public void ParseExpression_UnexpectedSymbol_ThrowsParseExpressionException()
{
// Arrange
var tokens = new Queue <Token>(new[]
{
// 1 $ 2
new Token(new[] { '1' }, 1),
new Token(new[] { '$' }),
new Token(new[] { '2' }, 2),
new Token(new[] { '\0' })
});
var tokenizerMock = new Mock <ITokenizer>();
var operationFactoryMock = new Mock <IOperationFactory>();
var engine = new MathExpressionEngine(operationFactoryMock.Object);
Token token = null;
tokenizerMock.Setup(x => x.Init()).Callback(() => token = tokens.Dequeue());
tokenizerMock.Setup(x => x.NextToken()).Callback(() => token = tokens.Dequeue());
tokenizerMock.SetupGet(x => x.CurrentToken).Returns(() => token);
operationFactoryMock.Setup(x => x.IsSupportedOperation(It.IsAny <char>())).Returns(false);
// Act
Action result = () => engine.ParseExpression(tokenizerMock.Object);
// Assert
result.Should().Throw <ExpressionParseException>().WithMessage("Unexpected symbol: $");
}
private static void Main()
{
while (true)
{
Console.WriteLine("Enter expression:");
var expression = Console.ReadLine();
if (string.IsNullOrEmpty(expression))
{
continue;
}
if (expression.Equals("exit", StringComparison.OrdinalIgnoreCase))
{
break;
}
try
{
using var reader = new StringReader(expression);
var tokenizer = new Tokenizer(reader);
var operationFactory = new OperationFactory();
var engine = new MathExpressionEngine(operationFactory);
var result = engine.ParseExpression(tokenizer).Eval();
Console.WriteLine($"Your result: {result}");
}
catch (ExpressionParseException ex)
{
Console.WriteLine(ex.Message);
}
}
}
public void ParseExpression_ValidExpression_ReturnsParsedResult()
{
// Arrange
var tokens = new Queue <Token>(new[]
{
// -((10 + 20) - 5 * 5 + 2 * 2)
new Token(new[] { '-' }),
new Token(new[] { '(' }),
new Token(new[] { '(' }),
new Token(new[] { '1', '0' }, 10),
new Token(new[] { '+' }),
new Token(new[] { '2', '0' }, 20),
new Token(new[] { ')' }),
new Token(new[] { '-' }),
new Token(new[] { '5' }, 5),
new Token(new[] { '*' }),
new Token(new[] { '5' }, 5),
new Token(new[] { '+' }),
new Token(new[] { '2' }, 2),
new Token(new[] { '*' }),
new Token(new[] { '2' }, 2),
new Token(new[] { ')' }),
new Token(new[] { '\0' })
});
var tokenizerMock = new Mock <ITokenizer>();
var operationFactoryMock = new Mock <IOperationFactory>();
var engine = new MathExpressionEngine(operationFactoryMock.Object);
Token token = null;
tokenizerMock.Setup(x => x.Init()).Callback(() => token = tokens.Dequeue());
tokenizerMock.Setup(x => x.NextToken()).Callback(() => token = tokens.Dequeue());
tokenizerMock.SetupGet(x => x.CurrentToken).Returns(() => token);
operationFactoryMock.Setup(x => x.IsSupportedOperation(It.IsAny <char>())).Returns(true);
operationFactoryMock.Setup(x => x.CreateLowPriorityOperation('+')).Returns((a, b) => a + b);
operationFactoryMock.Setup(x => x.CreateLowPriorityOperation('-')).Returns((a, b) => a - b);
operationFactoryMock.Setup(x => x.CreateHighPriorityOperation('*')).Returns((a, b) => a * b);
// Act
var result = engine.ParseExpression(tokenizerMock.Object).Eval();
// Assert
result.Should().Be(-9);
}
