Code inspection: NUnit. Test case source must be non-abstract and implement IEnumerable.

NUnit's TestCaseSource attribute is used to identify the source from which the argument(s) will be provided for a parameterized test. The class that provides test cases must have a default constructor and implement IEnumerable. If the test source class does not implement IEnumerable, JetBrains Rider issues a warning.

Note that NUnit allows different ways of specifying test case sources. For more information, refer to the TestCaseSourceAttribute documentation.