【原创】Junit4详解一：Junit总体介绍

Junit是一个可编写重复测试的简单框架，是基于Xunit架构的单元测试框架的实例。Junit4最大的改进是大量使用注解（元数据），很多实际执行过程都在Junit的后台做完了，而且写test case 的类不需要继承TestCase，只需要在所要做test case的方法前加@Test 注解即可。

如：

 import static org.junit.Assert.*;
 2 public class TestCaculatorClass {
 3     @Test
 4     public void test() throws IOException, RuntimeException{
 5         CaculatorClassForTest cal = new CaculatorClassForTest();
 6         assertEquals(30, cal.sum(10, 20));
 7     }
 8 }

View @Test Code

直接点击右键，run as... Junit Test即可运行此test case。

Assert类里面有很多assert方法，包括：assertEquals()， assertNotNull()，assertTtrue()，assertFalse()，assertThat()等，其中assertThat用的是match的形式。

因此，Junit提供很多中Match，其中CoreMatchers是其中一个比较完善的实现类。具体有上面方法可以查阅CoreMatchers类。

 import static org.hamcrest.CoreMatchers.allOf;
 import static org.hamcrest.CoreMatchers.anyOf;
 import static org.hamcrest.CoreMatchers.equalTo;
 import static org.hamcrest.CoreMatchers.not;
 import static org.hamcrest.CoreMatchers.sameInstance;
 import static org.hamcrest.CoreMatchers.startsWith;
 import static org.junit.Assert.assertThat;
 import static org.junit.matchers.JUnitMatchers.both;
 import static org.junit.matchers.JUnitMatchers.containsString;
 import static org.junit.matchers.JUnitMatchers.everyItem;
 import static org.junit.matchers.JUnitMatchers.hasItems;

 import java.util.Arrays;

 import org.hamcrest.core.CombinableMatcher;
 import org.junit.Test;

 public class AssertTests {
   @Test
   public void testAssertArrayEquals() {
     byte[] expected = "trial".getBytes();
     byte[] actual = "trial".getBytes();
     org.junit.Assert.assertArrayEquals("failure - byte arrays not same", expected, actual);
   }

   @Test
   public void testAssertEquals() {
     org.junit.Assert.assertEquals("failure - strings not same", 5l, 5l);
   }

   @Test
   public void testAssertFalse() {
     org.junit.Assert.assertFalse("failure - should be false", false);
   }

   @Test
   public void testAssertNotNull() {
     org.junit.Assert.assertNotNull("should not be null", new Object());
   }

   @Test
   public void testAssertNotSame() {
     org.junit.Assert.assertNotSame("should not be same Object", new Object(), new Object());
   }

   @Test
   public void testAssertNull() {
     org.junit.Assert.assertNull("should be null", null);
   }

   @Test
   public void testAssertSame() {
     Integer aNumber = Integer.valueOf(768);
     org.junit.Assert.assertSame("should be same", aNumber, aNumber);
   }

   // JUnit Matchers assertThat
   @Test
   public void testAssertThatBothContainsString() {
     org.junit.Assert.assertThat("albumen", both(containsString("a")).and(containsString("b")));
   }

   @Test
   public void testAssertThathasItemsContainsString() {
     org.junit.Assert.assertThat(Arrays.asList("one", "two", "three"), hasItems("one", "three"));
   }

   @Test
   public void testAssertThatEveryItemContainsString() {
     org.junit.Assert.assertThat(Arrays.asList(new String[] { "fun", "ban", "net" }), everyItem(containsString("n")));
   }

   // Core Hamcrest Matchers with assertThat
   @Test
   public void testAssertThatHamcrestCoreMatchers() {
     assertThat("good", allOf(equalTo("good"), startsWith("good")));
     assertThat("good", not(allOf(equalTo("bad"), equalTo("good"))));
     assertThat("good", anyOf(equalTo("bad"), equalTo("good")));
     assertThat(7, not(CombinableMatcher.<Integer> either(equalTo(3)).or(equalTo(4))));
     assertThat(new Object(), not(sameInstance(new Object())));
   }

