refFromServer.json

[
    {
        "description": "remote ref",
        "schema": {"$ref": "http://localhost:1234/integer.json"},
        "tests": [
            {
                "description": "remote ref valid",
                "data": 1,
                "valid": true
            },
            {
                "description": "remote ref invalid",
                "data": "a",
                "valid": false
            }
        ]
    },
    {
        "description": "fragment within remote ref",
        "schema": {"$ref": "http://localhost:1234/subSchemas.json#/integer"},
        "tests": [
            {
                "description": "remote fragment valid",
                "data": 1,
                "valid": true
            },
            {
                "description": "remote fragment invalid",
                "data": "a",
                "valid": false
            }
        ]
    },
    {
        "description": "ref within remote ref",
        "schema": {
            "$ref": "http://localhost:1234/subSchemas.json#/refToInteger"
        },
        "tests": [
            {
                "description": "ref within ref valid",
                "data": 1,
                "valid": true
            },
            {
                "description": "ref within ref invalid",
                "data": "a",
                "valid": false
            }
        ]
    },
    {
        "description": "change resolution scope",
        "schema": {
            "items": {
                "id": "folder/",
                "anyOf": [{"$ref": "folderInteger.json"}]
            }
        },
        "tests": [
            {
                "description": "changed scope ref valid",
                "data": [1],
                "valid": true
            },
            {
                "description": "changed scope ref invalid",
                "data": ["a"],
                "valid": false
            }
        ]
    }
]

schemasToServe.json

{
    "integer.json": {"type": "integer"},
    "subSchemas.json": {
        "integer": {"type": "integer"},
        "refToInteger": {"$ref": "#/integer"}
    },
    "folder/folderInteger.json": {"type": "integer"}
}

serve.py

from flask import Flask, jsonify
app = Flask(__name__)

schemas_to_serve = json.load('schemasToServe.json')
for url, schema in schemas_to_serve:
    app.route(url)(lambda: jsonify(schema))
    
app.run()