iotests/linters: Add entry point for linting via Python CI

We need at least a tiny little shim here to join test file discovery
with test invocation. This logic could conceivably be hosted somewhere
in python/, but I felt it was strictly the least-rude thing to keep the
test logic here in iotests/, even if this small function isn't itself an
iotest.

Note that we don't actually even need the executable bit here, we'll be
relying on the ability to run this module as a script using Python CLI
arguments. No chance it gets misunderstood as an actual iotest that way.

(It's named, not in tests/, doesn't have the execute bit, and doesn't
have an execution shebang.)

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Message-id: 20211019144918.3159078-13-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>

tests/qemu-iotests/linters.py

@@ -16,6 +16,7 @@
 import os
 import re
 import subprocess
+import sys
 from typing import List, Mapping, Optional
 
 
@@ -74,3 +75,29 @@ def run_linter(
         stderr=subprocess.STDOUT if suppress_output else None,
         universal_newlines=True,
     )
+
+
+def main() -> None:
+    """
+    Used by the Python CI system as an entry point to run these linters.
+    """
+    def show_usage() -> None:
+        print(f"Usage: {sys.argv[0]} < --mypy | --pylint >", file=sys.stderr)
+        sys.exit(1)
+
+    if len(sys.argv) != 2:
+        show_usage()
+
+    files = get_test_files()
+
+    if sys.argv[1] == '--pylint':
+        run_linter('pylint', files)
+    elif sys.argv[1] == '--mypy':
+        run_linter('mypy', files)
+    else:
+        print(f"Unrecognized argument: '{sys.argv[1]}'", file=sys.stderr)
+        show_usage()
+
+
+if __name__ == '__main__':
+    main()