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 +179,14 @@ def _namedAnyWithDefault(name):
         of the class.
     """,
 )
+parser.add_argument(
+    "--base-uri",
+    help="""
+        use this option to indicate that the schema contains some references
+        to some local or remote 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 +260,24 @@ def load(_):
                 raise _CannotLoadFile()
         instances = ["<stdin>"]
 
-    validator = arguments["validator"](schema)
+    if arguments["base_uri"] is None:
+        resolver = None
+    elif "http:" in arguments["base_uri"] or "https:" in arguments["base_uri"]\
+            or "urn:" in arguments["base_uri"]:
+        resolver = RefResolver(
+            base_uri=arguments["base_uri"],
+            referrer=schema,
+        )
+    else:
+        file_prefix = "file:///{}/" if "nt" == os.name else "file://{}/"
+        resolver = RefResolver(
+            base_uri=file_prefix.format(
+                os.path.abspath(arguments["base_uri"])
+            ),
+            referrer=schema,
+        )
+
+    validator = arguments["validator"](schema, resolver=resolver)
     exit_code = 0
     for each in instances:
         try:

jsonschema/tests/test_cli.py

@@ -7,6 +7,7 @@
 import os
 import subprocess
 import sys
+import tempfile
 
 from jsonschema import Draft4Validator, cli, __version__
 from jsonschema.exceptions import SchemaError, ValidationError
@@ -683,6 +684,32 @@ def test_successful_validation__of_just_the_schema_pretty_output(self):
             stderr="",
         )
 
+    def test_successful_validation_with_specifying_base_uri(self):
+        try:
+            schema_file = tempfile.NamedTemporaryFile(
+                mode='w+',
+                prefix='schema',
+                suffix='.json',
+                dir='..',
+                delete=False
+            )
+            self.addCleanup(os.remove, schema_file.name)
+            schema = """
+                    {"type": "object", "properties": {"KEY1":
+                    {"$ref": %s%s#definitions/schemas"}},
+                    "definitions": {"schemas": {"type": "string"}}}
+                    """ % ("\"", os.path.basename(schema_file.name))
+            schema_file.write(schema)
+        finally:
+            schema_file.close()
+
+        self.assertOutputs(
+            files=dict(some_schema=schema, some_instance='{"KEY1": "1"}'),
+            argv=["-i", "some_instance", "--base-uri", "..", "some_schema"],
+            stdout="",
+            stderr="",
+        )
+
     def test_real_validator(self):
         self.assertOutputs(
             files=dict(some_schema='{"minimum": 30}', some_instance="37"),