public async Task GetListModelAsync_WhenRepositoryIsNull_ThrowsArgumentNullException <TKey>(TKey defaultKey) { // Arrange & Act & Assert var exception = await Assert.ThrowsAsync <ArgumentNullException>( () => RepositoryExtensions.GetListAsync <FakeModel, IEntity <TKey>, TKey>(null, x => x.Id.Equals(defaultKey)) ); Assert.Equal("repository", exception.ParamName); }