How do I take a screenshot when a test in internjs fails?

Question

I am having issues figuring out how to take a screenshot ONLY when a test fails in InternJs. I have this simple test in my registerSuite;

'verify google homepage': function () {
    var url = 'https://www.google.com/';
    return this.remote
        .get(url)
        .getCurrentUrl()
        .then(function (data) {
            assert.strictEqual(data, url, 'Incorrect URL');
        })
        .findByName('q')
            .click()
 }

I can simply create a screenshot using the following code;

.takeScreenshot
.then(function (data) {
    fs.writeFileSync('/path/to/some/file', data, 'base64');
)}

I want to only take a screenshot, if the above test fails the assertion or is unable to find the locator.

I looked into the afterEach method, but I can't figure out how to get the status of the last test to apply a conditional.

So my question is, has anyone setup their internjs test to only take screenshots on failures and how was it accomplished?

Answer 1

1. It is not currently possible to interact with the currently executing test from beforeEach or afterEach methods; this capability is coming in the next version of Intern.

2. Selenium server, by default, provides a screenshot on every Selenium command failure, which is a Buffer object on the error.detail.screen property. If a Selenium command fails, just use this property which already has the screenshot waiting for you.

3. For assertion failures, you can create a simple promise helper to take a screenshot for you:

function screenshotOnError(callback) {
  return function () {
    try {
      return callback.apply(this, arguments);
    }
    catch (error) {
      return this.remote.takeScreenshot().then(function (buffer) {
        fs.writeFileSync('/path/to/some/file', buffer);
        throw error;
      });
    }
  };
}

// ...

'verify google homepage': function () {
  return this.remote.get(url).getCurrentUrl().then(screenshotOnError(function (actualUrl) {
    assert.strictEqual(actualUrl, url);
  }));
}

If it’s too inconvenient to wrap all your callbacks manually like this, you can also create and use a custom interface for registering your tests that wraps the test functions automatically for you in a similar manner. I’ll leave that as an exercise for the reader.