NUnit–TestCase vs TestCaseSource

NUnit supports parameterized tests through the TestCase attribute. This allows you to specify multiple sets of arguments and will create multiple tests behind the scenes:

	[TestCase(12, 3, 4)]
	[TestCase(12, 2, 6)]
	[TestCase(12, 4, 3)]
	public void DivideTest(int n, int d, int q)
	{
	Assert.AreEqual(q, n / d);
	}

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However the kind of information that you can pass on through an attribute is rather limited. If you want to pass on complex objects you need a different solution. In that case (no pun intended) you can use the TestCaseSource attribute:

TestCaseSourceAttribute is used on a parameterized test method to identify the source from which the required arguments will be provided. The attribute additionally identifies the method as a test method. The data is kept separate from the test itself and may be used by multiple test methods.

An example:

	[TestCaseSource("TestCases")]
	public async Task GetOrders(Guid correlationId, Customer customer, int expectedCount)
	{
	//Act
	var orders = await _sut.GetOrders(transportDocument);
	//Assert
	Assert.IsNotNull(orders);
	Assert.AreEqual(expectedCount, orders.Count);
	}
	private static readonly object[] TestCases =
	{
	new object[]{ Guid.NewGuid(), new Customer(){Id=1}, 1 },
	new object[]{ Guid.NewGuid(), new Customer(){Id=1}, 1 },
	new object[]{ Guid.NewGuid(), new Customer(){Id=1}, 1 },
	new object[]{ Guid.NewGuid(), new Customer(){Id=1}, 3 }
	};

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