JMockit学习笔记

1 基本概念

1.1 常用注解

@Mocked：被修饰的对象将会被Mock，对应的类和实例都会受影响（同一个测试用例中）

@Injectable：仅Mock被修饰的对象

@Capturing：可以mock接口以及其所有的实现类

@Mock：MockUp模式中，指定被Fake的方法

1.2 常用的类

Expectations：期望，指定的方法必须被调用

StrictExpectations：严格的期望，指定方法必须按照顺序调用

NonStrictExpectations：非严格的期望，是否调用和顺序不作要求

Verifications：验证，一般配合NonStrictExpectations来使用

Invocation：工具类，可以获取调用信息

Delegate：自己指定返回值，适合那种需要参数决定返回值的场景，只需指定匿名子类就可以。

MockUp：模拟函数实现

Deencapsulation：反射工具类

2 使用实例

现有两个类如下：

SimpleTool.java:

public class SimpleTool {
public String fun1(String str) {
return "real: public String fun1(" + str + ")";
}

private String fun2(String str) {
return "real: private String fun2(" + str + ")";
}

public String fun3(String str) {
return "real: public String fun3(" + str + ")";
}

public String fun4(String str) {
return fun2(str);
}
}

UseSimpleTool.java:

public class UseSimpleTool {
public String fun1(String name) {
SimpleTool simpleTool = new SimpleTool();
return simpleTool.fun1(name);
}
}

2.1 Status-based

2.1.1 实例1:Mocked

@Mocked
SimpleTool simpleTool;

@Test
public void testExpectation() {

//未mock函数返回null
new Expectations() {
{
simpleTool.fun1(anyString);
result = "MOCK";
}
};

System.out.println(simpleTool.fun1("param"));
System.out.println(simpleTool.fun3("param"));
System.out.println(new UseSimpleTool().fun1("param"));

new Verifications() {
{
simpleTool.fun1(anyString);
times = 2;
}
};
}

输出：

MOCK

null

MOCK

2.1.2 实例2:Injectable

@Injectable
SimpleTool simpleTool;

@Test
public void testExpectation() {

//未mock函数返回null
new Expectations() {
{
simpleTool.fun1(anyString);
result = "MOCK";
}
};

System.out.println(simpleTool.fun1("param"));
System.out.println(simpleTool.fun3("param"));
System.out.println(new UseSimpleTool().fun1("param"));

new Verifications() {
{
simpleTool.fun1(anyString);
times = 1;
}
};
}

输出：

MOCK

null

real: public String fun1(param)

2.1.3 结果可变Delegate

@Mocked
SimpleTool simpleTool;

@Test
public void testExpectation() {

new Expectations() {
{
simpleTool.fun1(anyString);
result = new Delegate<String>() {
public String aDelegateMethod(String str) {
return str.equals("param0") ? "MOCK0" : "MOCK1";
}
};
}
};

System.out.println(simpleTool.fun1("param0"));
System.out.println(simpleTool.fun3("param"));
System.out.println(new UseSimpleTool().fun1("param1"));

new Verifications() {
{
simpleTool.fun1(anyString);
times = 2;
}
};
}

输出：

MOCK0

null

MOCK1

2.2 Behavior-based

2.2.1 Mock对象公有方法

@Test
public void testMockUp() {
//影响该类所有实例
new MockUp<SimpleTool>(){
//未mock函数不受影响
@Mock
public String fun1(String str) {
return "(MOCK)";
}
};

SimpleTool simpleTool = new SimpleTool();
System.out.println(simpleTool.fun1("param"));
System.out.println(simpleTool.fun3("param"));
UseSimpleTool useSimpleTool = new UseSimpleTool();
System.out.println(useSimpleTool.fun1("param"));
}

输出：

(MOCK)

real: public String fun3(param)

(MOCK)

2.2.2 Mock对象私有方法

@Test
public void testMockUp() {
new MockUp<SimpleTool>(){
//未mock函数不受影响
@Mock
private String fun2(String str) {
return "(MOCK)";
}
};

SimpleTool simpleTool = new SimpleTool();
System.out.println(simpleTool.fun1("param"));
System.out.println(simpleTool.fun3("param"));
System.out.println(simpleTool.fun4("param"));
}

输出：

real: public String fun1(param)

real: public String fun3(param)

(MOCK)

2.2.3 Mock接口

现有接口及其实现类如下：

SimleInterface.java:

public interface SimpleInterface {
String getCityName();
String getAreaName();
}

SimpleInterfaceImpl.java:

public class SimpleInterfaceImpl implements SimpleInterface {
public String getCityName() {
return "default city";
}
public String getAreaName() {
return "default area";
}
}

实例:

//此处使用Injectable和Mocked为一样的效果
@Injectable
SimpleInterface simpleInterface;

@Test
public void testUpper() throws Exception {
SimpleInterface mockInstance =  new MockUp<SimpleInterface>() {
@Mock
public String getCityName() {
return "BEIJING(MOCK)";
}

@Mock
public String getAreaName() {
return "HUABEI(MOCK)";
}

}.getMockInstance();

System.out.println(mockInstance.getCityName());
System.out.println(mockInstance.getAreaName());
System.out.println(simpleInterface.getCityName());
System.out.println(simpleInterface.getAreaName());
SimpleInterfaceImpl simpleInterfaceImpl = new SimpleInterfaceImpl();
System.out.println(simpleInterfaceImpl.getCityName());
System.out.println(simpleInterfaceImpl.getAreaName());
}

输出：

BEIJING(MOCK)

HUABEI(MOCK)

null

null

default city

default area

对于接口的Mock如何影响实现该接口的所有类的对象，尚需进一步研究。