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Flutter Dart Testing On LambdaTest - Android

Flutter, an open-source UI toolkit created by Google, is a popular choice among developers to build natively compiled applications for mobile, web, and desktop from a single codebase. With Dart as its programming language, Flutter enables fast development of beautiful apps with a highly productive, extensible and open-source set of features.

In this guide, we will explore how to run your first Flutter Dart test on an Android device using the LambdaTest Real Device Cloud. By combining the capabilities of Flutter Dart and LambdaTest, you can ensure the proper functioning of your app across different devices and make your app more reliable and robust.

Prerequisites for Getting Started​

  1. Flutter SDK installed on your system
  2. You will need a LambdaTest username and access key. To obtain your access credentials, purchase a plan or access the automation dashboard.
  3. Access to an android Sample app (.apk) and an Sample Test Suite app (.apk file).
tip

If you do not have any Flutter Android app (.apk) and an Flutter Test Suite app (.apk) file, you can run your sample tests on LambdaTest by using our sample 🔗 Android app and a sample 🔗 Test Suite.

Run Your First Test​

Step 1: Create your Android Flutter app and test suite for testing​

For testing, you need to build a Flutter app and test suite. You can create Flutter applications and test suites using either Flutter cli or Gradlew. The steps below demonstrate how to create apks with Gradlew.

  • Create an instrumentation test file in your application's directory android/app/src/androidTest/java/com/example/lambdatestSampleApp/. Replace com, example, and lambdatestSampleApp values with those from your app's package name.

    SampleTest.java
    package com.example.lambdatestSampleApp;
        import androidx.test.rule.SampleTestRule;
        import dev.flutter.plugins.integration_test.FlutterTestRunner;
        import org.junit.Rule;
        import org.junit.runner.RunWith;
        import com.example.lambdatestSampleApp.Sample;
        @RunWith(FlutterTestRunner.class)
        public class SampleTest {
          @Rule
          public SampleTestRule<Sample> rule = new SampleTestRule<>(Sample.class, true, false);
        }

  • Update your application's lambdatestSampleApp/android/app/build.gradle file to use androidx's version of AndroidJUnitRunner and include the androidx libraries as dependencies.

    build.gradle
    android {
          ...
          defaultConfig {
            ...
            testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
          }
        }
        dependencies {
            testImplementation 'junit:junit:4.12'
            androidTestImplementation 'androidx.test:runner:1.2.0'
            androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0'
        }

  • Use the following Gradle commands to build an instrumentation test.apk file(test suite) using the Sample.java created in the androidTest directory as mentioned in step 1.

    Terminal
    //Go to the android folder which contains the "gradlew" script used for building Android apps from the terminal
    pushd android
    //Build an Android test APK (uses the Sample.java file created in step 1)
    ./gradlew app:assembleAndroidTest
    //Build a debug APK by passing the integration test file
    ./gradlew app:assembleDebug -Ptarget="INTEGRATION_TEST_FILE_PATH"
    //Go back to the root of the project
    popd
info

Avoiding this step might result in No Tests Ran issue on the dashboard

To create APKs with optional Flutter parameters, first run the Flutter tests in verbose mode with the flutter cli. This allows you to see the Gradle command used internally to build the APKs.

For example, to use --no-sound-null-safety in your tests, run the following command.

flutter run -v --no-sound-null-safety

Next, look for gradlew execution in the logs. The above command generates a gradlew command in the logs that looks something like the following. To build your apk files, replace the parameter YOUR_APP_PATH with your actual path of the application in the following command:

gradlew --full-stacktrace --info -Pverbose=true -Ptarget-platform=android-arm64 -Ptarget=YOUR_APP_PATH/lib/main.dart -Pbase-application-name=android.app.Application -Pdart-obfuscation=false -Pextra-front-end-options=--no-sound-null-safety -Ptrack-widget-creation=true -Ptree-shake-icons=false -Pfilesystem-scheme=org-dartlang-root assembleDebug

Step 2: Upload Your Application​

Upload your android application (.apk file) to the LambdaTest servers using our REST API. You need to provide your Username and AccessKey in the format Username:AccessKey in the cURL command for authentication. Make sure to add the path of the appFile in the cURL request. Here is an example cURL request to upload your app using our REST API:

Using App File:

curl -u "undefined:undefined" \
--location --request POST 'https://manual-api.lambdatest.com/app/uploadFramework' --form 'appFile=@"/Users/macuser/Downloads/sample-flutter-app.apk"' --form 'type="flutter-android"'
note

Response of above cURL will be a JSON object containing the App URL of the format - lt://APP123456789123456789123456789 and will be used in the last step.

