运行Android工具测试时出现错误“未找到测试”

我是测试的初学者。我为android studio中的登录活动创建了一个简单的测试用例。但是我遇到了一个错误，但无法解决。这是我的测试代码。帮助将不胜感激。

package com.example.hassidiczaddic.testinglist;

import android.app.Application;
import android.support.test.rule.ActivityTestRule;
import android.support.test.runner.AndroidJUnit4;
import android.test.ActivityInstrumentationTestCase2;
import android.test.ApplicationTestCase;
import android.test.suitebuilder.annotation.LargeTest;

import org.junit.Before;
import org.junit.Rule;
import org.junit.Test;
import org.junit.runner.RunWith;

import static android.support.test.espresso.Espresso.onView;
import static android.support.test.espresso.action.ViewActions.click;
import static android.support.test.espresso.action.ViewActions.closeSoftKeyboard;
import static android.support.test.espresso.action.ViewActions.typeText;
import static android.support.test.espresso.assertion.ViewAssertions.matches;
import static android.support.test.espresso.matcher.ViewMatchers.withId;
import static android.support.test.espresso.matcher.ViewMatchers.withText;

@RunWith(AndroidJUnit4.class)
@LargeTest
public class ApplicationTest {

    public static final String STRING_TO_BE_TYPED = "Wolfmatrix";

    @Rule
    public ActivityTestRule<MainActivity> mActivityRule = new ActivityTestRule<>(MainActivity.class);

    @Test
    public void LoginActivity() {
        onView(withId(R.id.etFName))
                .perform(typeText(STRING_TO_BE_TYPED), closeSoftKeyboard());
        onView(withId(R.id.etLName))
                .perform(typeText(STRING_TO_BE_TYPED), closeSoftKeyboard());
        onView(withId(R.id.btnSubmit))
            .perform(click());
        onView(withId(R.id.tvView))
            .check(matches(withText(STRING_TO_BE_TYPED)));
    }

}

这是我的错误：

Running tests

$ adb shell am instrument -w -r   -e debug false -e class       
com.example.hassidiczaddic.testinglist.ApplicationTest
com.example.hassidiczaddic.testinglist.
test/android.test.InstrumentationTestRunner
Client not ready yet..Test running started
junit.framework.AssertionFailedError: No tests found in     
com.example.hassidiczaddic.testinglist.ApplicationTest
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:1619)
Tests ran to completion.

这是我的gradle文件：

apply plugin: 'com.android.application'

android {
    compileSdkVersion 23
    buildToolsVersion "23.0.3"

    defaultConfig {
        applicationId "com.example.hassidiczaddic.testinglist"
        minSdkVersion 16
        targetSdkVersion 23
        versionCode 1
        versionName "1.0"
    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'),'proguard-rules.pro'
        }
    }

    dependencies {
        compile fileTree(dir: 'libs', include: ['*.jar'])
        testCompile 'junit:junit:4.12'
        compile 'com.android.support:appcompat-v7:23.0.1'
        // App dependencies
        compile 'com.android.support:support-annotations:23.0.1'
        compile 'com.google.guava:guava:18.0'
        androidTestCompile 'com.android.support:support-annotations:23.0.1'
        androidTestCompile 'com.android.support.test:runner:0.4.1'
        androidTestCompile 'com.android.support.test:rules:0.4.1'
        androidTestCompile 'com.android.support.test.espresso:espresso-core:2.2.1'
    }
}