Change error messages

Author: m-aciek

Lib/gettext.py

@@ -411,15 +411,15 @@ def _parse(self, fp):
                             self._charset = v.split('charset=')[1]
                         except IndexError:
                             raise ValueError(
-                                f"invalid content-type syntax in '{filename}': '{v}'. Expected 'charset='."
+                                f"expected 'charset=' in Content-Type metadata in {filename}, got {v!r}"
                             ) from None
                     elif k == 'plural-forms':
                         v = v.split(';')
                         try:
                             plural = v[1].split('plural=')[1]
                         except IndexError:
                             raise ValueError(
-                                f"invalid plural forms syntax in '{filename}': '{v}'. Expected ';' and 'plural='."
+                                f"expected ';' and 'plural=' in Plural-Forms metadata in {filename}, got {v!r}"
                             ) from None
                         self.plural = c2py(plural)
             # Note: we unconditionally convert both msgids and msgstrs to

Lib/test/test_gettext.py

@@ -675,7 +675,10 @@ def test_raise_descriptive_error_for_incorrect_content_type(self):
                 b'\x00\x00\x00\x00\x00\x008\x00\x00\x00(\x00\x00\x009\x00\x00\x00\x01\x00\x00\x00\x00\x00\x00\x00\x00'
                 b'\x00\x00\x00\x00Content-Type: text/plain; charste=UTF-8\n\x00'
             )
-        with self.assertRaisesRegex(ValueError, "invalid content-type syntax"):
+        with self.assertRaisesRegex(
+            ValueError,
+            "expected 'charset=' in Content-Type metadata in gettext.mo, got 'text/plain; charste=UTF-8'"
+        ):
             with open(MOFILE, 'rb') as fp:
                 gettext.GNUTranslations(fp)
 
@@ -691,7 +694,9 @@ def test_raise_descriptive_error_for_incorrect_plural_forms(self):
                 b'\x00\x00\x00\x00\x00\x008\x00\x00\x007\x00\x00\x009\x00\x00\x00\x01\x00\x00\x00\x00\x00\x00\x00\x00'
                 b'\x00\x00\x00\x00Content-Type: text/plain; charset=UTF-8\nPlural-Forms: \n\x00'
             )
-        with self.assertRaisesRegex(ValueError, "invalid plural forms syntax"):
+        with self.assertRaisesRegex(
+            ValueError, "expected ';' and 'plural=' in Plural-Forms metadata in gettext.mo, got ''"
+        ):
             with open(MOFILE, 'rb') as fp:
                 gettext.GNUTranslations(fp)