public void GetDataByGroupIdTest() { _repository .Setup(it => it.GetDataByGroupId(It.IsAny <Int32>())) .Returns <Int32>((groupId) => { return(_repositoryList.Where(x => x.GroupId == groupId).ToList()); }); var result = _target.GetDataByGroupId(groupIdValue).ToList(); Assert.AreEqual(_repositoryList.Where(x => x.GroupId == groupIdValue).ToList().Count, result.Count); }