Assert an Exception using XUnit
The Assert.Throws expression will catch the exception and assert the type. You are however calling the method under test outside of the assert expression and thus failing the test case.
[Fact]
public void ProfileRepository_GetSettingsForUserIDWithInvalidArguments_ThrowsArgumentException()
{
//arrange
ProfileRepository profiles = new ProfileRepository();
// act & assert
Assert.Throws<ArgumentException>(() => profiles.GetSettingsForUserID(""));
}
If bent on following AAA you can extract the action into its own variable.
[Fact]
public void ProfileRepository_GetSettingsForUserIDWithInvalidArguments_ThrowsArgumentException()
{
//arrange
ProfileRepository profiles = new ProfileRepository();
//act
Action act = () => profiles.GetSettingsForUserID("");
//assert
ArgumentException exception = Assert.Throws<ArgumentException>(act);
//The thrown exception can be used for even more detailed assertions.
Assert.Equal("expected error message here", exception.Message);
}
Note how the exception can also be used for more detailed assertions
If testing asynchronously, Assert.ThrowsAsync follows similarly to the previously given example, except that the assertion should be awaited,
public async Task Some_Async_Test() {
//...
//Act
Func<Task> act = () => subject.SomeMethodAsync();
//Assert
var exception = await Assert.ThrowsAsync<InvalidOperationException>(act);
//...
}
If you do want to be rigid about AAA then you can use Record.Exception from xUnit to capture the Exception in your Act stage.
You can then make assertions based on the captured exception in the Assert stage.
An example of this can be seen in xUnits tests.
[Fact]
public void Exception()
{
Action testCode = () => { throw new InvalidOperationException(); };
var ex = Record.Exception(testCode);
Assert.NotNull(ex);
Assert.IsType<InvalidOperationException>(ex);
}
It's up to you what path you want to follow, and both paths are fully supported by what xUnit provides.