如何使用Mock修改Android设备上的features

背景

手工测试过程中有个测试场景需要删除测试设备上某个Android feature，往上搜索了一圈没找到有效的操作方法。获取Android设备所有的feature可以通过adb命令pm list features或者Android代码Context.getPackageManager().getSystemAvailableFeatures()，但都没有对应的修改方法。

既然feature是从Context获取的，那能不能构造一个只包含我想要的feature的Context呢。顺着这个思路，有了下面的方案。

方案设计

单元测试常用的Mock技术，就是来构造假/模拟对象的。但如果完全构造，又担心和真实环境差别较大，测试结果不可靠。能不能从真实Android设备中获取真实的Context，把不想要的feature去除，再给到被测试方法中呢？

答案是肯定的，通过选用流行的Mock组件Mockito ，官网上给出了下面2种Mock Java对象的方式：

1. mock()/@Mock: create mock
2. spy()/@Spy: partial mocking, real methods are invoked but still can be verified and stubbed

可以看到Spy这种Mock方式可完美地解决我的需求。

实现（简化版需求）

业务需求说明

获取所有Android Features并把feature name打印在日志中，使用adb命令的效果如下：

  study git:(master)  adb shell pm list features                                    
feature:reqGlEsVersion=0x30002
feature:android.hardware.audio.output
feature:android.hardware.bluetooth
feature:android.hardware.bluetooth_le
feature:android.hardware.camera
feature:android.hardware.camera.any
feature:android.hardware.camera.autofocus
feature:android.hardware.camera.capability.manual_post_processing
feature:android.hardware.camera.capability.manual_sensor
feature:android.hardware.camera.capability.raw
feature:android.hardware.camera.flash
feature:android.hardware.camera.front
feature:android.hardware.camera.level.full
feature:android.hardware.faketouch
feature:android.hardware.location
feature:android.hardware.location.gps
feature:android.hardware.location.network
feature:android.hardware.microphone
feature:android.hardware.nfc.any
feature:android.hardware.opengles.aep
feature:android.hardware.ram.normal
feature:android.hardware.screen.landscape
feature:android.hardware.screen.portrait
feature:android.hardware.sensor.accelerometer
feature:android.hardware.sensor.compass
feature:android.hardware.sensor.light
feature:android.hardware.sensor.proximity
feature:android.hardware.sensor.stepcounter
feature:android.hardware.telephony
feature:android.hardware.telephony.cdma
feature:android.hardware.telephony.gsm
feature:android.hardware.touchscreen
feature:android.hardware.touchscreen.multitouch
feature:android.hardware.touchscreen.multitouch.distinct
feature:android.hardware.touchscreen.multitouch.jazzhand
feature:android.hardware.usb.accessory
feature:android.hardware.usb.host
feature:android.hardware.vulkan.compute
feature:android.hardware.vulkan.level
feature:android.hardware.vulkan.version=4194307
feature:android.hardware.wifi
feature:android.hardware.wifi.direct
feature:android.software.activities_on_secondary_displays
feature:android.software.app_widgets
feature:android.software.autofill
feature:android.software.backup
feature:android.software.companion_device_setup
feature:android.software.connectionservice
feature:android.software.cts
feature:android.software.device_admin
feature:android.software.file_based_encryption
feature:android.software.input_methods
feature:android.software.live_wallpaper
feature:android.software.managed_users
feature:android.software.midi
feature:android.software.picture_in_picture
feature:android.software.print
feature:android.software.securely_removes_users
feature:android.software.sip
feature:android.software.sip.voip
feature:android.software.verified_boot
feature:android.software.voice_recognizers
feature:android.software.webview

业务需求代码实现

public class FeaturesUtil {
    private static final String TAG = "FeaturesUtil";

    public static void getFeatures(Context context) {
        PackageManager packageManager = context.getPackageManager();
        FeatureInfo[] featureInfos = packageManager.getSystemAvailableFeatures();

        for (FeatureInfo featureInfo : featureInfos) {
            Log.i(TAG, "feature: " + featureInfo.name);
        }
    }
}

测试代码实现(去除bluetooth feature)

    @Spy
    Context context = InstrumentationRegistry.getInstrumentation().getTargetContext();;

    @Spy
    PackageManager packageManager = context.getPackageManager();

