在单元测试方面，是个菜鸟，慢慢积累吧。
案例一：
测试私有方法，
1.含有私有方法的类
package com.test.blue;
public class SayHelloService {
private String sayHi() {
return "hello ,today is Wednesday!";
}
}
2. Test Case
package com.test.blue;
import org.junit.Assert;
import org.junit.Test;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
public class SayHelloServiceTest {
@Test
public void should_return_string_successfully() throws NoSuchMethodException, InvocationTargetException, IllegalAccessException {
Class<SayHelloService> classType = SayHelloService.class;
Method method = classType.getDeclaredMethod("sayHi",new Class[]{}); //其中sayHi是方法名，参数存于new Class[]{},的大括号中
method.setAccessible(true);
String str= (String) method.invoke(new SayHelloService(),null); //没有参数，则传null
Assert.assertEquals("hello ,today is Wednesday!",str);
}
}
案例二：
测试的私有方法抛异常的情况
现在给SayHelloService增加一个私有方法getNumber
private Integer getNumber(Integer num){
return num/0;
}然后针对该私有方法写testcase
@Test
public void should_throw_exception() throws NoSuchMethodException, InvocationTargetException, IllegalAccessException {
SayHelloService sayHelloService = new SayHelloService();
Class<SayHelloService> classType = SayHelloService.class;
Method method = classType.getDeclaredMethod("getNumber", new Class[]{Integer.class});
method.setAccessible(true); // 抑制Java对修饰符的检查
method.invoke(sayHelloService, new Object[]{1});
}然后运行test case，失败，出现错误如下：
/Library/Java/JavaVirtualMachines/jdk1.8.0_162.jdk/Contents/Home/bin/java -ea -Didea.test.cyclic.buffer.size=1048576 "-javaagent:/Applications/IntelliJ IDEA.app/Contents/lib/idea_rt.jar=53461:/Applications/IntelliJ IDEA.app/Contents/bin" -Dfile.encoding=UTF-8 -classpath "/Applications/IntelliJ IDEA.app/Contents/lib/idea_rt.jar:/Applications/IntelliJ IDEA.app/Contents/plugins/junit/lib/junit-rt.jar:/Applications/IntelliJ IDEA.app/Contents/plugins/junit/lib/junit5-rt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_162.jdk/Contents/Home/jre/lib/charsets.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_162.jdk/Contents/Home/jre/lib/deploy.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_162.jdk/Contents/Home/jre/lib/ext/cldrdata.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_162.jdk/Contents/Home/jre/lib/ext/dnsns.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_162.jdk/Contents/Home/jre/lib/ext/jaccess.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_162.jdk/Contents/Home/jre/lib/ext/jfxrt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_162.jdk/Contents/Home/jre/lib/ext/localedata.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_162.jdk/Contents/Home/jre/lib/ext/nashorn.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_162.jdk/Contents/Home/jre/lib/ext/sunec.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_162.jdk/Contents/Home/jre/lib/ext/sunjce_provider.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_162.jdk/Contents/Home/jre/lib/ext/sunpkcs11.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_162.jdk/Contents/Home/jre/lib/ext/zipfs.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_162.jdk/Contents/Home/jre/lib/javaws.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_162.jdk/Contents/Home/jre/lib/jce.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_162.jdk/Contents/Home/jre/lib/jfr.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_162.jdk/Contents/Home/jre/lib/jfxswt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_162.jdk/Contents/Home/jre/lib/jsse.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_162.jdk/Contents/Home/jre/lib/management-agent.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_162.jdk/Contents/Home/jre/lib/plugin.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_162.jdk/Contents/Home/jre/lib/resources.