Add regression tests for IOperation. (#22837)

Closes #7582.

src/Compilers/CSharp/Test/Semantic/IOperation/IOperationTests_IFieldReferenceExpression.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.
+// 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.CSharp.Test.Utilities;
@@ -160,5 +160,83 @@ public void IFieldReferenceExpression_InferenceDeconstructionDeclaration_Alterna
             VerifyOperationTreeAndDiagnosticsForTest<DeclarationExpressionSyntax>(source, expectedOperationTree, expectedDiagnostics,
                 parseOptions: TestOptions.Script);
         }
+
+        [CompilerTrait(CompilerFeature.IOperation)]
+        [WorkItem(7582, "https://github.com/dotnet/roslyn/issues/7582")]
+        [Fact]
+        public void IFieldReferenceExpression_ImplicitThis ()
+        {
+            string source = @"
+class C
+{
+    int i;
+    void M()
+    {
+        /*<bind>*/i/*</bind>*/ = 1;
+        i++;
+    }
+}
+";
+            string expectedOperationTree = @"
+IFieldReferenceExpression: System.Int32 C.i (OperationKind.FieldReferenceExpression, Type: System.Int32) (Syntax: 'i')
+  Instance Receiver: 
+    IInstanceReferenceExpression (OperationKind.InstanceReferenceExpression, Type: C, IsImplicit) (Syntax: 'i')";
+            var expectedDiagnostics = DiagnosticDescription.None;
+
+            VerifyOperationTreeAndDiagnosticsForTest<IdentifierNameSyntax>(source, expectedOperationTree, expectedDiagnostics);
+        }
+
+        [CompilerTrait(CompilerFeature.IOperation)]
+        [WorkItem(7582, "https://github.com/dotnet/roslyn/issues/7582")]
+        [Fact]
+        public void IFieldReferenceExpression_ExplicitThis()
+        {
+            string source = @"
+class C
+{
+    int i;
+    void M()
+    {
+        /*<bind>*/this.i/*</bind>*/ = 1;
+        i++;
+    }
+}
+";
+            string expectedOperationTree = @"
+IFieldReferenceExpression: System.Int32 C.i (OperationKind.FieldReferenceExpression, Type: System.Int32) (Syntax: 'this.i')
+  Instance Receiver: 
+    IInstanceReferenceExpression (OperationKind.InstanceReferenceExpression, Type: C) (Syntax: 'this')";
+            var expectedDiagnostics = DiagnosticDescription.None;
+
+            VerifyOperationTreeAndDiagnosticsForTest<MemberAccessExpressionSyntax>(source, expectedOperationTree, expectedDiagnostics);
+        }
+
+        [CompilerTrait(CompilerFeature.IOperation)]
+        [WorkItem(7582, "https://github.com/dotnet/roslyn/issues/7582")]
+        [Fact]
+        public void IFieldReferenceExpression_base()
+        {
+            string source = @"
+class C
+{
+    protected int i;
+}
+class B : C
+{
+    void M()
+    {
+        /*<bind>*/base.i/*</bind>*/ = 1;
+        i++;
+    }
+}
+";
+            string expectedOperationTree = @"
+IFieldReferenceExpression: System.Int32 C.i (OperationKind.FieldReferenceExpression, Type: System.Int32) (Syntax: 'base.i')
+  Instance Receiver: 
+    IInstanceReferenceExpression (OperationKind.InstanceReferenceExpression, Type: C) (Syntax: 'base')";
+            var expectedDiagnostics = DiagnosticDescription.None;
+
+            VerifyOperationTreeAndDiagnosticsForTest<MemberAccessExpressionSyntax>(source, expectedOperationTree, expectedDiagnostics);
+        }
     }
 }

src/Compilers/VisualBasic/Test/Semantic/IOperation/IOperationTests_IFieldReferenceExpression.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.
+' 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.Semantics
 Imports Microsoft.CodeAnalysis.Test.Utilities
@@ -36,5 +36,99 @@ IOperation:  (OperationKind.None) (Syntax: 'Conditional(field)')
 
