lazydave76 / screenshots

Screenshots: A command line utility and package for capturing screenshots for Flutter

A screenshot image with overlaid status bar and appended navigation 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.
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.

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

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/config.dart';
      import 'package:screenshots/capture_screen.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

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 list of devices to emulate
devices:
  ios:
    - iPhone X
    - iPad Pro (12.9-inch) (2nd generation)
  android:
    - Nexus 6P

# Frame screenshots
frame: true

Note: emulators and simulators corresponding to the devices in your config file must be installed on your test machine.

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: The easiest way to use Screenshots with Fastlane is to call Screenshots before calling Fastlane. Calling 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)

Changing devices

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

Make sure the devices you select have supported screens and corresponding emulators/simulators.

Note: In practice, multiple devices share the same screen size. Devices are therefore organized by supported screen size in a file called screens.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. Install an emulator or simulator for device.

Screenshots will check your configuration before running.

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 package:

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.

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 flutter/issues/27785, running Screenshots in multiple locales has limitations. This limitation is being tracked 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.