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_162.jdk/Contents/Home/jre/lib/rt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_162.jdk/Contents/Home/lib/ant-javafx.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_162.jdk/Contents/Home/lib/dt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_162.jdk/Contents/Home/lib/javafx-mx.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_162.jdk/Contents/Home/lib/jconsole.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_162.jdk/Contents/Home/lib/packager.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_162.jdk/Contents/Home/lib/sa-jdi.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_162.jdk/Contents/Home/lib/tools.jar:/Users/hfguan/workspace/cbs-workspace/blue/out/test/classes:/Users/hfguan/workspace/cbs-workspace/blue/out/production/classes:/Users/hfguan/.gradle/caches/modules-2/files-2.1/org.springframework.boot/spring-boot-starter-actuator/2.0.1.RELEASE/1ae431903895eabeccbdd611580ce63b374ccd1b/spring-boot-starter-actuator-2.0.1.RELEASE.jar:/Users/hfguan/.gradle/caches/modules-2/files-2.1/org.springframework.boot/spring-boot-starter-web/2.0.1.RELEASE/88751ed76791d12425ce5a80476baf1749a44cf4/spring-boot-starter-web-2.0.1.RELEASE.jar:/Users/hfguan/.gradle/caches/modules-2/files-2.1/org.mockito/mockito-all/1.10.19/539df70269cc254a58cccc5d8e43286b4a73bf30/mockito-all-1.10.19.jar:/Users/hfguan/.gradle/caches/modules-2/files-2.1/junit/junit/4.12/2973d150c0dc1fefe998f834810d68f278ea58ec/junit-4.12.jar:/Users/hfguan/.gradle/caches/modules-2/files-2.1/org.springframework.boot/spring-boot-starter-json/2.0.1.RELEASE/f2e1aeeb1ac02bfa1b4f7254633484af1866fc65/spring-boot-starter-json-2.0.1.RELEASE.jar:/Users/hfguan/.gradle/caches/modules-2/files-2.1/org.springframework.boot/spring-boot-starter/2.0.1.RELEASE/33abc1286b0aabea4f08ff4285d09e587835a716/spring-boot-starter-2.0.1.RELEASE.jar:/Users/hfguan/.gradle/caches/modules-2/files-2.1/org.springframework.boot/spring-boot-actuator-autoconfigure/2.0.1.RELEASE/794aa7d6b6e05563c69a4684d2f5b7c78e209b0a/spring-boot-actuator-autoconfigure-2.0.1.RELEASE.jar:/Users/hfguan/.gradle/caches/modules-2/files-2.1/io.micrometer/micrometer-core/1.0.3/8234fa7ea2b2d6f7147209dcaaa7cd347951d5eb/micrometer-core-1.0.3.jar:/Users/hfguan/.gradle/caches/modules-2/files-2.1/org.springframework.boot/spring-boot-starter-tomcat/2.0.1.RELEASE/4b46f4aaff6c8a5a1c8184996d5e9e8a9354db8d/spring-boot-starter-tomcat-2.0.1.RELEASE.jar:/Users/hfguan/.gradle/caches/modules-2/files-2.1/org.hibernate.validator/hibernate-validator/6.0.9.Final/b149e4cce82379f11f6129eb3187ca8ae5404005/hibernate-validator-6.0.9.Final.jar:/Users/hfguan/.gradle/caches/modules-2/files-2.1/org.springframework/spring-webmvc/5.0.5.RELEASE/a7fd53c7ad06b0fa7dd4ff347de1b2dc508739e/spring-webmvc-5.0.5.RELEASE.jar:/Users/hfguan/.gradle/caches/modules-2/files-2.1/org.springframework/spring-web/5.0.5.RELEASE/d51dbb5cabe72ae02e400577bac48f7fc94088de/spring-web-5.0.5.RELEASE.jar:/Users/hfguan/.gradle/caches/modules-2/files-2.1/org.hamcrest/hamcrest-core/1.3/42a25dc3219429f0e5d060061f71acb49bf010a0/hamcrest-core-1.3.jar:/Users/hfguan/.gradle/caches/modules-2/files-2.1/org.springframework.boot/spring-boot-autoconfigure/2.0.1.RELEASE/b0bf9d34ed70c6987a86cd58a009065e5fa02545/spring-boot-autoconfigure-2.0.1.RELEASE.jar:/Users/hfguan/.gradle/caches/modules-2/files-2.1/org.springframework.boot/spring-boot-actuator/2.0.1.RELEASE/aab310ca611fbdb3fe0f74f3f8644ee012abac8d/spring-boot-actuator-2.0.1.RELEASE.jar:/Users/hfguan/.gradle/caches/modules-2/files-2.1/org.springframework.boot/spring-boot/2.0.1.RELEASE/b8c5b14cbb0e52fdded8f98a8c1493cc74c7cf59/spring-boot