【原创】Junit4详解一：Junit总体介绍
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IT文章
•
2025-01-23 15:58:49
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：
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1 import static org.junit.Assert.*;
2 2 public class TestCaculatorClass {
3 3 @Test
4 4 public void test() throws IOException, RuntimeException{
5 5 CaculatorClassForTest cal = new CaculatorClassForTest();
6 6 assertEquals(30, cal.sum(10, 20));
7 7 }
8 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。
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1 import static org.hamcrest.CoreMatchers.allOf;
2 import static org.hamcrest.CoreMatchers.anyOf;
3 import static org.hamcrest.CoreMatchers.equalTo;
4 import static org.hamcrest.CoreMatchers.not;
5 import static org.hamcrest.CoreMatchers.sameInstance;
6 import static org.hamcrest.CoreMatchers.startsWith;
7 import static org.junit.Assert.assertThat;
8 import static org.junit.matchers.JUnitMatchers.both;
9 import static org.junit.matchers.JUnitMatchers.containsString;
10 import static org.junit.matchers.JUnitMatchers.everyItem;
11 import static org.junit.matchers.JUnitMatchers.hasItems;
12
13 import java.util.Arrays;
14
15 import org.hamcrest.core.CombinableMatcher;
16 import org.junit.Test;
17
18 public class AssertTests {
19 @Test
20 public void testAssertArrayEquals() {
21 byte[] expected = "trial".getBytes();
22 byte[] actual = "trial".getBytes();
23 org.junit.Assert.assertArrayEquals("failure - byte arrays not same", expected, actual);
24 }
25
26 @Test
27 public void testAssertEquals() {
28 org.junit.Assert.assertEquals("failure - strings not same", 5l, 5l);
29 }
30
31 @Test
32 public void testAssertFalse() {
33 org.junit.Assert.assertFalse("failure - should be false", false);
34 }
35
36 @Test
37 public void testAssertNotNull() {
38 org.junit.Assert.assertNotNull("should not be null", new Object());
39 }
40
41 @Test
42 public void testAssertNotSame() {
43 org.junit.Assert.assertNotSame("should not be same Object", new Object(), new Object());
44 }
45
46 @Test
47 public void testAssertNull() {
48 org.junit.Assert.assertNull("should be null", null);
49 }
50
51 @Test
52 public void testAssertSame() {
53 Integer aNumber = Integer.valueOf(768);
54 org.junit.Assert.assertSame("should be same", aNumber, aNumber);
55 }
56
57 // JUnit Matchers assertThat
58 @Test
59 public void testAssertThatBothContainsString() {
60 org.junit.Assert.assertThat("albumen", both(containsString("a")).and(containsString("b")));
61 }
62
63 @Test
64 public void testAssertThathasItemsContainsString() {
65 org.junit.Assert.assertThat(Arrays.asList("one", "two", "three"), hasItems("one", "three"));
66 }
67
68 @Test
69 public void testAssertThatEveryItemContainsString() {
70 org.junit.Assert.assertThat(Arrays.asList(new String[] { "fun", "ban", "net" }), everyItem(containsString("n")));
71 }
72
73 // Core Hamcrest Matchers with assertThat
74 @Test
75 public void testAssertThatHamcrestCoreMatchers() {
76 assertThat("good", allOf(equalTo("good"), startsWith("good")));
77 assertThat("good", not(allOf(equalTo("bad"), equalTo("good"))));
78 assertThat("good", anyOf(equalTo("bad"), equalTo("good")));
79 assertThat(7, not(CombinableMatcher.<Integer> either(equalTo(3)).or(equalTo(4))));
80 assertThat(new Object(), not(sameInstance(new Object())));
81 }
82
83 @Test
84 public void testAssertTrue() {
85 org.junit.Assert.assertTrue("failure - should be true", true);
86 }
87 }
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。
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1 import org.junit.runner.RunWith;
2 import org.junit.runners.Suite;
3
4 @RunWith(Suite.class)
5 @Suite.SuiteClasses({
6 TestFeatureLogin.class,
7 TestFeatureLogout.class,
8 TestFeatureNavigate.class,
9 TestFeatureUpdate.class
10 })
11
12 public class FeatureTestSuite {
13 // the class remains empty,
14 // used only as a holder for the above annotations
15 }
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。
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1 package com.citi.risk.core.test.impl;
2
3 public class CaculatorClassForTest {
4
5 private int o1;
6 private int o2;
7 public int getO1() {
8 return this.o1;
9 }
10 public void setO1(int value) {
11 this.o1 = value;
12 }
13 public int getO2() {
14 return this.o2;
15 }
16 public void setO2(int value) {
17 this.o2 = value;
18 }
19
20
21 public CaculatorClassForTest() {}
