.NET单元测试学习(二)

二、基于约束的断言模式（Constraint-Based Assert Model）

    基于约束的断言模式只有一种方式来完成所有的断言，即Assert.That([],[]). 第二个参数才是完成断言的重要逻辑。

在VS2005中使用此模式需引用三个命名空间： using NUnit.Framework;                                                            using NUnit.Framework.Constraints;                                                            using NUnit.Framework.SyntaxHelpers;

     1、Equal Constraint

     用于测试当前值与期望值相等。如Assert.That(myvalue,Is EqualTo(Expectedvalue)); 如果两个不同数值类型的值相同则测试也会通过。float 与double的比较需要另外添加一个参数来指出两者之间的允许公差，在此公差之类则会测试通过。如：Assert.That( 2.1 + 1.2, Is.EqualTo( 3.3 ).Within( .0005 );.  当然在NUnit2.4.2之后，Within 表示的公差也可用于别的类型之间的比较。   另外，float的NaN值也可以跟NaN值比较，Assert.That( double.NaN, Is.EqualTo( double.NaN ) );此时测试通过。   要比较两个相同维度、相同元素、相同类型的数组，需要加上AsCollection修饰符，即Assert.That( array2x2, Is.EqualTo( array4 ).AsCollection ); 如果不加则测试失败。   如果比较两个字符类型，且需要忽略大小则添加IgnoreCase修饰符，同时也可以用于字符型数组或集合。          如：Assert.That( actual, Is.EqualTo( expected ).IgnoreCase;        2、Same As Constraint

     用于测试两个对象是否相同，前面已经说过相同的概念，同Assert.AreSame()/Assert.AreNotSame()。如：      [Test]      public void SameAsTest()      {          //定义变量         var ex1 = new Exception();         var ex2 = ex1;         var ex3 = new Exception();         //约束语法         Assert.That(ex2, Is.SameAs(ex1));         Assert.That(ex3, Is.Not.SameAs(ex1));         //使用继承语法         Expect(ex2, SameAs(ex1));         Expect(ex3, Not.SameAs(ex1));    }

    3、Condition Constraint    条件测试提供了测试一个对象是否为空、引用为空、是否为真等行为。如：          Assert.That( anObject, Is.Null );          Assert.That( anObject, Is.Not.Null );          Assert.That( condition, Is.True );          Assert.That( condition, Is.False );          Assert.That( aDouble, Is.NaN );          Assert.That( aDouble, Is.Not.NaN );          Assert.That( aString, Is.Empty );          Assert.That( collection, Is.Empty );          Assert.That( collection, Is.Unique );          Expect( aDouble, NaN );          Expect( collection, Unique );

    4、Comparsion Constraint     两个数值之间的比较。如：     Assert.That(7, Is.GreaterThan(3));  //大于     Assert.That(7, Is.GreaterThanOrEqualTo(3));   //大于等于     Assert.That(7, Is.AtLeast(3));    //最少     Assert.That(7, Is.GreaterThanOrEqualTo(7));        Assert.That(7, Is.AtLeast(7));     Assert.That(3, Is.LessThan(7));//小于     Assert.That(3, Is.LessThanOrEqualTo(7));        Assert.That(3, Is.AtMost(7));   //最多     Assert.That(3, Is.LessThanOrEqualTo(3));     Assert.That(3, Is.AtMost(3));     Expect( 7, GreaterThan(3));                 // Using Inheritance     Expect( 3, AtMost(7));

