fix: suggest a region for an unknown spelling

install.ps1

@@ -8,7 +8,7 @@ param(
 
 $ErrorActionPreference = "Stop"
 $defaultInstallUrl = "https://raw.githubusercontent.com/Abdess/retrobios/main/install.py"
-$defaultInstallSha256 = "a7c7a25573c6c96beb63eebbc079956dca4f173b9cc8aa6397935654ddc23f71"
+$defaultInstallSha256 = "f2a35f8df5956bb8b7ff1d697c0c204688d911a8942477b6d084882a92349a3b"
 $maximumInstallerBytes = 2MB
 $installerExit = 0
 $installer = if ($PSScriptRoot) { Join-Path $PSScriptRoot "install.py" } else { $null }

install.py

@@ -1716,7 +1716,14 @@ def canonical_region(raw: str) -> str:
     key = raw.strip().lower()
     key = REGION_ALIASES.get(key, key)
     if key not in REGIONS:
-        raise ValueError(f"unknown region: {raw.strip()}")
+        import difflib  # noqa: PLC0415
+
+        close = difflib.get_close_matches(key, [*REGION_ALIASES, *REGIONS], n=3, cutoff=0.5)
+        hint = f" Did you mean: {', '.join(close)}?" if close else ""
+        raise ValueError(
+            f"unknown region: {raw.strip()}.{hint} "
+            f"Short forms: {', '.join(REGION_ALIASES)}; regions: {', '.join(sorted(REGIONS))}"
+        )
     return key
 
 
@@ -2945,7 +2952,7 @@ def main() -> None:
         try:
             resolve_regions(args.region)
         except ValueError as exc:
-            parser.error(f"{exc} (known: {', '.join(sorted(REGIONS))})")
+            parser.error(str(exc))
     for option, values in (("--system", args.system), ("--core", args.core)):
         if values is not None and not any(
             token.strip() for value in values for token in value.split(",")

install.sh

@@ -18,7 +18,7 @@ esac
 TEMP_INSTALLER=""
 TEMP_DIRECTORY=""
 DEFAULT_INSTALL_URL="https://raw.githubusercontent.com/Abdess/retrobios/main/install.py"
-DEFAULT_INSTALL_SHA256="a7c7a25573c6c96beb63eebbc079956dca4f173b9cc8aa6397935654ddc23f71"
+DEFAULT_INSTALL_SHA256="f2a35f8df5956bb8b7ff1d697c0c204688d911a8942477b6d084882a92349a3b"
 MAX_INSTALLER_BYTES=2097152
 
 cleanup() {

scripts/region.py

@@ -70,12 +70,28 @@ ALIASES: dict[str, str] = {
 }
 
 
+def unknown_region_message(raw: str, aliases: dict[str, str], regions: frozenset[str]) -> str:
+    """What to type instead: the closest spellings, then every short form.
+
+    `unknown region: 'uss'` left the user to read the source for `us`.
+    """
+    import difflib  # noqa: PLC0415
+
+    spelled = raw.strip()
+    close = difflib.get_close_matches(spelled.lower(), [*aliases, *regions], n=3, cutoff=0.5)
+    hint = f" Did you mean: {', '.join(close)}?" if close else ""
+    return (
+        f"unknown region: {spelled}.{hint} Short forms: {', '.join(aliases)}; "
+        f"regions: {', '.join(sorted(regions))}"
+    )
+
+
 def _canonical(raw: str) -> str:
     """Map one token to a canonical region slug."""
     key = raw.strip().lower()
     key = ALIASES.get(key, key)
     if key not in REGIONS:
-        raise ValueError(f"unknown region: {raw!r}")
+        raise ValueError(unknown_region_message(raw, ALIASES, REGIONS))
     return key
 
 

tests/test_region.py

@@ -910,5 +910,32 @@ class EmulatorModeKeepsAHeldFile(unittest.TestCase):
         )
 
 
+
+class UnknownRegionSaysWhatToType(unittest.TestCase):
+    """`unknown region: 'uss'` named nothing to type instead."""
+
+    def test_the_build_scripts_suggest_and_list_short_forms(self):
+        import region
+
+        with self.assertRaises(ValueError) as caught:
+            region.parse_requested("uss")
+        message = str(caught.exception)
+        self.assertIn("Did you mean: us", message)
+        self.assertIn("Short forms: jp", message)
+
+    def test_the_installer_says_the_same(self):
+        import importlib.util
+
+        spec = importlib.util.spec_from_file_location(
+            "install_under_test", Path(__file__).resolve().parents[1] / "install.py"
+        )
+        install = importlib.util.module_from_spec(spec)
+        spec.loader.exec_module(install)
+        with self.assertRaises(ValueError) as caught:
+            install.canonical_region("europ")
+        self.assertIn("Did you mean: europe", str(caught.exception))
+        self.assertIn("Short forms:", str(caught.exception))
+
+
 if __name__ == "__main__":
     unittest.main()