Step 3: Uploading Test Suite​

Upload your test suite (.apk file) to the LambdaTest servers using our REST API. You need to provide your Username and AccessKey in the format Username:AccessKey in the cURL command for authentication. Make sure to add the path of the appFile in the cURL request. Here is an example cURL request to upload your app using our REST API:

Using App File:

curl -u "undefined:undefined" \
--location --request POST 'https://manual-api.lambdatest.com/app/uploadFramework' --form 'appFile=@"/Users/macuser/Downloads/sample-flutter-testsuite.apk"' --form 'type="flutter-android"'
note

Response of above cURL will be a JSON object containing the App URL of the format - lt://APP123456789123456789123456789 and will be used in the next step.

Step 4: Executing The Test​

Basic Authentication​

info

You will need base64 encoded authentication in order to execute your Espresso automation test suite. You need to enter your username:accesskey here in order and click on encode to generate the base64 authentication. Take note of the base64 encoded authentication which needs to be added in the next step.

undefined:undefined

Execute Command​

Once you have uploaded your app and test suite, you need to you can execute your test by running the following command:

info

Make sure to enter your basic authentication, app url (generated in the first step) and testSuite url (generated in the second step) in the below command.

curl --location --request POST 'https://mobile-api.lambdatest.com/framework/v1/flutter/android/build' \
--header 'Authorization: Basic <Enter_Basic_Auth>' \
--header 'Content-Type: application/json' \
--data-raw '{
    "app" : "lt://APP_ID",
    "testSuite": "lt://TestSuite_ID",
    "device" :  ["Galaxy S21 5G-12"],
    "deviceLog": true,
    "network": false,
    "build" : "Sample-Flutter"
}'

Step 5: View Test Execution​

Once you have run your tests, you can view the test execution along with logs. You will be able to see the test cases passing or failing. You can view the same at LambdaTest Automation.

Running Tests in Parallel​

You can run tests in parallel on multiple devices by passing the device name in comma separated format in the execute command as show below:

curl --location --request POST 'https://mobile-api.lambdatest.com/framework/v1/flutter/android/build' \
--header 'Authorization: Basic <Enter_Basic_Auth>' \
--header 'Content-Type: application/json' \
--data-raw '{
    "app" : "app_id",
    "testSuite": "testsuite_id",
    "device" :  ["Galaxy S22 5G-12","Galaxy S24-14","Pixel 7-13","Galaxy S10+-10"],
    "queueTimeout": 10800,
    "testTimeout": 900,
    "deviceLog": true,
    "build" : "Sample-Flutter",
}'
note

Do note that Flutter builds when run in parallel, result in separate builds being generated for each parallel run.

Auto-Grant Permissions for Android Apps​

While testing Android apps, user might need to handle various pop-ups or dialogs asking for permissions like contacts, notifications, photos, etc.

To simplify this process, set Flutter's autoGrantPermissions parameter to automatically grant the required permissions based on the Android manifest in the app’s .APK file.Please find a example cURL request to enable autoGrantPermissions:

curl --location --request POST 'https://mobile-api.lambdatest.com/framework/v1/flutter/android/build' \
--header 'Authorization: Basic <Enter_Basic_Auth>' \
--header 'Content-Type: application/json' \
--data-raw '{
    "app" : "app_id",
    "testSuite": "testsuite_id",
    "device" :  ["Galaxy S22 5G-12"]
    "queueTimeout": 10800,
    "testTimeout": 900,
    "deviceLog": true,
    "build" : "Sample-Flutter",
    "autoGrantPermissions" : true
}'
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