public void GetInstrumentsByName_ValidId_ReturnsResult() { // Arrange var result = fixture.Create <IEnumerable <Instrument> >(); instrumentRepository.GetInstrumentsByName(Arg.Any <string>()).Returns(result); // Act var serviceResult = instrumentService.GetInstrumentsByName("test"); // Assert Assert.IsNotNull(serviceResult); Assert.AreEqual(serviceResult.Count(), result.Count()); }