libfprint/tests/README.md

umockdev Tests

umockdev tests use fingerprint devices mocked by umockdev toolchain.

This document describes how to create test cases (for USB devices). Many of these tests are tests for image devices, where a single image is captured and stored.

Other kinds of umockdev tests can be created in a similar manner. For match-on-chip devices you would instead create a test specific custom.py script, capture it and store the capture to custom.pcapng.

'capture' and 'custom' Test Creation

For image devices the capture.py script will be used to capture one reference image. If the driver is a non-image driver, then a custom.py script should be created in advance, which will be run instead.

1. Make sure that libfprint is built with support for the device driver that you want to create a test case for.

2. From the build directory, run tests/create-driver-test.py as root. Note that if you're capturing data for a driver which already has a test case but the hardware is slightly different, you might want to pass a variant name as a command-line options, for example:

$ sudo tests/create-driver-test.py driver [variant]

3. If the capture is not successful, run the tool again to start another capture.

4. Add driver test name to drivers_tests in the meson.build, as instructed, and change the ownership of the just-created test directory in the source.

5. Check whether meson test passes with this new test.

Note. To avoid submitting a real fingerprint when creating a 'capture' test, the side of finger, arm, or anything else producing an image with the device can be used.

Possible Issues

Other changes may be needed to get everything working. For example the elan driver relies on a timeout that is not reported correctly. In this case the driver works around it by interpreting the protocol error differently in the virtual environment (by means of FP_DEVICE_EMULATION environment variable).