public async void GetAllAsync_ShouldReturnListOfEmployees() { // Arrange var employees = new List <Pet> { new Pet { Id = 21, Name = "Dick", Type = "duck", OwnerId = 23 }, new Pet { Id = 12, Name = "Mat", Type = "cat", OwnerId = 48 } }; var options = new DbContextOptionsBuilder <AppContext>() .UseInMemoryDatabase(databaseName: "Pets1") .Options; using (var appContext = new AppContext(options)) { await appContext.Pets.AddRangeAsync(employees); await appContext.SaveChangesAsync(); } using (var appContext = new AppContext(options)) { var repo = new PetsRepository(appContext); // Act var result = await repo.GetAllAsync(); // Assert Assert.IsAssignableFrom <IEnumerable <Pet> >(result); Assert.Equal(employees.Count, result.Count()); } }