public void BeginSyntax_WhenGivenAToken_PushesSyntaxNode() { // Arrange: var token = new Token() { TokenKind = TokenKind.String, Image = "a" }; var stack = new Stack <IAstNode>(); var builder = new AstBuilder(_nodeFactoryMock.Object, null, stack, _tracerMock.Object); // Act: builder.BeginSyntax(token); // Assert: Assert.That(stack.Count, Is.EqualTo(1)); Assert.That(stack.Peek(), Is.InstanceOf <ISyntaxNode>()); }