ext,tests: Allow passing of --uid to ./main.py list

This is useful for listing the fixtures of a Suite.

Change-Id: Id2f1294cc7dea03a6b26e8abc5083886fe0299d9

ext/testlib/configuration.py

@@ -751,6 +751,13 @@ class ListParser(ArgParser):
             default=False,
             help="Quiet output (machine readable).",
         ).add_to(parser)
+        Argument(
+            '--uid',
+            action='store',
+            default=None,
+            help='UID of a specific test item to list.'
+        ).add_to(parser)
+        
 
         common_args.directories.add_to(parser)
         common_args.bin_path.add_to(parser)

ext/testlib/main.py

@@ -242,7 +242,25 @@ def do_list():
 
     entry_message()
 
-    test_schedule = load_tests().schedule
+    if configuration.config.uid:
+        uid_ = uid.UID.from_uid(configuration.config.uid)
+        if isinstance(uid_, uid.TestUID):
+            log.test_log.error('Unable to list a standalone test.\n'
+                    'Gem5 expects test suites to be the smallest unit '
+                    ' of test.\n\n'
+                    'Pass a SuiteUID instead.')
+            return
+        test_schedule = loader_mod.Loader().load_schedule_for_suites(uid_)
+        if get_config_tags():
+            log.test_log.warn(
+                "The '--uid' flag was supplied,"
+                " '--include-tags' and '--exclude-tags' will be ignored."
+            )
+    else:
+        test_schedule = load_tests().schedule
+        # Filter tests based on tags
+        filter_with_config_tags(test_schedule)
+
     filter_with_config_tags(test_schedule)
 
     qrunner = query.QueryRunner(test_schedule)