-2.0.1.RELEASE.jar:/Users/hfguan/.gradle/caches/modules-2/files-2.1/org.springframework.boot/spring-boot-starter-logging/2.0.1.RELEASE/10681a28c95e9f9c0159327a1ed0c860517c7ad7/spring-boot-starter-logging-2.0.1.RELEASE.jar:/Users/hfguan/.gradle/caches/modules-2/files-2.1/javax.annotation/javax.annotation-api/1.3.2/934c04d3cfef185a8008e7bf34331b79730a9d43/javax.annotation-api-1.3.2.jar:/Users/hfguan/.gradle/caches/modules-2/files-2.1/org.springframework/spring-context/5.0.5.RELEASE/9cca4bf5acb693249a01c218f471c677b951d6e2/spring-context-5.0.5.RELEASE.jar:/Users/hfguan/.gradle/caches/modules-2/files-2.1/org.springframework/spring-aop/5.0.5.RELEASE/b11b61b94d7fb752a1c9bf3461d655c3084fae47/spring-aop-5.0.5.RELEASE.jar:/Users/hfguan/.gradle/caches/modules-2/files-2.1/org.springframework/spring-beans/5.0.5.RELEASE/984445863c0bbdaaf860615762d998b471a6bf92/spring-beans-5.0.5.RELEASE.jar:/Users/hfguan/.gradle/caches/modules-2/files-2.1/org.springframework/spring-expression/5.0.5.RELEASE/fc6c7a95aeb7d00f4c65c338b08d97767eb0dd99/spring-expression-5.0.5.RELEASE.jar:/Users/hfguan/.gradle/caches/modules-2/files-2.1/org.springframework/spring-core/5.0.5.RELEASE/1bd9feb1d9dac6accd27f5244b6c47cfcb55045c/spring-core-5.0.5.RELEASE.jar:/Users/hfguan/.gradle/caches/modules-2/files-2.1/org.yaml/snakeyaml/1.19/2d998d3d674b172a588e54ab619854d073f555b5/snakeyaml-1.19.jar:/Users/hfguan/.gradle/caches/modules-2/files-2.1/com.fasterxml.jackson.datatype/jackson-datatype-jsr310/2.9.5/d1f0d11e816bc04e222a261106ca138801841c2d/jackson-datatype-jsr310-2.9.5.jar:/Users/hfguan/.gradle/caches/modules-2/files-2.1/com.fasterxml.jackson.datatype/jackson-datatype-jdk8/2.9.5/23e37f085279ba316c0df923513b81609e1d1f6/jackson-datatype-jdk8-2.9.5.jar:/Users/hfguan/.gradle/caches/modules-2/files-2.1/com.fasterxml.jackson.module/jackson-module-parameter-names/2.9.5/f824c60751ffb7bfc3a0d30dfe0e42317d8e67f5/jackson-module-parameter-names-2.9.5.jar:/Users/hfguan/.gradle/caches/modules-2/files-2.1/com.fasterxml.jackson.core/jackson-databind/2.9.5/3490508379d065fe3fcb80042b62f630f7588606/jackson-databind-2.9.5.jar:/Users/hfguan/.gradle/caches/modules-2/files-2.1/org.hdrhistogram/HdrHistogram/2.1.10/9e1ac84eed220281841b75e72fb9de5a297fbf04/HdrHistogram-2.1.10.jar:/Users/hfguan/.gradle/caches/modules-2/files-2.1/org.latencyutils/LatencyUtils/2.0.3/769c0b82cb2421c8256300e907298a9410a2a3d3/LatencyUtils-2.0.3.jar:/Users/hfguan/.gradle/caches/modules-2/files-2.1/org.apache.tomcat.embed/tomcat-embed-websocket/8.5.29/37786f4ca8a1597a91a0f437e659a76d1fcc5bf1/tomcat-embed-websocket-8.5.29.jar:/Users/hfguan/.gradle/caches/modules-2/files-2.1/org.apache.tomcat.embed/tomcat-embed-core/8.5.29/51eac5adde4bc019261b787cb99e5548206908e6/tomcat-embed-core-8.5.29.jar:/Users/hfguan/.gradle/caches/modules-2/files-2.1/org.apache.tomcat.embed/tomcat-embed-el/8.5.29/893fb2c87ec1aa248a7911d76c0c06b3fca6bc9b/tomcat-embed-el-8.5.29.jar:/Users/hfguan/.gradle/caches/modules-2/files-2.1/javax.validation/validation-api/2.0.1.Final/cb855558e6271b1b32e716d24cb85c7f583ce09e/validation-api-2.0.1.Final.jar:/Users/hfguan/.gradle/caches/modules-2/files-2.1/org.jboss.logging/jboss-logging/3.3.2.Final/3789d00e859632e6c6206adc0c71625559e6e3b0/jboss-logging-3.3.2.Final.jar:/Users/hfguan/.gradle/caches/modules-2/files-2.1/com.fasterxml/classmate/1.3.4/3d5f48f10bbe4eb7bd862f10c0583be2e0053c6/classmate-1.3.4.jar:/Users/hfguan/.gradle/caches/modules-2/files-2.1/ch.qos.logback/logback-classic/1.2.3/7c4f3c474fb2c041d8028740440937705ebb473a/logback-classic-1.2.3.jar:/Users/hfguan/.gradle/caches/modules-2/files-2.1/org.apache.logging.log4j/log4j-to-slf4j/2.10.0/f7e631ccf49cfc0aefa4a2a728da7d374c05bd3c/log4j-to-slf4j-2.10.0.jar:/Users/hfguan/.gradle/caches/modules-2/files-2.1/org.slf4j/jul-to-slf4j/1.7.25/af5364cd6679bfffb114f0dec8a157aaa283b76/jul-to-slf4j-1.7.25.jar:/Users/hfguan/.gradle/caches/modules-2/files-2.1/org.springframework/spring-jcl/5.0.5.RELEASE/f4a2854b9d865e8b86717595aec16f877f8c6489/spring-jcl-5.0.5.RELEASE.jar:/Users/hfguan/.gradle/caches/modules-2/files-2.1/com.fasterxml.jackson.core/jackson-annotations/2.9.0/7c10d545325e3a6e72e06381afe469fd40eb701/jackson-annotations-2.9.0.jar:/Users/hfguan/.gradle/caches/modules-2/files-2.1/com.fasterxml.jackson.core/jackson-core/2.9.5/a22ac51016944b06fd9ffbc9541c6e7ce5eea117/jackson-core-2.9.5.jar:/Users/hfguan/.gradle/caches/modules-2/files-2.1/ch.qos.logback/logback-core/1.2.3/864344400c3d4d92dfeb0a305dc87d953677c03c/logback-core-1.2.3.jar:/Users/hfguan/.gradle/caches/modules-2/files-2.1/org.slf4j/slf4j-api/1.7.25/da76ca59f6a57ee3102f8f9bd9cee742973efa8a/slf4j-api-1.7.25.jar:/Users/hfguan/.gradle/caches/modules-2/files-2.1/org.apache.logging.log4j/log4j-api/2.10.0/fec5797a55b786184a537abd39c3fa1449d752d6/log4j-api-2.10.0.jar:/Users/hfguan/.gradle/caches/modules-2/files-2.1/org.apache.tomcat/tomcat-annotations-api/8.5.29/5505a72b5e7d6c2324d3f104cdd613a5770b4601/tomcat-annotations-api-8.5.29.jar" com.intellij.rt.execution.junit.JUnitStarter -ideVersion5 -junit4 com.test.blue.SayHelloServiceTest,should_throw_exception
java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at com.test.blue.SayHelloServiceTest.should_throw_exception(SayHelloServiceTest.java:46)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:47)
at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)
at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)
Caused by: java.lang.ArithmeticException: / by zero
at com.test.blue.SayHelloService.getNumber(SayHelloService.java:18)
... 27 more
Process finished with exit code 255
然后捕获异常，或者在注解上加@Test(expected=Exception.class)两种方法解决测试失败
1）利用junit的@Test(expected=Exception.class)
@Test(expected = Exception.class)
public void should_throw_exception() throws NoSuchMethodException, InvocationTargetException, IllegalAccessException {
SayHelloService sayHelloService = new SayHelloService();
Class<SayHelloService> classType = SayHelloService.class;
Method method = classType.getDeclaredMethod("getNumber", new Class[]{Integer.class});
method.setAccessible(true); // 抑制Java对修饰符的检查
method.invoke(sayHelloService, new Object[]{1});
}2）捕获异常
@Test
public void should_throw_exception() throws NoSuchMethodException, IllegalAccessException {
try {
SayHelloService sayHelloService = new SayHelloService();
Class<SayHelloService> classType = SayHelloService.class;
Method method = classType.getDeclaredMethod("getNumber", new Class[]{Integer.class});
method.setAccessible(true); // 抑制Java对修饰符的检查
method.invoke(sayHelloService, new Object[]{1});
} catch (InvocationTargetException e) {
System.out.println("此处接收被调用方法内部未被捕获的异常");
System.out.println(e.getTargetException().getMessage());
Assert.assertEquals("/ by zero", e.getTargetException().getMessage());
e.printStackTrace();
}
}案例三：
利用反射修改私有属性
@Test
public void should_modify_name_successfully() throws NoSuchFieldException, IllegalAccessException {
SayHelloService sayHelloService= new SayHelloService();
Class<SayHelloService> classType = SayHelloService.class;
Field field = classType.getDeclaredField("name");
field.setAccessible(true); // 抑制Java对修饰符的检查
field.set(sayHelloService, "hello world!");
Assert.assertEquals("hello world!",sayHelloService.getName());
}含有私有方法的类
package com.test.blue;
public class SayHelloService {
private String name = "Guanguan";
public String getName() {
return name;
}
private String sayHi() {
return "hello ,today is Wednesday!";
}
}