How to Mock static method in System Class or Third party Class

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Thank you for reading!

I want to Mock static method in System Class such as Math.java.

I have consulted the official MockStaticCases.java and code

public void testTestM10() throws Exception { System.out.println(Math.sin(60) < (-0.4)); mockStatic(Math.class); doReturn(-0.8).when(Math.sin(60)); assertTrue(Math.sin(60) < (-0.4)); verifyStatic(EmployeeService.class); Math.sin(60); }

it show me the following content in the console:

org.mockito.exceptions.misusing.UnfinishedStubbingException:
Unfinished stubbing detected here:
-> at com.zhangxing.mybatis.pojo.EmployeeServiceTest.testTestM10(EmployeeServiceTest.java:112)

E.g. thenReturn() may be missing.
Examples of correct stubbing:
when(mock.isOk()).thenReturn(true);
when(mock.isOk()).thenThrow(exception);
doThrow(exception).when(mock).someVoidMethod();
Hints:

1. missing thenReturn()

2. you are trying to stub a final method, which is not supported
   3: you are stubbing the behaviour of another mock inside before 'thenReturn' instruction is completed

   at com.zhangxing.mybatis.pojo.EmployeeServiceTest.testTestM10(EmployeeServiceTest.java:112)
   at org.junit.internal.runners.TestMethod.invoke(TestMethod.java:68)
   at org.junit.internal.runners.MethodRoadie$2.run(MethodRoadie.java:89)
   at org.junit.internal.runners.MethodRoadie.runBeforesThenTestThenAfters(MethodRoadie.java:97)
   at org.junit.internal.runners.MethodRoadie.runTest(MethodRoadie.java:87)
   at org.junit.internal.runners.MethodRoadie.run(MethodRoadie.java:50)
   at org.junit.internal.runners.ClassRoadie.runUnprotected(ClassRoadie.java:34)
   at org.junit.internal.runners.ClassRoadie.runProtected(ClassRoadie.java:44)
   at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
   at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:69)
   at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33)
   at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:235)
   at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:54)

Looking forward to your reply