Add support for test sharding (#272)

* Add a common testutil module for shared helpers

* Introduce ShardingFilter and mirror support for 'numShards' and 'shardIndex'

build-logic/src/main/kotlin/Dependencies.kt

@@ -43,6 +43,7 @@ object libs {
     const val mockitoKotlin = "com.nhaarman.mockitokotlin2:mockito-kotlin:2.2.0"
     const val truth = "com.google.truth:truth:${versions.truth}"
     const val truthJava8Extensions = "com.google.truth.extensions:truth-java8-extension:${versions.truth}"
+    const val robolectric = "org.robolectric:robolectric:4.8.1"
 
     const val androidXTestCore = "androidx.test:core:${versions.androidXTest}"
     const val androidXTestRunner = "androidx.test:runner:${versions.androidXTest}"

instrumentation/CHANGELOG.md

@@ -3,6 +3,7 @@ Change Log
 
 ## Unreleased
 - Update formatting of instrumentation test names to prevent breaking generation of log files in newer versions of AGP (#263)
+- Add support for test sharding (#270)
 
 ## 1.3.0 (2021-09-17)
 

instrumentation/core/build.gradle.kts

@@ -108,11 +108,7 @@ dependencies {
   androidTestRuntimeOnly(project(":runner"))
   androidTestRuntimeOnly(libs.junitJupiterEngine)
 
-  testImplementation(libs.junitJupiterApi)
-  testImplementation(libs.mockitoCore)
-  testImplementation(libs.mockitoKotlin)
-  testImplementation(libs.truth)
-  testImplementation(libs.truthJava8Extensions)
+  testImplementation(project(":testutil"))
 }
 
 project.configureDeployment(Artifacts.Instrumentation.Core)

instrumentation/core/src/test/java/de/mannodermaus/junit5/condition/DisabledIfBuildConfigValueConditionTests.kt

@@ -2,7 +2,7 @@ package de.mannodermaus.junit5.condition
 
 import com.google.common.truth.Truth.assertThat
 import de.mannodermaus.junit5.internal.DisabledIfBuildConfigValueCondition
-import de.mannodermaus.junit5.util.AndroidBuildUtils.withMockedInstrumentation
+import de.mannodermaus.junit5.testutil.AndroidBuildUtils.withMockedInstrumentation
 import de.mannodermaus.junit5.util.RESOURCE_LOCK_INSTRUMENTATION
 import org.junit.jupiter.api.Test
 import org.junit.jupiter.api.assertThrows

instrumentation/core/src/test/java/de/mannodermaus/junit5/condition/DisabledOnManufacturerConditionTests.kt

@@ -2,7 +2,7 @@ package de.mannodermaus.junit5.condition
 
 import com.google.common.truth.Truth.assertThat
 import de.mannodermaus.junit5.internal.DisabledOnManufacturerCondition
-import de.mannodermaus.junit5.util.AndroidBuildUtils.withManufacturer
+import de.mannodermaus.junit5.testutil.AndroidBuildUtils.withManufacturer
 import org.junit.jupiter.api.Test
 import org.junit.jupiter.api.assertThrows
 import org.junit.jupiter.api.extension.ExecutionCondition

instrumentation/core/src/test/java/de/mannodermaus/junit5/condition/DisabledOnSdkVersionConditionTests.kt

@@ -2,7 +2,7 @@ package de.mannodermaus.junit5.condition
 
 import com.google.common.truth.Truth.assertThat
 import de.mannodermaus.junit5.internal.DisabledOnSdkVersionCondition
-import de.mannodermaus.junit5.util.AndroidBuildUtils.withApiLevel
+import de.mannodermaus.junit5.testutil.AndroidBuildUtils.withApiLevel
 import org.junit.jupiter.api.Test
 import org.junit.jupiter.api.assertThrows
 import org.junit.jupiter.api.extension.ExecutionCondition

instrumentation/core/src/test/java/de/mannodermaus/junit5/condition/EnabledIfBuildConfigValueConditionTests.kt

@@ -2,7 +2,7 @@ package de.mannodermaus.junit5.condition
 
 import com.google.common.truth.Truth.assertThat
 import de.mannodermaus.junit5.internal.EnabledIfBuildConfigValueCondition
-import de.mannodermaus.junit5.util.AndroidBuildUtils.withMockedInstrumentation
+import de.mannodermaus.junit5.testutil.AndroidBuildUtils.withMockedInstrumentation
 import de.mannodermaus.junit5.util.RESOURCE_LOCK_INSTRUMENTATION
 import org.junit.jupiter.api.Test
 import org.junit.jupiter.api.assertThrows

instrumentation/core/src/test/java/de/mannodermaus/junit5/condition/EnabledOnManufacturerConditionTests.kt

@@ -2,7 +2,7 @@ package de.mannodermaus.junit5.condition
 
 import com.google.common.truth.Truth.assertThat
 import de.mannodermaus.junit5.internal.EnabledOnManufacturerCondition
-import de.mannodermaus.junit5.util.AndroidBuildUtils.withManufacturer
+import de.mannodermaus.junit5.testutil.AndroidBuildUtils.withManufacturer
 import org.junit.jupiter.api.Test
 import org.junit.jupiter.api.assertThrows
 import org.junit.jupiter.api.extension.ExecutionCondition

instrumentation/core/src/test/java/de/mannodermaus/junit5/condition/EnabledOnSdkVersionConditionTests.kt