22 public CaculatorClassForTest(int o1, int o2) {
23 this.o1 = o1;
24 this.o2 = o2;
25 }
26
27 public int sum(int o1, int o2){
28 if(o1 > 200) {
29 throw new RuntimeException("o1 is too big");
30 }
31 if(o2 > 200) {
32 throw new RuntimeException("o2 is too big");
33 }
34 int sum;
35 sum = o1 + o2;
36 return sum;
37 }
38 }
View CaculatorClassForTest Code
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1 package com.citi.risk.core.test.impl;
2
3 import static org.junit.Assert.*;
4
5 import java.io.IOException;
6 import java.util.List;
7
8 import org.junit.Rule;
9 import org.junit.Test;
10 import org.junit.rules.ExpectedException;
11 import org.junit.runner.RunWith;
12 import org.junit.runners.Parameterized;
13 import org.junit.runners.Parameterized.Parameter;
14 import org.junit.runners.Parameterized.Parameters;
15
16 import com.google.common.collect.Lists;
17
18 @RunWith(Parameterized.class)
19 public class TestCaculatorClass {
20 @Rule
21 public ExpectedException thrown = ExpectedException.none();
22
23 @Parameters
24 public static List<Object[]> data() {
25 return Lists.asList(new Object[]{-1, 1, 0}, new Object[][]{{20, 20, 40},{30, 30, 60},{-5, -5, -10}});
26 }
27 @Parameter(value = 0)
28 public int o1;
29 @Parameter(value = 1)
30 public int o2;
31 @Parameter(value = 2)
32 public int expector;
33
34 @Test
35 public void test() throws IOException, RuntimeException{
36 CaculatorClassForTest cal = new CaculatorClassForTest();
37 assertEquals(expector, cal.sum(o1, o2));
38 }
39
40 @Test
41 public void testO1Exception(){
42 CaculatorClassForTest cal = new CaculatorClassForTest();
43 thrown.expect(RuntimeException.class);
44 thrown.expectMessage("o1 is too big");
45 cal.sum(300, 100);
46 }
47 @Test
48 public void testO2Exception(){
49 CaculatorClassForTest cal = new CaculatorClassForTest();
50 thrown.expect(RuntimeException.class);
51 thrown.expectMessage("o2 is too big");
52 cal.sum(100, 300);
53 }
54
55 }
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。
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1 public interface FastTests { /* category marker */ }
2 public interface SlowTests { /* category marker */ }
3
4 public class A {
5 @Test
6 public void a() {
7 fail();
8 }
9
10 @Category(SlowTests.class)
11 @Test
12 public void b() {
13 }
14 }
15
16 @Category({SlowTests.class, FastTests.class})
17 public class B {
18 @Test
19 public void c() {
20
21 }
22 }
23
24 @RunWith(Categories.class)
25 @IncludeCategory(SlowTests.class)
26 @SuiteClasses( { A.class, B.class }) // Note that Categories is a kind of Suite
27 public class SlowTestSuite {
28 // Will run A.b and B.c, but not A.a
29 }
30
31 @RunWith(Categories.class)
32 @IncludeCategory(SlowTests.class)
33 @ExcludeCategory(FastTests.class)
34 @SuiteClasses( { A.class, B.class }) // Note that Categories is a kind of Suite
35 public class SlowTestSuite {
36 // Will run A.b, but not A.a or B.c
37 }
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：
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1 package abstractions.domain;
2
3 import java.io.Serializable;
4
5 import com.google.common.collect.ComparisonChain;
6
7 public class Address implements Serializable, Comparable<Address> {
8
9 private static final long serialVersionUID = 1L;
10 private final String address1;
11 private final String city;
12 private final String state;
13 private final String zip;
14
15 private Address(Builder builder) {
16 this.address1 = builder.address1;
17 this.city = builder.city;
18 this.state = builder.state;
19 this.zip = builder.zip;
20 }
21
22 public String getAddress1() {
23 return address1;
24 }
25
26 public String getCity() {
27 return city;
28 }
29
30 public String getState() {
31 return state;
32 }
33
34 public String getZip() {
35 return zip;
36 }
37
38 @Override
39 public int compareTo(Address that) {
40 return ComparisonChain.start().compare(this.zip, that.zip).compare(this.state, that.state)
41 .compare(this.city, that.city).compare(this.address1, that.address1).result();
42 }
43
44 @Override
45 public boolean equals(Object obj) {
46 if (obj == null) { return false; }
47 if (getClass() != obj.getClass()) { return false; }
48 final Address that = (Address) obj;
49
50 return com.google.common.base.Objects.equal(this.address1, that.address1)
51 && com.google.common.base.Objects.equal(this.city, that.city)
52 && com.google.common.base.Objects.equal(this.state, that.state)
53 && com.google.common.base.Objects.equal(this.zip, that.zip);
