bpo-30540: regrtest: add --matchfile option (#1909)

* Add a new option taking a filename to get a list of test names to
  filter tests.
* support.match_tests becomes a list.
* Modify run_unittest() to accept to match the whole test identifier,
  not just a part of a test identifier.

For example, the following command only runs test_default_timeout()
of the BarrierTests class of test_threading:

$ ./python -m test -v test_threading -m test.test_threading.BarrierTests.test_default_timeout

Remove also some empty lines from test_regrtest.py to make flake8
tool happy.

1 files changed, 19 insertions, 1 deletions

diff --git a/Lib/test/libregrtest/cmdline.py b/Lib/test/libregrtest/cmdline.py
index 8b658a4..7f66997 100644
--- a/Lib/test/libregrtest/cmdline.py
+++ b/Lib/test/libregrtest/cmdline.py
@@ -117,6 +117,13 @@ resources to test.  Currently only the following are defined:
 To enable all resources except one, use '-uall,-<resource>'.  For
 example, to run all the tests except for the gui tests, give the
 option '-uall,-gui'.
+
+--matchfile filters tests using a text file, one pattern per line.
+Pattern examples:
+
+- test method: test_stat_attributes
+- test class: FileTests
+- test identifier: test_os.FileTests.test_stat_attributes
 """
 
 
@@ -189,8 +196,12 @@ def _create_parser():
                        help='single step through a set of tests.' +
                             more_details)
     group.add_argument('-m', '--match', metavar='PAT',
-                       dest='match_tests',
+                       dest='match_tests', action='append',
                        help='match test cases and methods with glob pattern PAT')
+    group.add_argument('--matchfile', metavar='FILENAME',
+                       dest='match_filename',
+                       help='similar to --match but get patterns from a '
+                            'text file, one pattern per line')
     group.add_argument('-G', '--failfast', action='store_true',
                        help='fail as soon as a test fails (only with -v or -W)')
     group.add_argument('-u', '--use', metavar='RES1,RES2,...',
@@ -350,5 +361,12 @@ def _parse_args(args, **kwargs):
         print("WARNING: Disable --verbose3 because it's incompatible with "
               "--huntrleaks: see http://bugs.python.org/issue27103",
               file=sys.stderr)
+    if ns.match_filename:
+        if ns.match_tests is None:
+            ns.match_tests = []
+        filename = os.path.join(support.SAVEDCWD, ns.match_filename)
+        with open(filename) as fp:
+            for line in fp:
+                ns.match_tests.append(line.strip())
 
     return ns