public async Task DeleteAllAsync_Success() { // Arrange var items = new List <Author>() { new Author() { Name = "name", Surname = "surname", BornDate = "01-01-1970", Country = "TEST" }, new Author() { Name = "name1", Surname = "surname1", BornDate = "01-01-1970", Country = "TEST" }, new Author() { Name = "name2", Surname = "surname2", BornDate = "01-01-1970", Country = "TEST" } }; items.ForEach(x => db.AddItemAsync(x).ConfigureAwait(true)); Assert.AreEqual(items.Count, db.GetItemsAsync().Result.Count); // Act await db.DeleteAllAsync(); // Assert Assert.AreEqual(0, db.GetItemsAsync().Result.Count); }