* Copyright (C) 2015 The Android Open Source Project
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* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
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INTRODUCTION

The Android theme tests ensure that the Holo and Material themes have not been
modified. They consist of API-specific sets of reference images representing
specific themes and widgets that must be identical across devices. To pass the
theme tests, a device must be able to generate images that are identical to the
reference images.

NOTE: Reference images should only be updated by the CTS test maintainers. Any
      modifications to the reference images will invalidate the test results.


INSTRUCTIONS

I. Generating reference images (CTS maintainers only)

Reference images are typically only generated for new API revisions. To
generate a new set of reference images from an emulator, do the following:

  1. Ensure the Android SDK is installed locally. Either a public or internal
     distribution is fine. From the console, set the ANDROID_SDK_ROOT env var:

     export ANDROID_SDK_ROOT = /path/to/sdk

  2. Obtain an x86_64 emulator image from the build server by using the script
     available internally at go/emu-dev. This script will install the image in
     your SDK.

  3. Use the SDK's AVD Manager tool to create a single virtual device using the
     emulator image from step 2. The exact configuration doesn't really matter;
     you can use Nexus 5 as a template. Name the emulator "theme_emulator".

  4. From the console, set up your build environment for x86_64 and build CTS:

     lunch sdk_x86_64-eng && make cts -j32

  5. Use the reference image script to generate the reference images. The script
     will automatically start the emulator in the required configurations and
     install the resulting reference images in assets/<platform>/<dpi>.zip,
     overwriting any existing images.

     ./cts/hostsidetests/theme/generate_images.py theme_emulator

You can also generate reference images using a real device. To generate a new set
of reference images from a real device, do the following:

  1. Connect the device. Verify the device is connected:

     adb devices

  2. Use the reference image script to generate the reference images:

     ./cts/hostsidetests/theme/generate_images.py

There is an option to build locally an Android system image and use an emulator that is stored in
Android source tree under "prebuilts/android-emulator/linux-x86_64/emulator". This option does not
require a SDK and can be used to generate images with locally modified source code: for example
right before making a test breaking change.

  1. From the console, set up your build environment for sdk_phone_x86_64 and build Android and CTS:

     lunch sdk_phone_x86_64-userdebug && make -j32 && make cts -j32

  2. Use the reference image script to generate the reference images. The script
     will automatically start the emulator in the required configurations and
     install the resulting reference images in assets/<platform>/<dpi>.zip,
     overwriting any existing images.

     ./cts/hostsidetests/theme/generate_images.py local

A complete collection of reference images for a given API revision must include
a set for each possible DPI bucket (tvdpi, xxhdpi, etc.) that may be tested.

For a list of devices and their DPI buckets, see Device Metrics:

    https://design.google.com/devices/


II. Building theme tests

1. If you have not already built the CTS tests, run an initial make:

   make cts -j32

2. Subsequent changes to the theme tests, including changes to the reference
   images, may be built using mmm:

   mmm cts/hostsidetests/theme -j32


III. Running theme tests

To obtain reliable results, theme tests should be run against the device's
native density; however, many of the tests will also work in a scaled density.
If you don't possess a device for a given density and would still like to run
tests for that density, you can manually force scaling via:

  adb shell wm density <dpi>

As of API 24, the results will NOT be 100% reliable due to scaling artifacts.
To reset the device to its native density, run:

  adb shell wm density reset

Once the device is in the desired state, do the following:

  1. Connect the device that you wish to test. Confirm that is is connected with:

     adb devices

  2. Run the theme tests using cts-tradefed:

     cts-tradefed run singleCommand cts-dev --module CtsThemeHostTestCases \
         --test android.theme.cts.ThemeHostTest

  3. Wait for the tests to complete. This should take less than five minutes.

If any test failures are encountered, diff PNGs will be generated and collected
in the "diffs" directory of the CTS results indicated by "Test Result:" in the
test output.