Preserve extensions in the translation from JSON schema to OpenAPI (#994

)

dropshot/src/schema_util.rs

@@ -488,6 +488,14 @@ fn j2oas_schema_object(
         data.write_only = metadata.write_only;
     }
 
+    // Preserve extensions
+    data.extensions = obj
+        .extensions
+        .iter()
+        .filter(|(key, _)| key.starts_with("x-"))
+        .map(|(key, value)| (key.clone(), value.clone()))
+        .collect();
+
     if let Some(name) = name {
         data.title = Some(name.clone());
     }
@@ -1069,4 +1077,21 @@ mod test {
 
         let _ = j2oas_schema_object(None, &schema);
     }
+
+    #[test]
+    fn test_extension_conversion() {
+        let j = serde_json::json!({
+            "type": "object",
+            "x-stuff": {
+                "a": "b",
+                "c": [ "d", "e" ]
+            }
+        });
+
+        let pre: schemars::schema::Schema =
+            serde_json::from_value(j.clone()).unwrap();
+        let post = j2oas_schema(None, &pre);
+        let v = serde_json::to_value(post.as_item().unwrap()).unwrap();
+        assert_eq!(j, v);
+    }
 }