feat: rework validation schema options

cdxev/__main__.py

@@ -447,31 +447,22 @@ def create_validation_parser(
     group = parser.add_mutually_exclusive_group()
     group.add_argument(
         "--schema-type",
-        help=(
-            "Decide whether to use the default specification of CycloneDX or a custom schema. "
-            "The version will be derived from the specVersion in the provided SBOM. "
-            "If no version is provided defaults to 1.3."
-        ),
+        help="Use a built-in schema for validation.",
         choices=["default", "strict", "custom"],
-        default="default",
     )
     group.add_argument(
         "--schema-path",
         metavar="<schema-path>",
-        help=(
-            "Path to a JSON schema to use for validator. "
-            "If it's not specified, the program will try"
-            " to use one of the embedded schemata."
-        ),
-        type=str,
+        help="Path to the JSON schema file to validate against.",
+        type=Path,
     )
 
     group = parser.add_mutually_exclusive_group()
     group.add_argument(
         "--filename-pattern",
         help=(
             "Regex for validation of filename. If not specified, a default regex depending on "
-            "the schema-type is applied. To disable filename validation altogether, use "
+            "the schema is applied. To disable filename validation altogether, use "
             "--no-filename-validation."
         ),
         default="",
@@ -865,6 +856,12 @@ def invoke_validate(args: argparse.Namespace) -> int:
             args.parser,
         )
 
+    if args.schema_type is None and args.schema_path is None:
+        # Default to built-in stock schema. This case can't be handled by argparse
+        # due to an undocumented behavior which keeps options with default values
+        # from working correctly in mutually exclusive groups.
+        args.schema_type = "default"
+
     sbom, file_type = read_sbom(args.input)
     return (
         Status.OK