java.lang.RuntimeException: Exception during suite construction

使用Android studio1.1版，进行单元测试，发生了异常，如下：

Running tests

Test running started
java.lang.RuntimeException: Exception during suite construction
at android.test.suitebuilder.TestSuiteBuilder$FailedToCreateTests.testSuiteConstructionFailed(TestSuiteBuilder.java:238)
at java.lang.reflect.Method.invokeNative(Native Method)
at android.test.AndroidTestRunner.runTest(AndroidTestRunner.java:190)
at android.test.AndroidTestRunner.runTest(AndroidTestRunner.java:175)
at android.test.InstrumentationTestRunner.onStart(InstrumentationTestRunner.java:555)
at android.app.Instrumentation$InstrumentationThread.run(Instrumentation.java:1732)
Caused by: java.lang.NullPointerException
at android.test.suitebuilder.TestMethod.<init>(TestMethod.java:47)
at android.test.suitebuilder.TestSuiteBuilder.build(TestSuiteBuilder.java:189)
at android.test.InstrumentationTestRunner.onCreate(InstrumentationTestRunner.java:379)
at android.app.ActivityThread.handleBindApplication(ActivityThread.java:4631)
at android.app.ActivityThread.access$1300(ActivityThread.java:165)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1433)
at android.os.Handler.dispatchMessage(Handler.java:107)
at android.os.Looper.loop(Looper.java:194)
at android.app.ActivityThread.main(ActivityThread.java:5391)
at java.lang.reflect.Method.invokeNative(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:833)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600)
at dalvik.system.NativeStart.main(Native Method)

Finish

解决办法：最后发现，必须是无参构造方法

public MyFirstTestActivityTest(Class activityClass) {
        super(activityClass); //不能用编辑器自动生成的参数(会报空指针异常)，只能自己传对象，如MainActivity.class
    }