Android Room Database Migration Instrumented Unit Test (Kotlin)

October 9, 2018

Edit Module build.gradle.

android {
    defaultConfig {
        ...

        javaCompileOptions {
            annotationProcessorOptions {
                arguments = ["room.schemaLocation": "$projectDir/schemas".toString()]
            }
        }
    }

    sourceSets {
        androidTest.assets.srcDirs += files("$projectDir/schemas".toString())
    }
}

dependencies {
    // existing
    implementation "android.arch.persistence.room:runtime:$android_room_version"
    kapt "android.arch.persistence.room:compiler:$android_room_version"

    // new
    androidTestImplementation "android.arch.persistence.room:testing:$android_room_version"
}

NOTE: Make sure exportSchema = true for @Database, else schema json won’t be generated and later you might bump into FileNotFoundException: Cannot find the schema file in the assets folder.

@Database(entities = [(Pin::class)], version = 1, exportSchema = true)
@TypeConverters(RoomConverters::class)
abstract class AppDatabase : RoomDatabase() {
    abstract fun pinDao(): PinDao
}

When you compile the app, assets/[DatabaseClassPath] (Android view) or /app/schemas/[DatabaseClassPath] (Project view) is generated with 1.json, 2.json, etc. (the number is the database version).

Perform Android Room database migration.

NOTE: You might want to generate 1.json by performing a compilation first, then only perform the necessary database migration (add new column/table to @Entity and change database version) to generate 2.json.

Create MigrationTest.kt in androidTest.

@RunWith(AndroidJUnit4::class)
class MigrationTest {
    companion object {
        private const val TAG = "MigrationTest"
        private const val TEST_DB = "test-db"
    }

    lateinit var db: SupportSQLiteDatabase

    @Rule @JvmField
    val helper: MigrationTestHelper = MigrationTestHelper(InstrumentationRegistry.getInstrumentation(),
            AppDatabase::class.java!!.canonicalName,
            FrameworkSQLiteOpenHelperFactory())

    @Before
    fun setUp() {
        db = helper.createDatabase(TEST_DB, 1)
    }

    @Test
    fun migrate1To2() {
        // db has schema version 1. insert some data using SQL queries.
        // You cannot use DAO classes because they expect the latest schema.
        // db.execSQL(...);
        val values = ContentValues()
        values.put("id", "test01")
        values.put("name", "Test 01")

        val id = db.insert("pin", SQLiteDatabase.CONFLICT_REPLACE, values)

        // Prepare for the next version.
        db.close()

        // Re-open the database with version 2 and provide
        // MIGRATION_1_2 as the migration process.
        db = helper.runMigrationsAndValidate(TEST_DB, 2, true, MIGRATION_1_2)

        // MigrationTestHelper automatically verifies the schema changes,
        // but you need to validate that the data was migrated properly.
        val cursor = db.query("SELECT * FROM pin WHERE rowid = ?", arrayOf(id))

        MatcherAssert.assertThat(cursor, Is(notNullValue()))
        MatcherAssert.assertThat(cursor.moveToFirst(), Is(true))

        val name = cursor.getString("name")
        MatcherAssert.assertThat(name, Is("Test 01"))

        val isLocationAccurate = cursor.getIntOrNull("is_location_accurate")
        // MatcherAssert.assertThat(isLocationAccurate, Is(nullValue()))
        MatcherAssert.assertThat(isLocationAccurate, Is(0))
    }
}

NOTE: Refer to Android Instrumented Unit Test if you are not familiar with Instrumented Unit Test.

NOTE: If you bump into duplicate column name exception, check schema/1.json and schema/2.json to make sure the new column doesn’t exist in schema/1.json.

References:

❤️ Is this article helpful?

Buy me a coffee☕ or support my work to keep this space 🖖 and ad-free.
If you can't, do send some 💖 to @d_luaz or help to share this article.

👶 Apps I built

Pixtory App (Alpha) - easily organize photos on your phone into a blog.
COVID-19 - data, chart, information & news.
暖心芽 (WIP) 🌞❤️🌱 - reminder of hope, warmth, thoughts and feelings.
Travelopy - travel discovery and journal
LuaPass - offline password manager
WhatIDoNow - a public log of things I am working on now

By Desmond Lua

A dream boy who enjoys programming and travelling, maker of Travelopy. Follow me on @d_luaz.

Tags:

Android Room Upgrade Database Add New Table (Migration) - Kotlin

Android Room Database Migration (Upgrade Version) - Kotlin

Guide to learning Android Dev with Kotlin and Architecture Components (ViewModel, LiveData and Room)

Android MD5 Test Suite / Unit Test / Test Vectors

Android Run Unit Test in Sequence (Execution Order)

Android Unit Test Handle Expected Exception (Kotlin)

Android Unit Test Androidx Migration (Kotlin)

Android Room Insert or Update

Android Room Use Nullable Variable for Embeded