I have exception
class SyntaxError : Exception {
public SyntaxError(int l) {
line = l;
}
public int line;
}
我正在使用单元测试来测试类解析器,该解析器在特定输入上应该抛出上面的异常。我正在使用这样的代码:
[TestMethod]
[ExpectedException(typeof(Parser.SyntaxError))]
public void eolSyntaxError()
{
parser.reader = new StringReader("; alfan; betannnna");
parser.eol();
}
有没有聪明的简单方法来检查SyntaxError.line == 1
?
我想出的最好的是:
[TestMethod]
public void eolSyntaxError()
{
try {
parser.reader = new StringReader("; alfan; betannnna");
parser.eol();
Assert.Fail();
} catch (SyntaxError e) {
Assert.AreEqual(1, e.line);
}
}
我不太喜欢它,有更好的方法吗?
考虑使用 FluentAssertions。然后,您的测试将如下所示:
[TestMethod]
public void eolSyntaxError()
{
parser.reader = new StringReader("; alfan; betannnna");
Action parseEol = () => parser.eol();
parseEol
.ShouldThrow<SyntaxError>()
.And.line.Should().Be(1);
}
否则,你的方法几乎和它得到的一样好。
您可以编写类似于 NUnit 中的方法
public T Throws<T>(Action code) where T : Exception
{
Exception coughtException = null;
try
{
code();
}
catch (Exception ex)
{
coughtException = ex;
}
Assert.IsNotNull(coughtException, "Test code didn't throw exception");
Assert.AreEqual(coughtException.GetType(), typeof(T), "Test code didn't throw same type exception");
return (T)coughtException;
}
然后您可以在测试方法中使用它
Parser.SyntaxError exception = Throws<Parser.SyntaxError>(() => parser.eol());
Assert.AreEqual(1, exception.line);
根据我的评论,如果您遇到语法错误的行是相关的,请将其包含在自定义异常类中,如下所示。
public class SyntaxError : Exception
{
public SyntaxError(int atLine)
{
AtLine = atLine;
}
public int AtLine { get; private set; }
}
然后很容易测试。
编辑 - 阅读问题(!)后,这里有一个简单的附加断言方法,它将整理您的异常断言。
public static class xAssert
{
public static TException Throws<TException>(Action a) where TException : Exception
{
try
{
a();
}
catch (Exception ex)
{
var throws = ex as TException;
if (throws != null)
return throws;
}
Assert.Fail();
return default(TException);
}
}
用法如下...
public class Subject
{
public void ThrowMyException(int someState)
{
throw new MyException(someState);
}
public void ThrowSomeOtherException()
{
throw new InvalidOperationException();
}
}
public class MyException : Exception
{
public int SomeState { get; private set; }
public MyException(int someState)
{
SomeState = someState;
}
}
[TestClass]
public class UnitTest1
{
[TestMethod]
public void TestMethod1()
{
var subject = new Subject();
var exceptionThrown = xAssert.Throws<MyException>(() => { subject.ThrowMyException(123); });
Assert.AreEqual(123, exceptionThrown.SomeState);
}
}
有开箱即用的解决方案,但我已经看到了这样的期望概念:
[TestMethod]
public void EolSyntaxError()
{
Expectations.Expect<(SyntaxError>(
() =>
{
parser.reader = new StringReader("; alfan; betannnna");
parser.eol();
},
e =>
{
Assert.AreEqual(1, e.line);
});
}
期望需要实现。我认为会有图书馆已经这样做了。无论如何,Expectations
中的Expect
方法可能如下所示:
public static void Expect<TExpectedException>(
System.Action action,
System.Action<TExpectedException> assertion) where TExpectedException : Exception
{
if (action == null) { throw new ArgumentNullException("action"); }
try
{
action.Invoke();
Assert.Fail(string.Format("{0} expected to be thrown", typeof(TExpectedException).Name));
}
catch (TExpectedException e)
{
assertion.Invoke(e);
}
}