Running UI tests

1. Running the full test suite

Note: You need Poetry, as mentioned in the core's documentation section.

In the trezor-firmware checkout, in the root of the monorepo, install the environment:

poetry install

And run the tests:

poetry run make -C core test_emu_ui

2. Running tests manually

Install the poetry environment as outlined above. Then switch to a shell inside the environment:

poetry shell

If you want to test against the emulator, run it with disabled animation in a separate terminal:

./core/ -a

Now you can run the test suite with pytest from the root directory:

pytest tests/device_tests --ui=test

If you wish to check that all test cases in fixtures.json were used set the --ui-check-missing flag. Of course this is meaningful only if you run the tests on the whole device_tests folder.

pytest tests/device_tests --ui=test --ui-check-missing

Updating Fixtures ("Recording")

Short version:

poetry run make -C core test_emu_ui_record

Long version:

The --ui pytest argument has two options:

  • record: Create screenshots and calculate theirs hash for each test. The screenshots are gitignored, but the hash is included in git.
  • test: Create screenshots, calculate theirs hash and test the hash against the one stored in git.

If you want to make a change in the UI you simply run --ui=record. An easy way to proceed is to run --ui=test at first, see what tests fail (see the Reports section below), decide if those changes are the ones you expected and then finally run the --ui=record and commit the new hashes.

Also here we provide an option to check the fixtures.json file. Use --ui-check-missing flag again to make sure there are no extra fixtures in the file:

pytest tests/device_tests --ui=record --ui-check-missing



Each --ui=test creates a clear report which tests passed and which failed. The index file is stored in tests/ui_tests/reports/test/index.html. The script tests/ starts a local HTTP server that serves this page -- this is necessary for access to browser local storage, which enables a simple reviewer UI.

On CI this report is published as an artifact. You can see the latest main branch report here. The reviewer features work directly here.

If needed, you can use python3 -m tests.ui_tests to regenerate the report from local recorded screens.

Master diff

In the ui tests folder you will also find a Python script, which creates a report where you find which tests were altered, added, or removed relative to master. This useful for Pull Requests.

This report is available as an artifact on CI as well. You can find it by visiting the "unix ui changes" job in your pipeline - browse the artifacts and open master_diff/index.html.