observableMatcher.ts

import * as _ from 'lodash';
import * as chai from 'chai';

function stringify(x: any): string {
  return JSON.stringify(x, function (key: string, value: any) {
    if (Array.isArray(value)) {
      return '[' + value
        .map(function (i) {
          return '\n\t' + stringify(i);
        }) + '\n]';
    }
    return value;
  })
  .replace(/\\"/g, '"')
  .replace(/\\t/g, '\t')
  .replace(/\\n/g, '\n');
}

function deleteErrorNotificationStack(marble: any) {
  const { notification } = marble;
  if (notification) {
    const { kind, error } = notification;
    if (kind === 'E' && error instanceof Error) {
      notification.error = { name: error.name, message: error.message };
    }
  }
  return marble;
}

export function observableMatcher(actual: any, expected: any) {
  if (Array.isArray(actual) && Array.isArray(expected)) {
    actual = actual.map(deleteErrorNotificationStack);
    expected = expected.map(deleteErrorNotificationStack);
    const passed = _.isEqual(actual, expected);
    if (passed) {
      return;
    }

    let message = '\nExpected \n';
    actual.forEach((x: any) => message += `\t${stringify(x)}\n`);

    message += '\t\nto deep equal \n';
    expected.forEach((x: any) => message += `\t${stringify(x)}\n`);

    chai.assert(passed, message);
  } else {
    chai.assert.deepEqual(actual, expected);
  }
}