C# System.Collections.Generic.First方法代码示例

 private IEnumerable<HTMLTag> GetSource()
 {
     IEnumerable<HTMLTag> source = new[] { this };
     if (source.Count() == 1 &&
         source.First().TypeEqualsIgnoreCase("html"))
     {
         source = source.First().ChildTags;
     }
     return source;
 }

        public void Accumulate_WithTwoEnumerations_AccumulatesOneIntoTheOther()
        {
            // arrange
            var containers = new[] { new KeyValuePair<int, List<string>>(0, new List<string>()), new KeyValuePair<int, List<string>>(1, new List<string>()), new KeyValuePair<int, List<string>>(2, new List<string>()), new KeyValuePair<int, List<string>>(3, new List<string>()) };
            var items = new[] {new KeyValuePair<int, string>(1, "A"), new KeyValuePair<int, string>(1, "B"), new KeyValuePair<int, string>(3, "C")};

            // act
            containers.Accumulate(items, container => container.Key, item => item.Key, (container, item) => container.Value.Add(item.Value));

            // assert
            Assert.AreEqual(0, containers.First().Value.Count);
            var secondContainer = containers.ElementAt(1);
            Assert.AreEqual(2, secondContainer.Value.Count);
            Assert.AreEqual("A", secondContainer.Value[0]);
            Assert.AreEqual("B", secondContainer.Value[1]);
            Assert.AreEqual(0, containers.ElementAt(2).Value.Count);
            var fourthContainer = containers.ElementAt(3);
            Assert.AreEqual(1, fourthContainer.Value.Count);
            Assert.AreEqual("C", fourthContainer.Value[0]);
        }

        private void GetGeometryColumnValue_returns_a_DbGeography(bool useSpatialReader)
        {
            var sourceEnumerable = new[] { new object[] { DbGeometry.FromText("POINT (90 50)") } };
            var reader = MockHelper.CreateDbDataReader(sourceEnumerable);

            var coordinatorFactory = Objects.MockHelper.CreateCoordinatorFactory(s => s.Reader.GetValue(0));

            var shaperMock = new Mock<Shaper<object>>(
                reader,
                /*context*/ null,
                /*workspace*/ null,
                MergeOption.AppendOnly,
                /*stateCount*/ 1,
                coordinatorFactory,
                /*readerOwned*/ false,
                /*useSpatialReader*/ useSpatialReader,
                /*shouldReleaseConnection*/ true)
                                 {
                                     CallBase = true
                                 };

            var spatialDataReaderMock = new Mock<DbSpatialDataReader>(MockBehavior.Strict);
            if (useSpatialReader)
            {
                spatialDataReaderMock.Setup(m => m.GetGeometry(0)).Returns((DbGeometry)sourceEnumerable.First()[0]);
            }
            shaperMock.Protected().Setup<DbSpatialDataReader>("CreateSpatialDataReader").Returns(spatialDataReaderMock.Object);

            reader.Read();

            Assert.Equal(sourceEnumerable.First()[0], shaperMock.Object.GetGeometryColumnValue(0));
            if (useSpatialReader)
            {
                spatialDataReaderMock.Verify(m => m.GetGeometry(0), Times.Once());
            }
        }

        public void GivenProgramWithServiceTypes_AndServiceTypesCanBeDuplicated_WhenExecuteDataSelector_ThenServiceTypeListMatches()
        {
            ProgramClientDataTable target = new ProgramClientDataTable(MockRequest);
            string[] expected = new[] { "Apple", "Orange", "Banana" };
            Program program = new Program
            {
                ServiceOfferings = expected.Select(name => new ServiceOffering { IsActive = true, ServiceType = new ServiceType { Name = name } }).ToList()
            };
            program.ServiceOfferings.Add(new ServiceOffering { IsActive = true, ServiceType = new ServiceType { Name = expected.First() } });

            dynamic actual = target.DataSelector.Compile().Invoke(program);

            CollectionAssert.AreEqual(expected, ((IEnumerable<string>)actual.ServiceTypes).ToList());
        }

        public void when_using_a_visitor()
        {
            //setup
            var controller = new PropertyBagVersionController<FlatPropertyBag>(TestHelper.CreateWithNonDefaultProperties<FlatPropertyBag>(), 
                                                                               _testHelper.MakeConfiguredCloneFactoryFor<FlatPropertyBag>(),
                                                                               _testHelper.EmptyChangeSet(),
                                                                               _testHelper.MakeConfiguredVisitorFactory(),
                                                                               _testHelper.MakeConfiguredProxyFactory());

            var fakeChildren = new[] {A.Fake<IVersionControlNode>(), A.Fake<IVersionControlNode>()};
            var fakeVisitor = A.Fake<IVersionControlTreeVisitor>();
            controller.Children.AddRange(fakeChildren);

            //act
            controller.Accept(fakeVisitor);

            //assert
            A.CallTo(() => fakeChildren.First().RecursiveAccept(fakeVisitor)).MustHaveHappened();
            A.CallTo(() => fakeChildren.Last().RecursiveAccept(fakeVisitor)).MustHaveHappened();
            A.CallTo(() => fakeVisitor.OnEntry(controller)).MustHaveHappened();
        }

        public void should_get_first_element_using_first()
        {
            var sequence = new[] { 1, 2, 3, 4, 5 };

            int firstElement = sequence.First();
            int firstEvenNumber = sequence.First(item => item % 2 == 0);

            // please update variable values for the following 2 lines to fix the test.
            const int expectedFirstElement = 0;
            const int expectedFirstEvenNumber = 0;

            Assert.Equal(expectedFirstElement, firstElement);
            Assert.Equal(expectedFirstEvenNumber, firstEvenNumber);
        }