		@Test
    public void getFeatures() {
        // 去除bluetooth feature
        FeatureInfo[] mockedFeatureInfos = removeFeature(packageManager.getSystemAvailableFeatures(),
                Arrays.asList("android.hardware.bluetooth", "android.hardware.bluetooth_le"));

        when(packageManager.getSystemAvailableFeatures()).thenReturn(mockedFeatureInfos);
        when(context.getPackageManager()).thenReturn(packageManager);

        FeaturesUtil.getFeatures(context);
    }

    /**
     * 根据feature name删除一个或多个feature
     *
     * @param featureInfos FeatureInfo数组
     * @param featureNames 字符串列表，每个元素是要删除的FeatureInfo的name
     * @return 删除之后的FeatureInfo数组
     */
    private FeatureInfo[] removeFeature(FeatureInfo[] featureInfos, List<String> featureNames) {
        List<FeatureInfo> featureInfoList = new ArrayList();

        for (FeatureInfo featureInfo :
             featureInfos) {
            if (featureInfo.name != null && !(featureNames.contains(featureInfo.name))) {
                featureInfoList.add(featureInfo);
            }
        }

        return featureInfoList.toArray(new FeatureInfo[featureInfoList.size()]);
    }

运行测试代码后Logcat输出

可以看到bluetooth相关的feature已经没有了

2021-04-07 13:23:39.266 16238-16268/? I/FeaturesUtil: feature: android.hardware.sensor.proximity

2021-04-07 13:23:39.266 16238-16268/? I/FeaturesUtil: feature: android.hardware.sensor.accelerometer

2021-04-07 13:23:39.266 16238-16268/? I/FeaturesUtil: feature: android.hardware.faketouch

2021-04-07 13:23:39.266 16238-16268/? I/FeaturesUtil: feature: android.hardware.usb.accessory

2021-04-07 13:23:39.266 16238-16268/? I/FeaturesUtil: feature: android.hardware.telephony.cdma

2021-04-07 13:23:39.266 16238-16268/? I/FeaturesUtil: feature: android.software.backup

2021-04-07 13:23:39.266 16238-16268/? I/FeaturesUtil: feature: android.hardware.touchscreen

2021-04-07 13:23:39.266 16238-16268/? I/FeaturesUtil: feature: android.hardware.touchscreen.multitouch

2021-04-07 13:23:39.266 16238-16268/? I/FeaturesUtil: feature: android.software.print

2021-04-07 13:23:39.266 16238-16268/? I/FeaturesUtil: feature: android.software.activities_on_secondary_displays

2021-04-07 13:23:39.266 16238-16268/? I/FeaturesUtil: feature: android.software.voice_recognizers

2021-04-07 13:23:39.266 16238-16268/? I/FeaturesUtil: feature: android.software.picture_in_picture

2021-04-07 13:23:39.266 16238-16268/? I/FeaturesUtil: feature: android.hardware.opengles.aep

2021-04-07 13:23:39.266 16238-16268/? I/FeaturesUtil: feature: android.hardware.camera.autofocus

2021-04-07 13:23:39.266 16238-16268/? I/FeaturesUtil: feature: android.hardware.telephony.gsm

2021-04-07 13:23:39.266 16238-16268/? I/FeaturesUtil: feature: android.software.sip.voip

2021-04-07 13:23:39.266 16238-16268/? I/FeaturesUtil: feature: android.hardware.usb.host

2021-04-07 13:23:39.266 16238-16268/? I/FeaturesUtil: feature: android.hardware.audio.output

2021-04-07 13:23:39.266 16238-16268/? I/FeaturesUtil: feature: android.software.verified_boot

2021-04-07 13:23:39.266 16238-16268/? I/FeaturesUtil: feature: android.hardware.camera.flash

2021-04-07 13:23:39.266 16238-16268/? I/FeaturesUtil: feature: android.hardware.camera.front

2021-04-07 13:23:39.266 16238-16268/? I/FeaturesUtil: feature: android.hardware.screen.portrait

2021-04-07 13:23:39.266 16238-16268/? I/FeaturesUtil: feature: android.hardware.microphone

2021-04-07 13:23:39.266 16238-16268/? I/FeaturesUtil: feature: android.software.autofill

2021-04-07 13:23:39.266 16238-16268/? I/FeaturesUtil: feature: android.software.securely_removes_users

2021-04-07 13:23:39.266 16238-16268/? I/FeaturesUtil: feature: android.hardware.sensor.compass

2021-04-07 13:23:39.266 16238-16268/? I/FeaturesUtil: feature: android.hardware.touchscreen.multitouch.jazzhand