    5、Type Constraint    用于测试对象类型；

      Assert.That("Hello", Is.TypeOf(typeof(string))); //当前对象类型是否为了期望类型            Assert.That("Hello", Is.Not.TypeOf(typeof(int)));       Assert.That("Hello", Is.InstanceOfType(typeof(string))); //当前对象类型是否为期望类型的实例            Assert.That(5, Is.Not.InstanceOfType(typeof(string)));       Assert.That( "Hello", Is.AssignableFrom(typeof(string)));//是否为期望类型所指定的类型       Assert.That( 5, Is.Not.AssignableFrom(typeof(string)));       // Using inheritance       Expect( 5, Not.InstanceOfType(typeof(string)));       Expect( "Hello", AssignableFrom(typeOf(string)));  6、String Constraint 字符串约束；如：      string phrase = "Make your tests fail before passing!"      Assert.That( phrase, Text.Contains( "tests fail" ) );      Assert.That( phrase, Text.Contains( "make" ).IgnoreCase );      Assert.That( phrase, Text.StartsWith( "Make" ) );      Assert.That( phrase, Text.Not.StartsWith( "Break" ) );      Assert.That( phrase, Text.DoesNotStartWith( "Break" ) );      Assert.That( phrase, Text.EndsWith( "!" ) );      Assert.That( phrase, Text.EndsWith( "PASSING!" ).IgnoreCase );      Assert.That( phrase, Text.Matches( "Make.*tests.*pass" ) );      Assert.That( phrase, Text.Not.Matches( "your.*passing.*tests" ) );      Assert.That( phrase, Text.DoesNotMatch( "your.*passing.*tests" ) );      // Using Inheritance      Expect( phrase, Contains( "make" ).IgnoreCase );      Expect( phrase, EndsWith( "!" ) );      Expect( phrase, Matches( "Make.*pass" ) ); 7、Collection Constraint     集合结束为指定的集合执行测试，主要的语法有：     Is.All...,Has.All...  为集合中的每一个元素申请一个约束，所有元素符合要求则测试成功。     Has.Some...   为集合中的每一个元素申请约束，最少有一个符合要求则测试成功。     Has.None...    所有的元素都不都不符合要求则测试成功。     Is.Unique       测试集合拥有一个唯一值     Has.Member(object)    测试集合拥有一个对象     Is.EquivalentTo(IEnumerable)  测试两个集合相等,需要拥有相同的items.     Is.SubsetOf(IEnumerable)       测试一个集合是否是另一个的子集          int[] iarray = new int[] { 1, 2, 3 };          string[] sarray = new string[] { "a", "b", "c" };          Assert.That( iarray, Is.All.Not.Null );          Assert.That( sarray, Is.All.InstanceOfType(typeof(string)) );          Assert.That( iarray, Is.All.GreaterThan(0) );          Assert.That( sarray, Is.Unique );          Assert.That( iarray, List.Contains(3) );          Assert.That( sarray, List.Contains("b") );          Assert.That( sarray, List.Not.Contains("x") );          Assert.That( new string[] { "c", "a", "b" }, Is.EquivalentTo( sarray ) );          Assert.That( new int[] { 1, 2, 2 }, Is.Not.EquivalentTo( iarray ) );          Assert.That( new int[] { 1, 3 }, Is.SubsetOf( iarray ) );          // Using inheritance          Expect( iarray, All.GreaterThan( 0 ) );          Expect( sarray, Contains("b") );          Expect( new int[] { 1, 3 }, SubsetOf( iarray ) );

     8、Property Constraint     测试对象的属性。Has.Property(string)   //测试指定对象是否存在               Has.Property(string,object)   //测试对象属性值是否与提供的值相等               Has.Lenght(int)   // 测试对象的长度是否与指定的值相等               Has.Count(int)     //测试对象的总数是否与指定的值相等           ArrayList arrayList1 = new ArrayList();            arrayList1.Add("ccnu");            arrayList1.Add("whu");            arrayList1.Add("hsut");            int[] array = new int[8] {0,1,2,3,4,5,6,7 };            NUnit.Framework.Assert.That(array,Has.Property ("Length"));            NUnit.Framework.Assert.That(array,Has.Property ("Length").EqualTo(8));            NUnit.Framework.Assert.That(array,Has.Length (8));            //Array has not Property Count            //NUnit.Framework.Assert.That(array,Has.Count (8)); // Fail            NUnit.Framework.Assert.That(arrayList1,Has .Property ("Count"));            NUnit.Framework.Assert.That(arrayList1,Has.Count(3));