54 }
55
56 @Override
57 public int hashCode() {
58 return com.google.common.base.Objects.hashCode(getAddress1(), getCity(), getCity(), getState(), getZip());
59 }
60
61 @Override
62 public String toString() {
63 return com.google.common.base.Objects.toStringHelper(this).addValue(getAddress1()).addValue(getCity()).addValue(getState()).addValue(getZip()).toString();
64 }
65
66 public static class Builder {
67
68 private String address1;
69 private String city;
70 private String state;
71 private String zip;
72
73 public Builder address1(String address1) {
74 this.address1 = address1;
75 return this;
76 }
77
78 public Address build() {
79 return new Address(this);
80 }
81
82 public Builder city(String city) {
83 this.city = city;
84 return this;
85 }
86
87 public Builder state(String state) {
88 this.state = state;
89 return this;
90 }
91
92 public Builder zip(String zip) {
93 this.zip = zip;
94 return this;
95 }
96 }
97 }
View Address Code
test case：
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1 package abstractions.domain;
2
3 import static org.hamcrest.Matchers.is;
4 import static org.junit.Assert.assertThat;
5
6 import java.io.Serializable;
7
8 import org.junit.Before;
9 import org.junit.Test;
10 import org.junit.experimental.runners.Enclosed;
11 import org.junit.runner.RunWith;
12
13 import testhelpers.ComparabilityTestCase;
14 import testhelpers.EqualsHashCodeTestCase;
15 import testhelpers.SerializabilityTestCase;
16
17 /**
18 * The Class AddressTest.
19 */
20 @RunWith(Enclosed.class)
21 public class AddressTest {
22
23 /**
24 * The Class AddressComparabilityTest.
25 */
26 public static class AddressComparabilityTest extends ComparabilityTestCase<Address> {
27
28 @Override
29 protected Address createEqualInstance() throws Exception {
30 return new Address.Builder().address1("2802 South Havana Street").city("Aurora").state("CO").zip("80014").build();
31 }
32
33 @Override
34 protected Address createGreaterInstance() throws Exception {
35 return new Address.Builder().address1("9839 Carlisle Boulevard NE").city("Albuquerque").state("NM").zip("87110").build();
36 }
37
38 @Override
39 protected Address createLessInstance() throws Exception {
40 return new Address.Builder().address1("14 Broad St").city("Nashua").state("NH").zip("03064").build();
41 }
42 }
43
44 /**
45 * The Class AddressEqualsHashCodeTest.
46 */
47 public static class AddressEqualsHashCodeTest extends EqualsHashCodeTestCase {
48
49 @Override
50 protected Address createInstance() throws Exception {
51 return new Address.Builder().address1("2802 South Havana Street").city("Aurora").state("CO").zip("80014").build();
52 }
53
54 @Override
55 protected Address createNotEqualInstance() throws Exception {
56 return new Address.Builder().address1("9839 Carlisle Boulevard NE").city("Albuquerque").state("NM").zip("87110").build();
57 }
58 }
59
60 /**
61 * The Class AddressSerializabilityTest.
62 */
63 public static class AddressSerializabilityTest extends SerializabilityTestCase {
64
65 @Override
66 protected Serializable createInstance() throws Exception {
67 return new Address.Builder().address1("9839 Carlisle Boulevard NE").city("Albuquerque").state("NM").zip("87110").build();
68 }
69 }
70
71 public static class AddressMiscTest {
72
73 private Address address;
74
75 /**
76 * Setup.
77 *
78 * @throws Exception the exception
79 */
80 @Before
81 public void setUp() throws Exception {
82 address = new Address.Builder().address1("9839 Carlisle Boulevard NE").city("Albuquerque").state("NM").zip("87110").build();
83 }
84
85 /**
86 * Test builder.
87 */
88 @Test
89 public void testBuilder() {
90 assertThat(address.getAddress1(), is("9839 Carlisle Boulevard NE"));
91 assertThat(address.getCity(), is("Albuquerque"));
92 assertThat(address.getState(), is("NM"));
93 assertThat(address.getZip(), is("87110"));
94 }
95
96 @Test
97 public void testToString() {
98 assertThat(address.toString(), is("Address{9839 Carlisle Boulevard NE, Albuquerque, NM, 87110}"));
99 }
100 }
101 }
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。
1 @Ignore
2 public class TestClass{
3
4 @Ignore("Test is ignored as a demonstration")
5 @Test
6 public void testSane() {
7 assertThat(1, is(1));
8 }
9 }
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。
1 @Test(timeout=1000)
2 public void testWithTimeout() {
3 ...
4 }
Junit4还有更重要的@Rule 和 执行顺序。且听下回分解。
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