2021-04-07 13:23:39.266 16238-16268/? I/FeaturesUtil: feature: android.software.app_widgets

2021-04-07 13:23:39.266 16238-16268/? I/FeaturesUtil: feature: android.software.input_methods

2021-04-07 13:23:39.267 16238-16268/? I/FeaturesUtil: feature: android.hardware.sensor.light

2021-04-07 13:23:39.267 16238-16268/? I/FeaturesUtil: feature: android.hardware.vulkan.version

2021-04-07 13:23:39.267 16238-16268/? I/FeaturesUtil: feature: android.software.companion_device_setup

2021-04-07 13:23:39.267 16238-16268/? I/FeaturesUtil: feature: android.software.device_admin

2021-04-07 13:23:39.267 16238-16268/? I/FeaturesUtil: feature: android.hardware.camera

2021-04-07 13:23:39.267 16238-16268/? I/FeaturesUtil: feature: android.hardware.screen.landscape

2021-04-07 13:23:39.267 16238-16268/? I/FeaturesUtil: feature: android.hardware.ram.normal

2021-04-07 13:23:39.267 16238-16268/? I/FeaturesUtil: feature: android.software.managed_users

2021-04-07 13:23:39.267 16238-16268/? I/FeaturesUtil: feature: android.software.webview

2021-04-07 13:23:39.267 16238-16268/? I/FeaturesUtil: feature: android.hardware.sensor.stepcounter

2021-04-07 13:23:39.267 16238-16268/? I/FeaturesUtil: feature: android.hardware.camera.capability.manual_post_processing

2021-04-07 13:23:39.267 16238-16268/? I/FeaturesUtil: feature: android.hardware.camera.any

2021-04-07 13:23:39.267 16238-16268/? I/FeaturesUtil: feature: android.hardware.camera.capability.raw

2021-04-07 13:23:39.267 16238-16268/? I/FeaturesUtil: feature: android.hardware.vulkan.compute

2021-04-07 13:23:39.267 16238-16268/? I/FeaturesUtil: feature: android.software.connectionservice

2021-04-07 13:23:39.267 16238-16268/? I/FeaturesUtil: feature: android.hardware.touchscreen.multitouch.distinct

2021-04-07 13:23:39.267 16238-16268/? I/FeaturesUtil: feature: android.hardware.location.network

2021-04-07 13:23:39.267 16238-16268/? I/FeaturesUtil: feature: android.software.cts

2021-04-07 13:23:39.267 16238-16268/? I/FeaturesUtil: feature: android.software.sip

2021-04-07 13:23:39.267 16238-16268/? I/FeaturesUtil: feature: android.hardware.camera.capability.manual_sensor

2021-04-07 13:23:39.267 16238-16268/? I/FeaturesUtil: feature: android.hardware.camera.level.full

2021-04-07 13:23:39.267 16238-16268/? I/FeaturesUtil: feature: android.hardware.wifi.direct

2021-04-07 13:23:39.267 16238-16268/? I/FeaturesUtil: feature: android.software.live_wallpaper

2021-04-07 13:23:39.267 16238-16268/? I/FeaturesUtil: feature: android.hardware.location.gps

2021-04-07 13:23:39.267 16238-16268/? I/FeaturesUtil: feature: android.software.midi

2021-04-07 13:23:39.267 16238-16268/? I/FeaturesUtil: feature: android.hardware.nfc.any

2021-04-07 13:23:39.268 16238-16268/? I/FeaturesUtil: feature: android.hardware.wifi

2021-04-07 13:23:39.268 16238-16268/? I/FeaturesUtil: feature: android.hardware.location

2021-04-07 13:23:39.268 16238-16268/? I/FeaturesUtil: feature: android.hardware.vulkan.level

2021-04-07 13:23:39.268 16238-16268/? I/FeaturesUtil: feature: android.hardware.telephony

2021-04-07 13:23:39.268 16238-16268/? I/FeaturesUtil: feature: android.software.file_based_encryption

2021-04-07 13:23:39.269 16238-16268/? I/TestRunner: finished: getFeatures(com.aniu.featuresmock.FeaturesUtilTest)

总结

• 不直接使用Mock，而是使用Spy，最大限度保持测试环境真实可靠，从而保证测试效果
• 测试代码不要放在test目录，要放在androidTest目录，保证在真实设备上跑（不然代码也会报错）。目录结构如下：

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