麻烦大神帮我看看，在 pc 连接真机执行时，报 no tests were found. 我的安卓手机版本为 7.1.
Running tests
Test running startedTest running failed: No test results
Empty test suite.
Gradle 配置：
apply plugin: 'com.android.application'

android {
compileSdkVersion 21
buildToolsVersion "21.1.2"

defaultConfig {
applicationId "com.pingan.myapp1"
minSdkVersion 18
targetSdkVersion 28
versionCode 1
versionName "1.0"

testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
}
buildTypes {
release {
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
}
}
}
dependencies {
compile fileTree(include: ['*.jar'], dir: 'libs')
compile 'com.android.support:appcompat-v7:21.+'
compile files('libs/espresso-contrib-2.2-release-no-dep.jar')
compile files('libs/espresso-core-2.2-release-no-dep.jar')
compile files('libs/espresso-idling-resource-2.2-release-no-dep.jar')
compile files('libs/espresso-intents-2.2-release-no-dep.jar')
compile files('libs/espresso-web-2.2-release-no-dep.jar')
compile files('libs/exposed-instrumentation-api-publish-0.3-release-no-dep.jar')
compile files('libs/guava-18.0.jar')
compile files('libs/hamcrest-core-1.3.jar')
compile files('libs/hamcrest-integration-1.3.jar')
compile files('libs/hamcrest-library-1.3.jar')
compile files('libs/javawriter-2.1.1.jar')
compile files('libs/javax.annotation-api-1.2.jar')
compile files('libs/javax.inject-1.jar')
compile files('libs/jsr305-2.0.1.jar')
compile files('libs/junit-4.12.jar')
compile files('libs/rules-0.3-release-no-dep.jar')
compile files('libs/runner-0.3-release-no-dep.jar')
compile files('libs/uiautomator-v18-2.1.1-release-no-dep.jar')
}
测试代码：
package com.pingan.myapp1;

+import android.app.Instrumentation;

/**

• Created by Administrator on 2018/7/3.
  */
  @RunWith(AndroidJUnit4.class)
  public class PinganAppTest {
  private static Instrumentation mInstrumentation;
  private UiDevice mDevice;
  String toastMessage;
  Long toastOccurTime;
  private final int LAUNCH_TIMEOUT = 5000;

  @Before
  public void setUp() {
  mInstrumentation = InstrumentationRegistry.getInstrumentation();
  mDevice = UiDevice.getInstance(mInstrumentation);
  initToastListener();
  }
  private static void initToastListener() {

  mInstrumentation.getUiAutomation().setOnAccessibilityEventListener(new UiAutomation.OnAccessibilityEventListener() {
  @Override
  public void onAccessibilityEvent(AccessibilityEvent event) {
  Log.i("AAA", "onAccessibilityEvent: " + event.toString());
  //判断是否是通知事件
  if (event.getEventType() != AccessibilityEvent.TYPE_NOTIFICATION_STATE_CHANGED) {
  return;
  }
  //获取消息来源
  String sourcePackageName = (String) event.getPackageName();
  //获取事件具体信息
  Parcelable parcelable = event.getParcelableData();
  //如果不是下拉通知栏消息，则为其它通知信息，包括 Toast
  if (!(parcelable instanceof Notification)) {
  Log.i("AAA",event.getText().toString());
  String toastMessage = (String) event.getText().get(0);
  Long toastOccurTime = event.getEventTime();
  Log.i("AAA", "Latest Toast Message: " + toastMessage + " [Time: " + toastOccurTime + ", Source: " + sourcePackageName + "]");
  }else {
  Log.i("AAA",event.getParcelableData().toString());
  }
  }
  });
  }

  @Test
  public void testLoginFailed() {
  UiObject2 username = mDevice.wait(Until.findObject(By.depth(18).clazz(TextView.class)), LAUNCH_TIMEOUT);
  username.clear();
  username.setText("15888888881");
  UiObject2 password = mDevice.wait(Until.findObject(By.depth(18).text("请输入您的密码")), LAUNCH_TIMEOUT);
  password.clear();
  password.setText("paic@1234");
  UiObject2 smscode = mDevice.wait(Until.findObject(By.depth(19).clazz(TextView.class)), LAUNCH_TIMEOUT);
  smscode.clear();
  smscode.setText("111111");
  UiObject2 loginButton = mDevice.findObject(By.desc("登录"));
  loginButton.click();
  // Verify the test is displayed in the Ui
  final long startTimeMillis = SystemClock.uptimeMillis();
  boolean isSuccessfulCatchToast;
  while (true) {
  long currentTimeMillis = SystemClock.uptimeMillis();
  long elapsedTimeMillis = currentTimeMillis - startTimeMillis;
  if (elapsedTimeMillis > 5000L) {
  Log.i("AAA", "超过 5s 未能捕获到预期 Toast!");
  isSuccessfulCatchToast = false;
  break;
  }
  if (toastOccurTime > startTimeMillis) {

  isSuccessfulCatchToast = "验证码错误".equals(toastMessage);
  break;
  }
  }
  Assert.assertTrue("捕获预期 Toast 失败!", isSuccessfulCatchToast);
  }}