Add referrer to handler's call

jsonschema/tests/test_validators.py

@@ -1260,7 +1260,7 @@ def test_custom_uri_scheme_handlers(self):
         )
         with resolver.resolving(ref) as resolved:
             self.assertEqual(resolved, schema)
-        foo_handler.assert_called_once_with(ref)
+        foo_handler.assert_called_once_with(ref, referrer={})
 
     def test_cache_remote_on(self):
         ref = "foo://bar"
@@ -1272,7 +1272,7 @@ def test_cache_remote_on(self):
             pass
         with resolver.resolving(ref):
             pass
-        foo_handler.assert_called_once_with(ref)
+        foo_handler.assert_called_once_with(ref, referrer={})
 
     def test_cache_remote_off(self):
         ref = "foo://bar"
@@ -1302,6 +1302,36 @@ def test_helpful_error_message_on_failed_pop_scope(self):
             resolver.pop_scope()
         self.assertIn("Failed to pop the scope", str(exc.exception))
 
+    def test_scheme_default_fallback(self):
+        ref = './paths.json'
+        file_handler = mock.Mock()
+        resolver = validators.RefResolver(
+            "", "", handlers={"file": file_handler}
+        )
+        with resolver.resolving(ref):
+            pass
+        file_handler.assert_called_with(ref, referrer='')
+
+    def test_relative_resolver(self):
+        def file_handler(uri, referrer=None):
+            # Crude, do not use as a reference implementation
+            import os.path
+            no_scheme = referrer[7:]  # file:/// 0-based
+            return 'file://' + os.path.abspath(os.path.join(no_scheme, uri))
+
+        ref = '../../schemas/common.json'
+        base = 'file:///home/julian/spec/'
+        referrer = base + 'components/common.json'
+        expected = base + 'schemas/common.json'
+        resolver = validators.RefResolver(
+            "", referrer, handlers={"file": file_handler}
+        )
+        with resolver.resolving(ref):
+            pass
+
+        self.assertTrue(ref in resolver.store)
+        self.assertEqual(resolver.store[ref], expected)
+
 
 class UniqueTupleItemsMixin(object):
     """

jsonschema/validators.py

@@ -541,6 +541,8 @@ class RefResolver(object):
             Whether remote refs should be cached after first resolution
 
     """
+    default_scheme = 'file'
+    """ If urlsplit() does not find a scheme, we use this one. """
 
     def __init__(
         self,
@@ -739,9 +741,11 @@ def resolve_remote(self, uri):
             requests = None
 
         scheme = urlsplit(uri).scheme
+        if not scheme:
+            scheme = self.default_scheme
 
         if scheme in self.handlers:
-            result = self.handlers[scheme](uri)
+            result = self.handlers[scheme](uri, referrer=self.referrer)
         elif (
             scheme in [u"http", u"https"] and
             requests and