How to express an expected call on a Moq mock in the memberdata for an XUnit Theory.

In XUnit you can use the [Theory] attribute to run the same test against a set of different parameters. Moq allows you to specify expectations on which methods of a mocked interface are called, with the Verify method. Recently, I wanted to combine these two techniques to be able to convey the expectation along with the other test parameters to the XUnit Theory. It took me a little thought to get this right. The trick is in casting the expected call (usually an Action<T>) to an Expression<Action<T>>. That is done in the gist below.

Simply check logged messages in .NET Core and Moq

The Microsoft.Extensions.Logging framework in ASP.NET Core is very useful for logging, but it can be somewhat verbose to check logged messages in your unit tests. Because the methods you use for logging (LogInformation, LogWarning etc.) are all extension methods, you cannot verify calls on them. You can verify calls to the Log method. But it took me some time to find out what the exact check should be. So I wrapped that knowledge into a utility method VerifyLog, in this Gist: Happy logging!