feat: patrol on-device integration smoke test

android/app/build.gradle.kts

@@ -25,6 +25,25 @@ android {
         targetSdk = flutter.targetSdkVersion
         versionCode = flutter.versionCode
         versionName = flutter.versionName
+        // The Android Test Orchestrator (with clearPackageData) wipes the
+        // integration flavor's app data between test runs, and the flavor
+        // installs it beside — never over — the real app, so every patrol run
+        // starts at onboarding with a fresh identity.
+        testInstrumentationRunner = "pl.leancode.patrol.PatrolJUnitRunner"
+        testInstrumentationRunnerArguments["clearPackageData"] = "true"
+    }
+
+    testOptions {
+        execution = "ANDROIDX_TEST_ORCHESTRATOR"
+    }
+
+    flavorDimensions += "test"
+    productFlavors {
+        create("integration") {
+            dimension = "test"
+            applicationIdSuffix = ".integration"
+            versionNameSuffix = "-integration"
+        }
     }
 
     buildTypes {
@@ -38,3 +57,10 @@ android {
 flutter {
     source = "../.."
 }
+
+dependencies {
+    // The orchestrator referenced by testOptions.execution above. The patrol
+    // native library itself comes from the patrol pub package's android
+    // module (a plugin subproject), not from a Maven artifact.
+    androidTestUtil("androidx.test:orchestrator:1.5.1")
+}

android/app/src/androidTest/java/com/app/smol_mail/integration/MainActivityTest.java

@@ -0,0 +1,38 @@
+package com.app.smol_mail.integration;
+
+import androidx.test.platform.app.InstrumentationRegistry;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.Parameterized;
+import org.junit.runners.Parameterized.Parameters;
+import pl.leancode.patrol.PatrolJUnitRunner;
+
+// The Patrol host class: each Dart test in the integration_test directory is
+// executed through this JUnit suite. Its package is the flavored applicationId
+// (com.app.smol_mail + .integration suffix); the namespace differs, so
+// MainActivity needs the explicit import below.
+@RunWith(Parameterized.class)
+public class MainActivityTest {
+
+    @Parameters(name = "{0}")
+    public static Object[] testCases() {
+        PatrolJUnitRunner instrumentation =
+                (PatrolJUnitRunner) InstrumentationRegistry.getInstrumentation();
+        instrumentation.setUp(com.example.smol_mail.MainActivity.class);
+        instrumentation.waitForPatrolAppService();
+        return instrumentation.listDartTests();
+    }
+
+    public MainActivityTest(String dartTestName) {
+        this.dartTestName = dartTestName;
+    }
+
+    private final String dartTestName;
+
+    @Test
+    public void runDartTest() {
+        PatrolJUnitRunner instrumentation =
+                (PatrolJUnitRunner) InstrumentationRegistry.getInstrumentation();
+        instrumentation.runDartTest(dartTestName);
+    }
+}