@@ -2,7 +2,7 @@ package de.mannodermaus.junit5.condition
 
 import com.google.common.truth.Truth.assertThat
 import de.mannodermaus.junit5.internal.EnabledOnSdkVersionCondition
-import de.mannodermaus.junit5.util.AndroidBuildUtils.withApiLevel
+import de.mannodermaus.junit5.testutil.AndroidBuildUtils.withApiLevel
 import org.junit.jupiter.api.Test
 import org.junit.jupiter.api.assertThrows
 import org.junit.jupiter.api.extension.ExecutionCondition

instrumentation/runner/build.gradle.kts

@@ -105,12 +105,9 @@ dependencies {
   compileOnly(libs.junitJupiterParams)
   compileOnly(libs.junitPlatformRunner)
 
-  testImplementation(libs.truth)
-  testImplementation(libs.mockitoCore)
-  testImplementation(libs.junitJupiterApi)
-  testImplementation(libs.junitJupiterParams)
-  testImplementation(libs.junitPlatformRunner)
-
+  testImplementation(project(":testutil"))
+  testImplementation(libs.robolectric)
+  testRuntimeOnly(libs.junitVintageEngine)
   testRuntimeOnly(libs.junitJupiterEngine)
 }
 

instrumentation/runner/src/main/kotlin/de/mannodermaus/junit5/internal/discovery/GeneratedFilters.kt

@@ -38,7 +38,7 @@ internal object GeneratedFilters {
         }
 
         if (inputStream == null) {
-            // File does't exist, or couldn't be located; return
+            // File doesn't exist, or couldn't be located; return
             return emptyList()
         }
 

instrumentation/runner/src/main/kotlin/de/mannodermaus/junit5/internal/discovery/ShardingFilter.kt

@@ -0,0 +1,53 @@
+package de.mannodermaus.junit5.internal.discovery
+
+import android.os.Bundle
+import de.mannodermaus.junit5.internal.extensions.isDynamicTest
+import org.junit.platform.engine.FilterResult
+import org.junit.platform.engine.TestDescriptor
+import org.junit.platform.launcher.PostDiscoveryFilter
+import org.junit.platform.launcher.TestIdentifier
+import kotlin.math.abs
+
+/**
+ * JUnit 5 implementation of the default instrumentation's
+ * `androidx.test.internal.runner.TestRequestBuilder$ShardingFilter`,
+ * ported to the new API to support dynamic test templates, too.
+ *
+ * Based on a draft by KyoungJoo Jeon (@jkj8790).
+ */
+internal class ShardingFilter(
+    private val numShards: Int,
+    private val shardIndex: Int,
+) : PostDiscoveryFilter {
+
+    companion object {
+        private const val ARG_NUM_SHARDS = "numShards"
+        private const val ARG_SHARD_INDEX = "shardIndex"
+
+        fun fromArguments(arguments: Bundle): ShardingFilter? {
+            val numShards = arguments.getString(ARG_NUM_SHARDS)?.toInt() ?: -1
+            val shardIndex = arguments.getString(ARG_SHARD_INDEX)?.toInt() ?: -1
+
+            return if (numShards > 0 && shardIndex >= 0 && shardIndex < numShards) {
+                ShardingFilter(numShards, shardIndex)
+            } else {
+                null
+            }
+        }
+    }
+
+    override fun apply(descriptor: TestDescriptor): FilterResult {
+        val identifier = TestIdentifier.from(descriptor)
+
+        if (identifier.isTest || identifier.isDynamicTest) {
+            val remainder = abs(identifier.hashCode()) % numShards
+            return if (remainder == shardIndex) {
+                FilterResult.included(null)
+            } else {
+                FilterResult.excluded("excluded")
+            }
+        }
+
+        return FilterResult.included(null)
+    }
+}

instrumentation/runner/src/main/kotlin/de/mannodermaus/junit5/internal/runners/AndroidJUnit5RunnerParams.kt

@@ -4,6 +4,7 @@ import androidx.test.platform.app.InstrumentationRegistry
 import de.mannodermaus.junit5.internal.discovery.GeneratedFilters
 import de.mannodermaus.junit5.internal.discovery.ParsedSelectors
 import de.mannodermaus.junit5.internal.discovery.PropertiesParser
+import de.mannodermaus.junit5.internal.discovery.ShardingFilter
 import org.junit.platform.engine.DiscoverySelector
 import org.junit.platform.engine.Filter
 import org.junit.platform.engine.discovery.MethodSelector
@@ -60,7 +61,8 @@ internal fun createRunnerParams(testClass: Class<*>): AndroidJUnit5RunnerParams
     // which aren't subject to the filtering imposed through adb.
     // A special resource file may be looked up at runtime, containing
     // the filters to apply by the AndroidJUnit5 runner.
-    val filters = GeneratedFilters.fromContext(instrumentation.context)
+    val filters = GeneratedFilters.fromContext(instrumentation.context) +
+            listOfNotNull(ShardingFilter.fromArguments(arguments))
 
     return AndroidJUnit5RunnerParams(
         selectors,