Fix issue #669 and add test case.

jsonschema/cli.py

@@ -7,6 +7,7 @@
 import argparse
 import errno
 import json
+import os
 import sys
 import traceback
 
@@ -15,7 +16,7 @@
 from jsonschema import __version__
 from jsonschema._reflect import namedAny
 from jsonschema.exceptions import SchemaError
-from jsonschema.validators import validator_for
+from jsonschema.validators import validator_for, RefResolver
 
 
 class _CannotLoadFile(Exception):
@@ -178,6 +179,15 @@ def _namedAnyWithDefault(name):
         of the class.
     """,
 )
+parser.add_argument(
+    "--base-uri",
+    action="store_true",
+    help="""
+        use this option to indicate that the schema contains some references
+        to some local files. With this option, the validator will try to
+        resolve those references as paths relative to the given schema.
+    """,
+)
 parser.add_argument(
     "--version",
     action="version",
@@ -251,7 +261,16 @@ def load(_):
                 raise _CannotLoadFile()
         instances = ["<stdin>"]
 
-    validator = arguments["validator"](schema)
+    if arguments["base_uri"]:
+        file_prefix = "file:///{}/" if "nt" == os.name else "file://{}/"
+        schema_dirname = os.path.dirname(arguments["schema"])
+        resolver = RefResolver(
+            base_uri=file_prefix.format(os.path.abspath(schema_dirname)),
+            referrer=schema,
+        )
+    else:
+        resolver = None
+    validator = arguments["validator"](schema, resolver=resolver)
     exit_code = 0
     for each in instances:
         try:

jsonschema/tests/test_cli.py

@@ -683,6 +683,23 @@ def test_successful_validation__of_just_the_schema_pretty_output(self):
             stderr="",
         )
 
+    def test_successful_validation_with_specifying_base_uri(self):
+        schema = """\
+                {"type": "object", "properties": {"KEY1":
+                {"$ref": "schema.json#definitions/schemas"}},
+                "definitions": {"schemas": {"type": "string"}}}
+                """
+        fp = open("schema.json", "w+")
+        fp.write(schema)
+        fp.close()
+        self.assertOutputs(
+            files=dict(some_schema=schema, some_instance='{"KEY1": "1"}'),
+            argv=["-i", "some_instance", "--base-uri", "some_schema"],
+            stdout="",
+            stderr="",
+        )
+        os.remove("schema.json")
+
     def test_real_validator(self):
         self.assertOutputs(
             files=dict(some_schema='{"minimum": 30}', some_instance="37"),