   @Test
   public void testAssertTrue() {
     org.junit.Assert.assertTrue("failure - should be true", true);
   }
 }

View Assert Code

问题一，我可不可以把多个测试类放在一起执行？

回答： 可以。org.junit.runner.JUnitCore.runClasses(TestClass1.class, ...);利用这样，把test case 的类放进去，然后放在main()方法里执行。

问题二，@RunWith这个注解有什么作用？

回答：Junit4的默认runner为BlockJunit4ClassRunner，但是Junit4包括第三方软件还提供很多其他的runner，这样如果，我们想让我们的测试类用专门的runner来运行，这时候就可以用@RunWith(Suit.class

)标注测试类。其他特殊的runner有：

1. Suite： 字面理解是一个套装，通俗地讲，就是你可以把很多测试类放在一起，然后建一个类，标注为Suite.class，那么如果执行这个类，就会把所有的测试类一起执行。

 import org.junit.runner.RunWith;
 import org.junit.runners.Suite;

 @RunWith(Suite.class)
 @Suite.SuiteClasses({
   TestFeatureLogin.class,
   TestFeatureLogout.class,
   TestFeatureNavigate.class,
   TestFeatureUpdate.class
 })

 public class FeatureTestSuite {
   // the class remains empty,
   // used only as a holder for the above annotations
 }

View Suite Code

2. Parameterized：根据所设计的参数来执行测试。假设我们要测试某一个方法，它有两个参数，每个参数需要设计不同值，那么我们最开始就是需要为每个参数设计一个测试方法，这样就很麻烦，10种case就得10个方法，但是有了Parameterized runner，我们可以设计一个方法，多种参数来执行test case。

 package com.citi.risk.core.test.impl;

 public class CaculatorClassForTest {

     private int o1;
     private int o2;
     public int getO1() {
         return this.o1;
     }
     public void setO1(int value) {
         this.o1 = value;
     }
     public int getO2() {
         return this.o2;
     }
     public void setO2(int value) {
         this.o2 = value;
     }

     public CaculatorClassForTest() {}
     public CaculatorClassForTest(int o1, int o2) {
         this.o1 = o1;
         this.o2 = o2;
     }

     public int sum(int o1, int o2){
         if(o1 > 200) {
             throw new RuntimeException("o1 is too big");
         }
         if(o2 > 200) {
             throw new RuntimeException("o2 is too big");
         }
         int sum;
         sum = o1 + o2;
         return sum;
     }
 }

View CaculatorClassForTest Code

 package com.citi.risk.core.test.impl;

 import static org.junit.Assert.*;

 import java.io.IOException;
 import java.util.List;

 import org.junit.Rule;
 import org.junit.Test;
 import org.junit.rules.ExpectedException;
 import org.junit.runner.RunWith;
 import org.junit.runners.Parameterized;
 import org.junit.runners.Parameterized.Parameter;
 import org.junit.runners.Parameterized.Parameters;

 import com.google.common.collect.Lists;

 @RunWith(Parameterized.class)
 public class TestCaculatorClass {
     @Rule
     public ExpectedException thrown = ExpectedException.none();

     @Parameters
     public static List<Object[]> data() {
         return Lists.asList(new Object[]{-1, 1, 0}, new Object[][]{{20, 20, 40},{30, 30, 60},{-5, -5, -10}});
     }
     @Parameter(value = 0)
     public int o1;
     @Parameter(value = 1)
     public int o2;
     @Parameter(value = 2)
     public int expector;

     @Test
     public void test() throws IOException, RuntimeException{
         CaculatorClassForTest cal = new CaculatorClassForTest();
         assertEquals(expector, cal.sum(o1, o2));
     }

     @Test
     public void testO1Exception(){
         CaculatorClassForTest cal = new CaculatorClassForTest();
         thrown.expect(RuntimeException.class);
         thrown.expectMessage("o1 is too big");
         cal.sum(300, 100);
     }
     @Test
     public void testO2Exception(){
         CaculatorClassForTest cal = new CaculatorClassForTest();
         thrown.expect(RuntimeException.class);
         thrown.expectMessage("o2 is too big");
         cal.sum(100, 300);
     }