             VerifyOperationTreeAndDiagnosticsForTest(Of AttributeSyntax)(source, expectedOperationTree, expectedDiagnostics)
         End Sub
+
+        <CompilerTrait(CompilerFeature.IOperation)>
+        <Fact, WorkItem(7582, "https://github.com/dotnet/roslyn/issues/7582")>
+        Public Sub FieldReference_ImplicitMe()
+            Dim source = <![CDATA[
+Class C
+    Private i As Integer
+
+    Private Sub M()
+         i = 1 'BIND:"i"
+    End Sub
+End Class]]>.Value
+
+            Dim expectedOperationTree = <![CDATA[
+IFieldReferenceExpression: C.i As System.Int32 (OperationKind.FieldReferenceExpression, Type: System.Int32) (Syntax: 'i')
+  Instance Receiver: 
+    IInstanceReferenceExpression (OperationKind.InstanceReferenceExpression, Type: C, IsImplicit) (Syntax: 'i')
+]]>.Value
+
+            Dim expectedDiagnostics = String.Empty
+
+            VerifyOperationTreeAndDiagnosticsForTest(Of IdentifierNameSyntax)(source, expectedOperationTree, expectedDiagnostics)
+        End Sub
+
+        <CompilerTrait(CompilerFeature.IOperation)>
+        <Fact, WorkItem(7582, "https://github.com/dotnet/roslyn/issues/7582")>
+        Public Sub FieldReference_ExplicitMe()
+            Dim source = <![CDATA[
+Class C
+    Private i As Integer
+
+    Private Sub M()
+         Me.i = 1 'BIND:"Me.i"
+    End Sub
+End Class]]>.Value
+
+            Dim expectedOperationTree = <![CDATA[
+IFieldReferenceExpression: C.i As System.Int32 (OperationKind.FieldReferenceExpression, Type: System.Int32) (Syntax: 'Me.i')
+  Instance Receiver: 
+    IInstanceReferenceExpression (OperationKind.InstanceReferenceExpression, Type: C) (Syntax: 'Me')
+]]>.Value
+
+            Dim expectedDiagnostics = String.Empty
+
+            VerifyOperationTreeAndDiagnosticsForTest(Of MemberAccessExpressionSyntax)(source, expectedOperationTree, expectedDiagnostics)
+        End Sub
+
+        <CompilerTrait(CompilerFeature.IOperation)>
+        <Fact, WorkItem(7582, "https://github.com/dotnet/roslyn/issues/7582")>
+        Public Sub FieldReference_MyBase()
+            Dim source = <![CDATA[
+Class C
+    Protected i As Integer
+End Class
+Class B
+    Inherits C
+    Private Sub M()
+         MyBase.i = 1 'BIND:"MyBase.i"
+    End Sub
+End Class]]>.Value
+
+            Dim expectedOperationTree = <![CDATA[
+IFieldReferenceExpression: C.i As System.Int32 (OperationKind.FieldReferenceExpression, Type: System.Int32) (Syntax: 'MyBase.i')
+  Instance Receiver: 
+    IInstanceReferenceExpression (OperationKind.InstanceReferenceExpression, Type: C) (Syntax: 'MyBase')
+]]>.Value
+
+            Dim expectedDiagnostics = String.Empty
+
+            VerifyOperationTreeAndDiagnosticsForTest(Of MemberAccessExpressionSyntax)(source, expectedOperationTree, expectedDiagnostics)
+        End Sub
+
+        <CompilerTrait(CompilerFeature.IOperation)>
+        <Fact, WorkItem(7582, "https://github.com/dotnet/roslyn/issues/7582")>
+        Public Sub FieldReference_MyClass()
+            Dim source = <![CDATA[
+Class C
+    Private i As Integer
+
+    Private Sub M()
+         MyClass.i = 1 'BIND:"MyClass.i"
+    End Sub
+End Class]]>.Value
+
+            Dim expectedOperationTree = <![CDATA[
+IFieldReferenceExpression: C.i As System.Int32 (OperationKind.FieldReferenceExpression, Type: System.Int32) (Syntax: 'MyClass.i')
+  Instance Receiver: 
+    IInstanceReferenceExpression (OperationKind.InstanceReferenceExpression, Type: C) (Syntax: 'MyClass')
+]]>.Value
+
+            Dim expectedDiagnostics = String.Empty
+
+            VerifyOperationTreeAndDiagnosticsForTest(Of MemberAccessExpressionSyntax)(source, expectedOperationTree, expectedDiagnostics)
+        End Sub
     End Class
 End Namespace