* Copyright (C) 2015 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
*      http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.


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, do the following:

  1. Connect one device for each DPI bucket (ldpi, xxxhdpi, etc.) that you wish
     to generate references images for. Confirm that all devices are connected
     with:

     adb devices

  2. Image generation occurs on all devices in parallel. Resulting sets of
     reference images are saved in assets/<platform>/<dpi>.zip and will
     overwrite any existing sets. Image generation may be started using:

     ./cts/hostsidetests/theme/generate_images.sh

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.