add draft 2019-09 -> draft 7 test

Author: gregsdennis

remotes/draft7/ignore-dependentRequired.json

@@ -0,0 +1,7 @@
+{
+    "$id": "http://localhost:1234/draft7/integer.json",
+    "$schema": "http://json-schema.org/draft-07/schema#",
+    "dependentRequired": {
+        "foo": ["bar"]
+    }
+}

tests/draft2019-09/optional/cross-draft.json

@@ -19,5 +19,23 @@
                 "valid": true
             }
         ]
+    },
+    {
+        "description": "refs to historic drafts are processed as historic drafts",
+        "schema": {
+            "type": "object",
+            "allOf": [
+                { "properties": { "foo": true } },
+                { "$ref": "http://localhost:1234/draft7/ignore-dependentRequired.json" }
+            ]
+        },
+        "tests": [
+            {
+                "description": "missing bar is valid",
+                "$comment": "if the implementation is not processing the $ref as a draft 7 schema, this test will fail",
+                "data": {"foo": "any value"},
+                "valid": true
+            }
+        ]
     }
 ]