单元测试断言在几种情况下都是正确的

Question

I am trying to write a unit test where I check that a certain result is correct. However, there are two results that would be considered correct. Is there a way to do an OR with assertions? I know that I could do result = x || result = y and assert that this is true. But rather than seeing true != false, I would like to see result != x or y.

The framework I am using is mstest, but I would be open to hearing suggestions for nunit as well.

Answer 1

You could try Fluent Assertions . This is a set of .NET extension methods that allow you to more naturally specify the expected outcome test. Fluent Assertions supports both MSTest and NUnit, so it will be not a big deal to switch later to nUnit. Then you could express your assertion using following snippet:

// Act phase: you get result somehow
var result = 42;

// Assert phase
result.Should().BeOneOf(new [] { 1, 2 } ); 
// in this case you'll be following error:
// Expected value to be one of {1, 41}, but found 42.

Answer 2

There is a nice Constraint-Based Assert Model in NUnit. It allows to define compound constraints. See details here

In your case assert might write:

Assert.That(result, Is.EqualTo(1).Or.EqualTo(5));

The failed test message would be (eg):
Expected: 1 or 5
But was: 10

Answer 3

你可以做：

Assert.IsTrue( result == x || result == y );

Answer 4

The easiest option is to just use Assert.IsTrue , but also pass a string message to print upon failure. That string can give the information about how the reality failed to meet the expectation:

Assert.IsTrue(result == x || result == y, "Result was not x or y");

You can easily include the actual value in your custom message also:

Assert.IsTrue(result == x || result == y, "Result was not x or y, instead it was {0}", result);

Alternatively, you could store your "correct" values in a Collection and then use CollectionAssert.Contains .

Answer 5

You can create your Assert method in case the actual result could match more than two expected values:

public void AssertMultipleValues<T>(object actual, params object[] expectedResults)
{
    Assert.IsInstanceOfType(actual, typeof(T));

    bool isExpectedResult = false;
    foreach (object expectedResult in expectedResults)
    {
        if(actual.Equals(expectedResult))
        {
            isExpectedResult = true;
        }
    }

    Assert.IsTrue(isExpectedResult, "The actual object '{0}' was not found in the expected results", actual);
}