public void Should_Throw_If_Adding_Source_That_Has_Already_Been_Added()
{
// Given
var fixture = new NuGetSourcesFixture();
fixture.Source = "existingsource";
fixture.GivenSourceAlreadyHasBeenAdded();
// When
var result = Record.Exception(() => fixture.AddSources());
// Then
Assert.IsType <InvalidOperationException>(result);
Assert.Equal("The source 'existingsource' already exist.", result.Message);
}