public void StatementNode_WhenToStringCalled_ReturnsCorrectString() { // Arranged: var exprNodeMock = new Mock <IExpressionNode>(); exprNodeMock.Setup(node => node.ToString()).Returns(() => "\"a\""); var stmtNode = new StatementNode(new Token(TokenKind.Identifier, "<S>"), _tracer) { Expression = exprNodeMock.Object }; // Act: var actual = stmtNode.ToString(); // Assert: Assert.That(actual, Is.EqualTo("<S> ::= \"a\" .")); }