android 自动化测试：不借助电脑，在设备上直接运行测试

package com.wispeedio.espressofirst;

import android.content.ComponentName;
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.EditText;

public class MainActivity extends AppCompatActivity {
    EditText editText;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        editText = (EditText) findViewById(R.id.inputField);
    }

    public void onClick(View view) {
        switch (view.getId()) {
            case R.id.changeText:
                editText.setText("Lalala");
                break;
            case R.id.switchActivity:
                Intent intent = new Intent(this, SecondActivity.class);
                intent.putExtra("input", editText.getText().toString());
                startActivity(intent);
                break;
            case R.id.run_test:
                // 方法1，使用 startInstrumentation 来启动 Test
                Bundle bd = new Bundle();
                // 指定执行特定类中的用例
                //bd.putString("class", "com.wispeedio.espressofirst.MainActivityEspressoTest");

                // bd 即使是空洞Bundle，也必须指定，
                // 否则报错：NullPointerException in onCreate() of AndroidJUnitRunner
                startInstrumentation(
                  new ComponentName(
                    "com.wispeedio.espressofirst.test",
                    "android.support.test.runner.AndroidJUnitRunner"), null, bd);

                // 方法2，可能有用，也可能因为权限不够而失败
                // 可以尝试添加 permission："android.permission.INJECT_EVENTS"
//                try {
//                    Process process =
//                      Runtime.getRuntime().exec(
//                        "adb shell am instrument -w com.wispeedio.espressofirst.test/android.support.test.runner.AndroidJUnitRunner");
//                } catch(Exception e) {
//                    Log.d("wiii", "am instrument error: " + e);
//                }
                break;
        }

    }
}

package com.wispeedio.espressofirst;

/**
 * Created by wi on 2018/1/5.
 */

import android.support.test.rule.ActivityTestRule;
import android.support.test.runner.AndroidJUnit4;
import android.util.Log;

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)
public class MainActivityEspressoTest {


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

    @Test
    public void ensureTextChangesWork() {
        // Type text and then press the button.
        onView(withId(R.id.inputField))
                .perform(typeText("HELLO"), closeSoftKeyboard());
        onView(withId(R.id.changeText)).perform(click());

        // Check that the text was changed.
        onView(withId(R.id.inputField)).check(matches(withText("Lalala")));
    }

    @Test
    public void changeText_newActivity() {
        // Type text and then press the button.
        onView(withId(R.id.inputField)).perform(typeText("NewText"),
                closeSoftKeyboard());
        onView(withId(R.id.switchActivity)).perform(click());

        // This view is in a different Activity, no need to tell Espresso.
        onView(withId(R.id.resultView)).check(matches(withText("NewText")));
    }
}