 }

View TestCaculatorClass Code

以上两个类就是测试了Parameterized runner， 参数会自动匹配。它其实就是，看我们传入几种case， 也就是List.size()，然后，把类里面的方法，循环重复执行size()数目。

3. Categories：容易理解就是分类执行。假设我们有一种case： 我们写好了两个测试类，类A，类B，A有两个方法a(), b(),这时候我们有一个类来执行这两个类的test case，但是我们在类A里只想执行A.b()，但却不执行A.a()，这个时候我们可以用Categories runner。

 public interface FastTests { /* category marker */ }
 public interface SlowTests { /* category marker */ }

 public class A {
   @Test
   public void a() {
     fail();
   }

   @Category(SlowTests.class)
   @Test
   public void b() {
   }
 }

 @Category({SlowTests.class, FastTests.class})
 public class B {
   @Test
   public void c() {

   }
 }

 @RunWith(Categories.class)
 @IncludeCategory(SlowTests.class)
 @SuiteClasses( { A.class, B.class }) // Note that Categories is a kind of Suite
 public class SlowTestSuite {
   // Will run A.b and B.c, but not A.a
 }

 @RunWith(Categories.class)
 @IncludeCategory(SlowTests.class)
 @ExcludeCategory(FastTests.class)
 @SuiteClasses( { A.class, B.class }) // Note that Categories is a kind of Suite
 public class SlowTestSuite {
   // Will run A.b, but not A.a or B.c
 }

View Categories Code

4. Enclosed：如果我们把tests放在了内部类，这时候执行外部类是无法执行里面的test cases，这种情况下，就应该在outer class 用Enclosed runner。

要测试的类 Address：

 package abstractions.domain;

     import java.io.Serializable;

     import com.google.common.collect.ComparisonChain;

     public class Address implements Serializable, Comparable<Address> {

         private static final long serialVersionUID = 1L;
         private final String address1;
         private final String city;
         private final String state;
         private final String zip;

         private Address(Builder builder) {
             this.address1 = builder.address1;
             this.city = builder.city;
             this.state = builder.state;
             this.zip = builder.zip;
         }

         public String getAddress1() {
             return address1;
         }

         public String getCity() {
             return city;
         }

         public String getState() {
             return state;
         }

         public String getZip() {
             return zip;
         }

         @Override
         public int compareTo(Address that) {
             return ComparisonChain.start().compare(this.zip, that.zip).compare(this.state, that.state)
                     .compare(this.city, that.city).compare(this.address1, that.address1).result();
         }

         @Override
         public boolean equals(Object obj) {
             if (obj == null) { return false; }
             if (getClass() != obj.getClass()) { return false; }
             final Address that = (Address) obj;

             return com.google.common.base.Objects.equal(this.address1, that.address1)
                     && com.google.common.base.Objects.equal(this.city, that.city)
                     && com.google.common.base.Objects.equal(this.state, that.state)
                     && com.google.common.base.Objects.equal(this.zip, that.zip);
         }

         @Override
         public int hashCode() {
             return com.google.common.base.Objects.hashCode(getAddress1(), getCity(), getCity(), getState(), getZip());
         }

         @Override
         public String toString() {
             return com.google.common.base.Objects.toStringHelper(this).addValue(getAddress1()).addValue(getCity()).addValue(getState()).addValue(getZip()).toString();
         }

         public static class Builder {

             private String address1;
             private String city;
             private String state;
             private String zip;

             public Builder address1(String address1) {
                 this.address1 = address1;
                 return this;
             }

             public Address build() {
                 return new Address(this);
             }

             public Builder city(String city) {
                 this.city = city;
                 return this;
             }

             public Builder state(String state) {
                 this.state = state;
                 return this;
             }

             public Builder zip(String zip) {
                 this.zip = zip;
                 return this;
             }
         }
     }

