Ignore $ref siblings in supported JSON Schema drafts

src/hypothesis_jsonschema/_resolve.py

@@ -25,7 +25,6 @@
     HypothesisRefResolutionError,
     Schema,
     canonicalish,
-    merged,
 )
 
 
@@ -57,15 +56,9 @@ def resolve_all_refs(
         )
 
     if "$ref" in schema:
-        s = dict(schema)
-        ref = s.pop("$ref")
-        with resolver.resolving(ref) as got:
-            m = merged([s, resolve_all_refs(got, resolver=resolver)])
-            if m is None:  # pragma: no cover
-                msg = f"$ref:{ref!r} had incompatible base schema {s!r}"
-                raise HypothesisRefResolutionError(msg)
-            assert "$ref" not in m
-            return m
+        # All supported drafts (04, 06, 07) ignore siblings of $ref.
+        with resolver.resolving(schema["$ref"]) as got:
+            return resolve_all_refs(got, resolver=resolver)
     assert "$ref" not in schema
 
     for key in SCHEMA_KEYS:

tests/corpus-suite-schemas.json

@@ -1729,6 +1729,7 @@
             "propertyNames": true
         },
         "draft7/ref overrides any sibling keywords": {
+            "$schema": "http://json-schema.org/draft-07/schema#",
             "definitions": {
                 "reffed": {
                     "type": "array"

tests/test_from_schema.py

@@ -108,6 +108,46 @@ def test_can_generate_with_explicit_schema_version(_):
     pass
 
 
+@pytest.mark.parametrize("draft", ["04", "06", "07"])
+@pytest.mark.parametrize("definition_key", ["definitions", "$defs"])
+@settings(deadline=None)
+@given(data=st.data())
+def test_ref_siblings_do_not_resolve_against_a_subschema(data, draft, definition_key):
+    # GH-97: items is a sibling of $ref, and must not be resolved or applied.
+    ref = f"#/{definition_key}/foo"
+    schema = {
+        "$schema": f"http://json-schema.org/draft-{draft}/schema#",
+        definition_key: {
+            "foo": {
+                "properties": {"foo": {"type": "string"}},
+                "additionalProperties": False,
+            },
+        },
+        "type": "object",
+        "properties": {
+            "bar": {
+                "$ref": ref,
+                "type": ["object", "array"],
+                "items": {"type": "object", "$ref": ref},
+            },
+        },
+    }
+    value = data.draw(from_schema(schema))
+    jsonschema.validate(value, schema)
+
+
+@pytest.mark.parametrize("draft", ["04", "06", "07"])
+@given(data=st.data())
+def test_ref_ignores_conflicting_sibling_constraints(data, draft):
+    schema = {
+        "$schema": f"http://json-schema.org/draft-{draft}/schema#",
+        "definitions": {"value": {"enum": ["hello"]}},
+        "$ref": "#/definitions/value",
+        "type": "integer",
+    }
+    assert data.draw(from_schema(schema)) == "hello"
+
+
 INVALID_SCHEMAS = {
     # Empty list for requires, which is invalid
     "Release Drafter configuration file",