fix: name the platform a typo was meant to be

scripts/common.py

@@ -350,6 +350,24 @@ def list_registered_platforms(
     return platforms
 
 
+def require_platform(name: str, platforms_dir: str = "platforms") -> None:
+    """Exit with a usable message when no platform answers to a name.
+
+    A typo used to end in a traceback (verify, cross_reference) or in "no
+    pack for batocra" after the whole build ran (generate_pack).
+    """
+    if os.path.exists(os.path.join(platforms_dir, f"{name}.yml")):
+        return
+    import difflib  # noqa: PLC0415
+
+    known = list_registered_platforms(platforms_dir, include_archived=True)
+    close = difflib.get_close_matches(name, known, n=1)
+    hint = f" Did you mean '{close[0]}'?" if close else ""
+    raise SystemExit(
+        f"ERROR: unknown platform '{name}'.{hint}\nKnown platforms: {', '.join(known)}"
+    )
+
+
 def _target_overrides(platform_name: str, targets_dir: str) -> dict:
     overrides_file = os.path.join(targets_dir, "_overrides.yml")
     if not os.path.exists(overrides_file):

scripts/cross_reference.py

@@ -20,6 +20,7 @@ from pathlib import Path
 
 sys.path.insert(0, os.path.dirname(__file__))
 from common import (
+    require_platform,
     _norm_system_id,
     directory_members,
     get_mame_clone_map,
@@ -642,6 +643,8 @@ def main():
     parser.add_argument("--target", "-t", help="Hardware target (e.g., switch, rpi4)")
     parser.add_argument("--json", action="store_true", help="JSON output")
     args = parser.parse_args()
+    if args.platform:
+        require_platform(args.platform, args.platforms_dir)
 
     profiles = load_emulator_profiles(args.emulators_dir)
     if args.emulator:

scripts/generate_pack.py

@@ -30,6 +30,7 @@ from pathlib import Path
 sys.path.insert(0, os.path.dirname(__file__))
 from common import resolve_platform_cores as _platform_cores
 from common import (
+    require_platform,
     apply_target_overrides,
     archive_entry,
     profiles_for_systems,
@@ -2846,6 +2847,9 @@ def main():
     )
     args = parser.parse_args()
     packresolve.set_offline(bool(args.offline))
+    if args.platform:
+        for name in args.platform.split(","):
+            require_platform(name.strip(), args.platforms_dir)
 
     _refuse_unapplied_flags(args, parser)
     if args.target:

scripts/verify.py

@@ -34,6 +34,7 @@ import slots
 
 sys.path.insert(0, os.path.dirname(__file__))
 from common import (
+    require_platform,
     archive_entry,
     archive_members,
     profiles_for_systems,
@@ -2064,6 +2065,8 @@ def main():
     )
     parser.add_argument("--json", action="store_true", help="JSON output")
     args = parser.parse_args()
+    if args.platform:
+        require_platform(args.platform, args.platforms_dir)
 
     requested_regions: list[str] = []
     if getattr(args, "region", None):

tests/test_system_selection.py

@@ -89,5 +89,26 @@ class ADeclinedBuildIsAFailure(unittest.TestCase):
             self.assertEqual([p for p in os.listdir(tmp) if p.endswith(".zip")], [])
 
 
+
+class AMistypedPlatformIsNamed(unittest.TestCase):
+    """verify and cross_reference ended a typo on a traceback; generate_pack
+    ran its whole build first and then said "no pack for batocra"."""
+
+    def test_every_cli_names_the_platform_it_meant(self):
+        out = Path(tempfile.mkdtemp(dir=REPO_ROOT / "tmp"))
+        out.rmdir()
+        for script, extra in (("verify.py", []), ("cross_reference.py", []),
+                              ("generate_pack.py", ["--offline", "--output-dir", str(out)])):
+            with self.subTest(script=script):
+                proc = subprocess.run(
+                    [sys.executable, f"scripts/{script}", "--platform", "batocra", *extra],
+                    capture_output=True, text=True, cwd=str(REPO_ROOT), timeout=300,
+                    check=False,
+                )
+                self.assertNotEqual(proc.returncode, 0)
+                self.assertNotIn("Traceback", proc.stderr, proc.stderr)
+                self.assertIn("Did you mean 'batocera'?", proc.stderr)
+        self.assertFalse(out.exists())
+
 if __name__ == "__main__":
     unittest.main()