Can someone not work out a way to 'unit test' dependency injection vs other methods so we have some facts to compare? These discussions feel like people arguing

Can someone not work out a way to 'unit test' dependency injection vs other methods so we have some facts to compare? These discussions feel like people arguing with each other over which color is the best, with everyone chiming in with random anecdotes and feelings. Red must be the best - it goes the fastest!