使用测试全局变量

Nightwatch 提供的另一个有用概念是测试全局变量。最简单的形式，它是在配置文件中定义的键值对字典。

全局变量可以定义为 "globals" 属性，也可以定义为外部文件，该文件指定为 "globals_path" 属性。

以下是使用 nightwatch.json 中的 "globals" 属性的示例定义。

nightwatch.conf.js 
{
  "src_folders": [],

  "globals": {
    "myGlobalVar" : "some value",
    "otherGlobal" : "some other value"
  },

  "test_settings": {
    "default": {
      "launch_url": "https://nightwatch.node.org.cn",
    }
  }
}

与 launch_url 属性类似，globals 对象直接在传递给测试的 Nightwatch api 上可用。

tests/sampleTest.js 
module.exports = {
  'Demo test' : function (browser) {
    console.log(browser.globals.myGlobalVar); // myGlobalVar == "some value"
  }
};

预定义全局变量

以下全局属性可用于控制测试运行器的行为，并使用以下默认值定义。

nightwatch/globals.js 
module.exports = {
  // this controls whether to abort the test execution when an assertion failed and skip the rest
  // it's being used in waitFor commands and expect assertions
  abortOnAssertionFailure: true,

  // this will overwrite the default polling interval (currently 500ms) for waitFor commands
  // and expect assertions that use retry
  waitForConditionPollInterval: 500,

  // default timeout value in milliseconds for waitFor commands and implicit waitFor value for
  // expect assertions
  waitForConditionTimeout : 5000,

  // since 1.4.0 – this controls whether to abort the test execution when an element cannot be located; an error
  // is logged in all cases, but this also enables skipping the rest of the testcase;
  // it's being used in element commands such as .click() or .getText()
  abortOnElementLocateError: false,
  
  // this will cause waitFor commands on elements to throw an error if multiple
  // elements are found using the given locate strategy and selector
  throwOnMultipleElementsReturned: false,

  // By default a warning is printed if multiple elements are found using the given locate strategy
  // and selector; set this to true to suppress those warnings
  suppressWarningsOnMultipleElementsReturned: false,

  // controls the timeout value for async hooks. Expects the done() callback to be invoked within this time
  // or an error is thrown
  asyncHookTimeout : 10000,

  // controls the timeout value for when running async unit tests. Expects the done() callback to be invoked within this time
  // or an error is thrown
  unitTestsTimeout : 2000,

  // controls the timeout value for when executing the global async reporter. Expects the done() callback to be 
  // invoked within this time or an error is thrown
  customReporterCallbackTimeout: 20000,

  // Automatically retrying failed assertions - You can tell Nightwatch to automatically retry failed assertions 
  // until a given timeout is reached, before the test runner gives up and fails the test.
  retryAssertionTimeout: 5000,

  // Custom reporter
  reporter: function(results, done) {
    // do something with the results
    done(results);
  }
}

环境特定全局变量

与其他测试设置类似，全局变量可以被每个测试环境覆盖。考虑以下配置。

nightwatch.json 
{
  "src_folders": [],

  "test_settings": {
    "default": {
      "launch_url": "https://nightwatch.node.org.cn",

      "globals": {
        "myGlobalVar" : "some value",
        "otherGlobal" : "some other value"
      }
    },

    "integration": {
      "globals": {
        "myGlobalVar" : "integrated global"
      }
    }
  }
}

如果我们仍然将 --env integration 选项传递给运行器，那么我们的全局变量对象将如下所示。

nightwatch --env integration
module.exports = {
  'Demo test' : function (browser) {
    console.log(browser.globals.myGlobalVar); // myGlobalVar == "integrated global"
  }
};