public async Task GetAllGroupsAsync_CallsRepositoryCorrectly()
{
var groups = _fixture.CreateMany <Group>(5).ToList();
_mockRepository.Setup(repo => repo.GetAllGroupsAsync())
.ReturnsAsync(groups);
var result = await SUT.GetAllGroupsAsync();
_mockRepository.Verify(repo => repo.GetAllGroupsAsync(), Times.Once);
result.ShouldBe(groups);
}