Question

我无法弄清楚为什么我的仪器单元测试在下面的第一个代码块中指示的位置失败。据我所知，我已经在线跟踪了使用Room Persistence库的演示案例，并基于android开发人员网站进行了测试。被测试的代码是从Google“有风景的房间”代码实验室衍生而来的。该测试将插入一个对象并读取包装为LiveData的那些对象的列表。刚插入的对象应该在返回的列表中，但是LiveData返回null。

测试案例：

@RunWith(AndroidJUnit4.class)
public class PersonReadWriteTest
{
private PersonDAO personDao;
private EventDatabase database;

@Before
public void createDb ()
{
    Context appContext = InstrumentationRegistry.getTargetContext();
    database = Room.inMemoryDatabaseBuilder(appContext, EventDatabase.class).build();
    personDao = database.personDAO();
}

@After
public void closeDb () throws IOException
{
    database.close();
}

@Test
public void writePersonAndReadInList() throws Exception
{
    Person person = TestUtil.createPerson("John", "Doe");
    personDao.insert(person);
    LiveData<List<Person>> peopleLive = personDao.getAll();
    List<Person> people = peopleLive.getValue();
    assertNotNull(people); <=============================== FAILS HERE
    assertThat(people.size(), equalTo(1));
    Person read = people.get(0);
    assertNotNull(read);
    assertThat(read, equalTo(person));
}
}

测试结果：

java.lang.AssertionError
at org.junit.Assert.fail(Assert.java:86)
at org.junit.Assert.assertTrue(Assert.java:41)
at org.junit.Assert.assertNotNull(Assert.java:712)
at org.junit.Assert.assertNotNull(Assert.java:722)
at PersonReadWriteTest.writePersonAndReadInList(PersonReadWriteTest.java:69)
at java.lang.reflect.Method.invoke(Native Method)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
at android.support.test.internal.runner.junit4.statement.RunBefores.evaluate(RunBefores.java:80)
at android.support.test.internal.runner.junit4.statement.RunAfters.evaluate(RunAfters.java:61)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
at android.support.test.runner.AndroidJUnit4.run(AndroidJUnit4.java:101)
at org.junit.runners.Suite.runChild(Suite.java:128)
at org.junit.runners.Suite.runChild(Suite.java:27)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
at org.junit.runner.JUnitCore.run(JUnitCore.java:115)
at android.support.test.internal.runner.TestExecutor.execute(TestExecutor.java:56)
at android.support.test.runner.AndroidJUnitRunner.onStart(AndroidJUnitRunner.java:384)
at android.app.Instrumentation$InstrumentationThread.run(Instrumentation.java:2106)

人员实体：

@Entity(tableName="people")
public class Person implements Serializable
{
// ---------------------------------------------------------------
// Attributes

@PrimaryKey
private Long id = null;
@ColumnInfo(name="first_name")
private String firstName = null;
@ColumnInfo(name="last_name")
private String surname = null;
@ColumnInfo(name="address")
private String address = null;
@ColumnInfo(name="phone1")
private String phone1 = null;
@ColumnInfo(name="phone2")
private String phone2 = null;
@ColumnInfo(name="email")
private String email = null;

// ---------------------------------------------------------------
// Attribute access

... all the public getters and setters...

// -----------------------------------------------------------------

public Person ()
{}
}

DAO：

@Dao
public interface PersonDAO
{
@Query("SELECT * FROM people")
LiveData<List<Person>> getAll ();

@Query("SELECT * FROM people WHERE id IN (:ids)")
LiveData<List<Person>> loadAllByIds (int[] ids);

@Query("SELECT * FROM people WHERE first_name LIKE :first AND last_name LIKE :last LIMIT 1")
LiveData<Person> findByName (String first, String last);

@Insert(onConflict = OnConflictStrategy.REPLACE)
void insert (Person person);

@Delete
void delete (Person person);

@Query("DELETE from people")
void deleteAll ();
}

数据库类：

@Database(entities = { Event.class, Person.class }, version = 1)
public abstract class EventDatabase extends RoomDatabase
{
public abstract EventDAO eventDAO ();
public abstract PersonDAO personDAO ();

private static volatile EventDatabase INSTANCE;

static EventDatabase getDatabase (final Context context)
{
    if (INSTANCE == null)
    {
        synchronized (EventDatabase.class)
        {
            if (INSTANCE == null)
            {
                INSTANCE = Room.databaseBuilder(context.getApplicationContext(),
                        EventDatabase.class, "event_database").
                        allowMainThreadQueries(). // SHOULD NOT BE USED IN PRODUCTION !!!
                        addCallback(sRoomDatabaseCallback).build();
            }
        }
    }
    return INSTANCE;
}

private static RoomDatabase.Callback sRoomDatabaseCallback = new RoomDatabase.Callback() {
    @Override
    public void onOpen (@NonNull SupportSQLiteDatabase db)
    {
        super.onOpen(db);
        new PopulateDbAsync(INSTANCE).execute();
    }
};

private static class PopulateDbAsync extends AsyncTask<Void, Void, Void>
{
    private final EventDAO m_EventDao;
    private final PersonDAO m_PersonDao;

    PopulateDbAsync (EventDatabase db)
    {
        m_EventDao = db.eventDAO();
        m_PersonDao = db.personDAO();
    }

    @Override
    protected Void doInBackground (final Void... params)
    {
        Event event;
        m_EventDao.deleteAll();
        m_PersonDao.deleteAll();

        ... insert objects ...
        For example:
        Person person = new Person("Joe", "Bloe");
        m_PersonDao.insert(person);

        return null;
    }
}

}

从应用gradle文件中提取依赖项：

testImplementation 'junit:junit:4.12'
androidTestImplementation 'com.android.support:support-annotations:27.1.1'
androidTestImplementation 'com.android.support.test:runner:1.0.2'
androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'

// Lifecycle components
def archLifecycleVersion = "1.1.0"
implementation "android.arch.lifecycle:extensions:$archLifecycleVersion"
annotationProcessor "android.arch.lifecycle:compiler:$archLifecycleVersion"
implementation "android.arch.lifecycle:viewmodel:$archLifecycleVersion"
implementation "android.arch.lifecycle:livedata:$archLifecycleVersion"

// Room components
def room_version = "1.1.1"
implementation "android.arch.persistence.room:runtime:$room_version"
annotationProcessor "android.arch.persistence.room:compiler:$room_version" // use kapt for Kotlin
androidTestImplementation "android.arch.persistence.room:testing:$room_version"

Answer 1

为了同步检查LiveData的内容，您需要利用InstantTaskExecutorRule实例并观察LiveData实例的更改。

您可以通过注册observer来实现。

我最近在博客中发布了一个不错的解决方案here。

带有Room的Android Studio InstrumentedTest的问题

1 个答案: