Introduction
The single most powerful feature of NUnit, is arguably its extensive support for Data-Driven Tests through attributes like [TestCase], [TestCaseSource], and [ValueSource].
This feature allows for parameterised tests, enabling developers to run the same test method with different inputs and expected outputs, vastly increasing the test coverage and maintainability of test code.
Data-Driven Testing in NUnit
[TestCase] Attribute:
[Test]
[TestCase(1, 2, 3)]
[TestCase(3, 4, 7)]
public void AddTest(int a, int b, int expected)
{
Assert.That(MyMath.Add(a, b), Is.EqualTo(expected));
}[TestCaseSource] Attribute:
private static IEnumerable<TestCaseData> AddTestCases
{
get
{
yield return new TestCaseData(1, 2).Returns(3);
yield return new TestCaseData(3, 4).Returns(7);
}
}
[Test, TestCaseSource(nameof(AddTestCases))]
public int AddTest(int a, int b)
{
return MyMath.Add(a, b);
}[ValueSource] Attribute:
[Test]
public void MyTest([ValueSource(nameof(MyValues))] int x)
{
// Test logic here
}Why It’s Powerful
- Increased Test Coverage and Efficiency: Allows testing a wide range of inputs and scenarios with a single test method, reducing code duplication and increasing coverage.
- Maintainability: Easier to maintain and update tests, as changes in logic only need to be reflected in one place.
- Flexibility: Accommodates complex testing scenarios with different types of data sources.
- Readability: Makes tests more readable and organised, especially when dealing with multiple test cases.
Conclusion
NUnit’s data-driven testing capabilities make it a powerful tool for developers, allowing for efficient and thorough testing across a multitude of scenarios with minimal code repetition.
This feature significantly enhances the effectiveness of the testing process in software development.
The official documentation for NUnit can be found here: – https://docs.nunit.org/articles/nunit/intro.html.
I have written a number of posts about NUnit here: – Asynchronous Testing with NUnit and C#, Using NUnit to test Exceptions, NUnit Assert.That.
