Unit Test相关问题汇总

1、测试私有方法
（1）使用反射

public class Calcutate {

    public int test() {
        return add(2, 3);
    }

    private int add(int a, int b) {
        return a + b;
    }
}

public class CalcutateTest {
    @Test
    public void testAdd() {
        Calcutate cal = new Calcutate();
        Object result = null;
        try {
            Method method = cal.getClass().getDeclaredMethod("add",
                    new Class[] { int.class, int.class });// 获得method.注意,这里不能使用getMethod方法,因为这个方法只能获取public修饰的方法..
            method.setAccessible(true);// 这个设置为true.可以无视java的封装..不设置这个也无法或者这个Method
            result = method.invoke(cal, new Object[] { 2, 10 });

        } catch (Exception e) {
            e.printStackTrace();
        }
        Assert.assertEquals("Must equals.", 13, result);// 这里自定拆箱..
    }
}

method.setAccessible(true);

如果不显示设为true，则报错：

java.lang.IllegalAccessException: Class CalcutateTest can not access a member of class Calcutate with modifiers "private"
    at sun.reflect.Reflection.ensureMemberAccess(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at com.test.junit.CalcutateTest.testAdd(CalcutateTest.java:17)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:47)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:44)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:271)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:70)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:50)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:238)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:63)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:236)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:53)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:229)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:309)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)