tests: Run custom.py from test creation helper when available

This allows creating tests both for image and non-image devices using
the same script.

tests/README.md

@@ -3,20 +3,23 @@
 `umockdev` tests use fingerprint devices mocked by [`umockdev`
 toolchain][umockdev].
 
-This document describes how to create a 'capture' test: a test that
+This document describes how to create test cases (for USB devices). Many of
-captures a picture of a fingerprint from the device (mocked by
+these tests are tests for image devices, where a single image is captured
-`umockdev`) and compares it with the standard one.
+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' Test Creation
+'capture' and 'custom' Test Creation
------------------------
+------------------------------------
-A new 'capture' test is created by means of `capture.py` script:
+
+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 capture a test case for.
+   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
@@ -33,8 +36,9 @@ $ sudo tests/create-driver-test.py driver [variant]
 
 5. Check whether `meson test` passes with this new test.
 
-**Note.** To avoid submitting a real fingerprint, the side of finger,
+**Note.** To avoid submitting a real fingerprint when creating a 'capture' test,
-arm, or anything else producing an image with the device can be used.
+the side of finger, arm, or anything else producing an image with the device
+can be used.
 
 
 Possible Issues

tests/create-driver-test.py.in

@@ -37,6 +37,7 @@ def print_usage():
     print(f'Usage: {sys.argv[0]} driver [test-variant-name]')
     print('A test variant name is optional, and must be all lower case letters, or dashes, with no spaces')
     print(f'The captured data will be stored in {SRCDIR}/tests/[driver name]-[test variant name]')
+    print(f'Create custom.py prior to execution for non image device tests.')
 
 if len(sys.argv) > 3:
     print_usage()
@@ -118,7 +119,13 @@ if capture_pid == 0:
 time.sleep(1)
 
 print('### Capturing fingerprint, please swipe or press your finger on the reader')
-with subprocess.Popen(['python3', SRCDIR + '/tests/capture.py', test_dir + '/capture.png']) as capture_process:
+cmd = ['python3', SRCDIR + '/tests/capture.py', test_dir + '/capture.png']
+capture_file = 'capture.pcapng' # capture for "capture" test
+if os.path.exists(os.path.join(test_dir, "custom.py")):
+    cmd = ['python3', os.path.join(test_dir, "custom.py")]
+    capture_file = "custom.pcapng"
+
+with subprocess.Popen(cmd) as capture_process:
     capture_process.wait()
     if capture_process.returncode != 0:
         print('Failed to capture fingerprint')
@@ -155,7 +162,7 @@ except ChildProcessError:
 # Filter the capture
 print(f'\n### Saving USB capture as test case {test_name}')
 args = ['tshark', '-r', unfiltered_cap_path, '-Y', f'usb.bus_id == {bus_num} and usb.device_address == {device_num}',
-        '-w', test_dir + '/capture.pcapng']
+        '-w', os.path.join(test_dir, capture_file)]
 with subprocess.Popen(args, stderr=subprocess.DEVNULL) as filter_process:
     filter_process.wait()