A screenshot image with overlaid status bar placed in a device frame.

For an example of images generated with Screenshots on a live app in both stores see:

See a demo of Screenshots in action:

For introduction to Screenshots see https://medium.com/@nocnoc/automated-screenshots-for-flutter-f78be70cd5fd.

Screenshots #

Screenshots is a standalone command line utility and package for capturing screenshot images for Flutter.

Screenshots will start the required android emulators and iOS simulators (or find attached devices), run your screen capture tests on each emulator/simulator (or device), process the images, and drop them off to Fastlane for delivery to both stores.

It is inspired by three tools from Fastlane:

1. Snapshots
   This is used to capture screenshots on iOS using iOS UI Tests.
2. Screengrab
   This captures screenshots on android using Android Espresso tests.
3. FrameIt
   This is used to place captured iOS screenshots in a device frame.

Since all three of these Fastlane tools do not work with Flutter, Screenshots combines key features of these Fastlane tools into one tool.

Features #

Since Flutter integration testing is designed to work transparently across iOS and Android, capturing images using Screenshots is easy.

Features include:

1. Works with your existing tests
   Add a single line for each screenshot.
2. Run your tests on any device
   Select the devices you want to run on, using a convenient config file. Screenshots will find the devices (real or emulated) and run your tests.
3. One run for both platforms
   Screenshots runs your tests on both iOS and Android in one run.
   (as opposed to making separate Snapshots and Screengrab runs)
4. One run for multiple locales
   If your app supports multiple locales, Screenshots will optionally set the locales listed in the config file before running each test (see Limitations below).
5. One run for frames
   Optionally places images in device frames in same run.
   (as opposed to making separate FrameIt runs... which supports iOS only)
6. One run for clean status bars
   Every image that Screenshots generates has a clean status bar.
   (no need to run a separate stage to clean-up status bars)
7. Works with Fastlane
   Screenshots drops-off images where Fastlane expects to find them. Fastlane's deliver and supply can then be used to upload to respective stores.
8. Works with FrameIt
   Works with Fastlane's FrameIt text and background feature to add text, etc... to a framed screenshot generated by screenshots.
9. Works with any attached real devices
   Use any number of real devices to capture screenshots.

Additional automation features:

1. Screenshots runs in the cloud.
   For live demo of Screenshots running with the internationalized example app on macOS in cloud, see below
2. Screenshots works with any CI/CD tool.
   For live demo of uploading images, generated by Screenshots, to both store consoles, see demo of Fledge at https://github.com/mmcc007/fledge#demo

Installation #

On macOS:

$ brew update && brew install imagemagick
$ pub global activate screenshots

Note:
If pub is not found, add to PATH using:

export PATH="$PATH:<path to flutter installation directory>/bin/cache/dart-sdk/bin"

Usage #

$ screenshots

Or, if using a config file other than the default 'screenshots.yaml':

$ screenshots -c <path to config file>

Modifying your tests for Screenshots #

A special function is provided in the Screenshots package that is called by the test each time you want to capture a screenshot. Screenshots will then process the images appropriately during a Screenshots run.

To capture screenshots in your tests:

1. Include the Screenshots package in your pubspec.yaml's dev_dependencies section

     screenshots: ^<current version>
   

2. In your tests
   1. Import the dependencies

      import 'package:screenshots/screenshots.dart';
      

   2. Create the config map at start of test

           final Map config = Config().config;
      

   3. Throughout the test make calls to capture screenshots

          await screenshot(driver, config, 'myscreenshot1');
      

Note: make sure your screenshot names are unique across all your tests.

Note: to turn off the debug banner on your screens, in your integration test's main(), call:

  WidgetsApp.debugAllowBannerOverride = false; // remove debug banner for screenshots

Modifying tests based on screenshots environment #

In some cases it is useful to know what device, device type, screen size and locale you are currently testing with. To obtain this information in your test use:

final screenshotsEnv = config.screenshotsEnv;

See https://github.com/flutter/flutter/issues/31609 for related flutter driver issue.

Configuration #

Screenshots uses a configuration file to configure a run.
The default config filename is screenshots.yaml:

# A list of screen capture tests
tests:
  - test_driver/main1.dart
  - test_driver/main2.dart

# Note: flutter driver expects a pair of files for testing
# For example:
#   main1.dart is the test app (that calls your app)
#   main1_test.dart is the matching test that flutter driver 
#   expects to find.

# Interim location of screenshots from tests
staging: /tmp/screenshots

# A list of locales supported by the app
locales:
  - de-DE
  - en-US

# A map of devices to emulate
devices:
  ios:
    iPhone XS Max:
      frame: false
    iPad Pro (12.9-inch) (3rd generation):
  android:
    Nexus 6P:

# Frame screenshots
frame: true

Device Parameters #

Individual devices can be configured in screenshots.yaml by specifying per device parameters.

Note: images generated for those devices where framing is disabled are probably not suitable for upload, but can be used for local review.

Integration with Fastlane #

Since Screenshots is intended to be used with Fastlane, after Screenshots completes, the images can be found in your project at:

android/fastlane/metadata/android
ios/fastlane/screenshots

Images are in a format suitable for upload via deliver and supply.

Tip: One way to use Screenshots with Fastlane is to call Screenshots before calling Fastlane (or optionally call from Fastlane). Fastlane (for either iOS or Android) will then find the images in the appropriate place.

(For a live demo of using Fastlane to upload screenshot images to both store consoles, see demo of Fledge at https://github.com/mmcc007/fledge#demo)

Fastlane FrameIt #

iOS images generated by Screenshots can also be further processed using FrameIt's text and background feature.

Changing devices #

To change the devices to run your tests on, just change the list of devices in screenshots.yaml.

Make sure each device you select has a supported screen and a corresponding attached device or installed emulator/simulator. To bypass this requirement use frame: false for each related device in your screenshots.yaml.

For each selected device:

1. Confirm device is present in screens.yaml.
2. Add device to the list of devices in screenshots.yaml.
3. Confirm a real device is attached, or install an emulator/simulator for device.

Config validation #

Screenshots will check your configuration before running for any errors and provide a guide on how to resolve.

Upgrading #

To upgrade, simply re-issue the install command

$ pub global activate screenshots

Note: the Screenshots version should be the same for both the command line and in your pubspec.yaml.

1. If upgrading the command line version of Screenshots, also upgrade the version of Screenshots in your pubspec.yaml.
2. If upgrading the version of Screenshots in your pubspec.yaml, also upgrade the command line version.

To check the version of Screenshots currently installed:

pub global list

Sample run on Travis #

To view Screenshots running with the internationalized example app on macOS in the cloud see:
https://travis-ci.com/mmcc007/screenshots

To view the images generated by Screenshots during run on travis see:
https://github.com/mmcc007/screenshots/releases/

• Running Screenshots in the cloud is useful for automating the generation of your screenshots in a CI/CD environment.
• Running Screenshots on macOS in the cloud can be used to generate your screenshots when developing on Linux and/or Windows (if not using locally attached iOS devices).

Limitations #

Due to a Flutter issue (flutter/issues/27785), running Screenshots in multiple locales has limitations.

To raise priority of this Flutter issue, so it will be fixed sooner rather than later, please give a thumbs-up on flutter/issues/27785.

Priority of this limitation in Flutter project:

(This limitation is being tracked by screenshots in screenshots/issues/20).

Issues and Pull Requests #

Issues and pull requests are welcome.

Your feedback is welcome and is used to guide where development effort is focused. So feel free to create as many issues and pull requests as you want. You should expect a timely and considered response.