openethereum/js/src/environment/integration-tests/fake-backend.js

// Copyright 2015, 2016 Ethcore (UK) Ltd.
// This file is part of Parity.

// Parity is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// Parity is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with Parity.  If not, see <http://www.gnu.org/licenses/>.

import sinon from 'sinon/pkg/sinon';
import mockedResponses from '../../../test/mocked-responses.json';

class FakeRpcServer {
  constructor () {
    this.xhr = null;
    this.middlewares = [];
  }

  start () {
    this.xhr = sinon.useFakeXMLHttpRequest();
    this.xhr.onCreate = this.handleRequest;
    return () => this.xhr.restore();
  }

  simpleRpc (rpcMethod, result) {
    this.rpc(rpcMethod, req => result);
  }

  rpc (rpcMethod, middleware) {
    this.middlewares.unshift({
      rpcMethod, middleware
    });
  }

  handleRequest = req => {
    setTimeout(() => {
      req.body = JSON.parse(req.requestBody);
      const middlewaresForMethod = this.middlewares
        .filter(m => m.rpcMethod === req.body.method);

      const response = middlewaresForMethod
        .map(m => m.middleware)
        .reduce((replied, middleware) => {
          if (replied) {
            return replied;
          }

          return middleware(req);
        }, false);

      if (!response) {
        return req.respond(405, {
          'Content-Type': 'application/json'
        }, JSON.stringify({
          jsonrpc: '2.0',
          id: req.body.id,
          result: null
        }));
      }

      return req.respond(200, {
        'Content-Type': 'application/json'
      }, JSON.stringify({
        jsonrpc: '2.0',
        id: req.body.id,
        result: response
      }));
    });
  }
}

const fakeRpc = new FakeRpcServer();
fakeRpc.start();
mockedResponses.rpc.forEach(method => fakeRpc.simpleRpc(method.name, method.response));

// export fakeRpc to mock stuff in tests
window.fakeRpc = fakeRpc;