View Address Code

test case：

 package abstractions.domain;

     import static org.hamcrest.Matchers.is;
     import static org.junit.Assert.assertThat;

     import java.io.Serializable;

     import org.junit.Before;
     import org.junit.Test;
     import org.junit.experimental.runners.Enclosed;
     import org.junit.runner.RunWith;

     import testhelpers.ComparabilityTestCase;
     import testhelpers.EqualsHashCodeTestCase;
     import testhelpers.SerializabilityTestCase;

     /**
      * The Class AddressTest.
      */
     @RunWith(Enclosed.class)
     public class AddressTest {

         /**
          * The Class AddressComparabilityTest.
          */
         public static class AddressComparabilityTest extends ComparabilityTestCase<Address> {

             @Override
             protected Address createEqualInstance() throws Exception {
                 return new Address.Builder().address1("2802 South Havana Street").city("Aurora").state("CO").zip("80014").build();
             }

             @Override
             protected Address createGreaterInstance() throws Exception {
                 return new Address.Builder().address1("9839 Carlisle Boulevard NE").city("Albuquerque").state("NM").zip("87110").build();
             }

             @Override
             protected Address createLessInstance() throws Exception {
                 return new Address.Builder().address1("14 Broad St").city("Nashua").state("NH").zip("03064").build();
             }
         }

         /**
          * The Class AddressEqualsHashCodeTest.
          */
         public static class AddressEqualsHashCodeTest extends EqualsHashCodeTestCase {

             @Override
             protected Address createInstance() throws Exception {
                 return new Address.Builder().address1("2802 South Havana Street").city("Aurora").state("CO").zip("80014").build();
             }

             @Override
             protected Address createNotEqualInstance() throws Exception {
                 return new Address.Builder().address1("9839 Carlisle Boulevard NE").city("Albuquerque").state("NM").zip("87110").build();
             }
         }

         /**
          * The Class AddressSerializabilityTest.
          */
         public static class AddressSerializabilityTest extends SerializabilityTestCase {

             @Override
             protected Serializable createInstance() throws Exception {
                 return new Address.Builder().address1("9839 Carlisle Boulevard NE").city("Albuquerque").state("NM").zip("87110").build();
             }
         }

         public static class AddressMiscTest {

             private Address address;

             /**
              * Setup.
              *
              * @throws Exception the exception
              */
             @Before
             public void setUp() throws Exception {
                 address = new Address.Builder().address1("9839 Carlisle Boulevard NE").city("Albuquerque").state("NM").zip("87110").build();
             }

             /**
              * Test builder.
              */
             @Test
             public void testBuilder() {
                 assertThat(address.getAddress1(), is("9839 Carlisle Boulevard NE"));
                 assertThat(address.getCity(), is("Albuquerque"));
                 assertThat(address.getState(), is("NM"));
                 assertThat(address.getZip(), is("87110"));
             }

             @Test
             public void testToString() {
                 assertThat(address.toString(), is("Address{9839 Carlisle Boulevard NE, Albuquerque, NM, 87110}"));
             }
         }
     }

View AddressTest Code

问题三：不想执行某个类的test case 有什么方法？

回答： 用@Ignore， 如果要让某个类都不执行，@Ignore放在类里，如果不想执行某一个方法，只需要放在方法上。

 @Ignore
 public class TestClass{

     @Ignore("Test is ignored as a demonstration")
     @Test
     public void testSane() {
         assertThat(1, is(1));
     }
 }

问题四：某个test case执行时间太长，有什么办法终止？

回答： Junit4提供了timeout属性。

 @Test(timeout=1000)
 public void testWithTimeout() {
   ...
 }

Junit4还有更重要的@Rule 和 执行顺序。且听下回分解。

 

草原战狼淘宝小店：http://xarxf.taobao.com/ 淘宝搜小矮人鞋坊，主营精致美丽时尚女鞋，为您的白雪公主挑一双哦。谢谢各位博友的支持。

===============================================================================

==========================    以上分析仅代表个人观点，欢迎指正与交流   ==========================

==========================    草原战狼博客，转载请注明出处，万分感谢   ==========================

===============================================================================