public async Task GetAsyncById_ShouldReturnExerciseDto(int id)
{
var exercise = _fixture.Build <Exercise>()
.With(e => e.Id, id)
.Create();
_exerciseRepository.GetAsync(id).Returns(exercise);
var dto = await _sut.GetAsync(id);
dto.ShouldNotBeNull();
dto.Id.ShouldBe(exercise.Id);
dto.ShouldBeOfType(typeof(ExerciseDto));
await _exerciseRepository.Received(1).GetAsync(id);
}