public void TestGetDrives() { var drives = new[] { new DriveInfo("A"), new DriveInfo("B"), new DriveInfo("C"), }; var envDriveServiceMock = new Mock <IEnvironmentDriveService>(); envDriveServiceMock .Setup(m => m.GetDrives()) .Returns(drives); var driveService = new DriveService(envDriveServiceMock.Object); var drivesModels = driveService.GetDrives(); Assert.NotNull(drivesModels); Assert.Equal(drives.Length, drivesModels.Count); }