End Sub
+End Class]]>.Value
+
+            Dim expectedOperationTree = <![CDATA[
+IInstanceReferenceExpression (IsBaseReference: True) (OperationKind.InstanceReferenceExpression, Type: C1) (Syntax: 'MyBase')
+]]>.Value
+
+            Dim expectedDiagnostics = String.Empty
+
+            VerifyOperationTreeAndDiagnosticsForTest(Of MyBaseExpressionSyntax)(source, expectedOperationTree, expectedDiagnostics)
+        End Sub
+
+        <CompilerTrait(CompilerFeature.IOperation)>
+        <Fact()>
+        Public Sub IInstanceReferenceExpression_BaseNoMemberReferene()
+            Dim source = <![CDATA[
+Option Strict On
+
+Public Class C1
+    Public Overridable Sub M1()
+        MyBase.M1()'BIND:"MyBase"
+    End Sub
+End Class]]>.Value
+
+            Dim expectedOperationTree = <![CDATA[
+IInstanceReferenceExpression (IsBaseReference: True) (OperationKind.InstanceReferenceExpression, Type: System.Object, IsInvalid) (Syntax: 'MyBase')
+]]>.Value
+
+            Dim expectedDiagnostics = <![CDATA[
+BC30456: 'M1' is not a member of 'Object'.
+        MyBase.M1()'BIND:"MyBase"
+        ~~~~~~~~~
+]]>.Value
+
+            VerifyOperationTreeAndDiagnosticsForTest(Of MyBaseExpressionSyntax)(source, expectedOperationTree, expectedDiagnostics)
+        End Sub
+
+
+
+    End Class
+End Namespace