→ How Canaries Help Us Merge Good Pull Requests

I recently published an article on the WordPress.com Developer’s Blog about how we run automated canary tests on pull requests to give us confidence to release frequent changes without breaking things. Feel free to check it out.

AMA: Difference between explicit and fluent wait

Anonymous asks…

What is the difference between Explicit wait and Fluent wait?

My response…

I hadn’t heard of fluent waiting before, only explicit and implicit waiting.

From my post about Waiting in C# WebDriver:

Implicit Waiting

Implicit, or implied waiting involves setting a configuration timeout on the driver object where it will automatically wait up to this amount of time before throwing a NoSuchElementException.

The benefit of implicit waiting is that you don’t need to write code in multiple places to wait as it does it automatically for you.

The downsides to implicit waiting include unnecessary waiting when doing negative existence assertions and having tests that are slow to fail when a true failure occurs (opposite of ‘fail fast’).

Explicit Waiting

Explicit waiting involves putting explicit waiting code in your tests in areas where you know that it will take some time for an element to appear/disappear or change.

The most basic form of explicit waiting is putting a sleep statement in your WebDriver code. This should be avoided at all costs as it will always sleep and easily blow out test execution times.

WebDriver provides a WebDriverWait class which allows you to wait for an element in your code.

As for fluent waits, according to this page it’s a type of explicit wait with more limited conditions on it. I don’t believe WebDriverJs supports fluent waits.

AMA: Moving automated tests from Java to JavaScript

Anonymous asks…

I am currently using a BDD framework with Cucumber, Selenium and Java for automating a web application. I used page factory to store the objects and using them in java methods I wanted to replace the java piece of code with javaScript like mocha or webdriverio. could you share your thoughts on this? can I still use page factory to maintain objects and use them in js files

My response…

What’s the reasoning for moving to JavaScript from Java? Despite having common names, there’s very little otherwise in common (Car is to Carpet as Java is to JavaScript.)

I wouldn’t move for moving sake since I see no benefit in writing BDD style web tests in JavaScript, if anything, e2e automated tests are much harder to write in JavaScript/Node because everything is asynchronous and so you have to deal with promises etc. which is much harder to do than just using Java (or Ruby).

Aside: I still dream of writing e2e tests in Ruby: it’s just so pleasant. But our new user interface is written extensively in JavaScript (React) so it makes sense from a sustainability point of view to use JS over Ruby.

 

Why you should use CSS selectors for your WebDriver tests

I didn’t used to be a fan of CSS selectors for automated web tests, but I changed my mind.

The reason I didn’t use to be a fan of CSS selectors is that historically they weren’t really encouraged by Watir, since the Watir API was designed to find elements by type and attribute, so the Watir API would look something like:

browser.div(:class => 'highlighted')

where the same CSS selector would look like:

div.highlighted

Since WebDriver doesn’t use the same element type/attribute API and just uses findElement with a By selector, CSS selectors make the most sense since they’re powerful and self-contained.

The the best thing about using CSS selectors, in my opinion, is the Chrome Dev Tools allows you to search the DOM using a CSS selector (and XPath selectors, but please don’t use XPath), using Command/Control & F:

chrome css selectors
Using CSS selectors to find elements in Chrome Dev Tools

So you can ‘test’ your CSS in a live browser window before deciding to use it in your WebDriver test.

The downside of using CSS selectors are they’re a bit less self explanatory than explicitly using by.className or by.id.

But CSS selectors are pretty powerful: especially pseudo selectors like nth-of-type and I’ve found the only thing you can’t really do in CSS is select by text value, which you probably shouldn’t be doing anyway as text values are more likely to change (since they’re copy often changed by your business) and can be localised in which case your tests won’t run across different cultures.

The most powerful usage of CSS selectors is where you add your own data attributes to elements in your application and use these to select elements: straightforward, efficient and less brittle than other approaches. For example:

a[data-e2e-value="free"]

How do you identify elements in your WebDriver automated tests?

AMA: Trunk Guardian Service?

Sue asks…

I read a LinkedIn blog post from 2015 by Keqiu Hu from LinkedIn about flaky UI tests. He explains how they fixed their flaky UI tests for the LinkedIn app. Among other things they implemented what they called the “Trunk Guardian service” which runs automated UI tests on the last known good build twice and if the test passes on the first run but fails on the second it is marked as ‘flaky’ and disabled and the owner is notified to fix it or get rid of it. I wondered what your thoughts were on such a “Trunk Guardian service” – if the culture / process was in place to solve the other issues that create flaky tests, could such a thing be worth the effort to implement? Article: Test Stability – How We Make UI Tests Stable

My response…

Continue reading “AMA: Trunk Guardian Service?”

AMA: IE11 Button Clicking in Selenium

Anthony asks…

I have coded to click buttons on IE11/Win7 but the latest version of Selenium IE doesn’t click the buttons correctly most of times. Most of times, it clicks one button below. I thought it might be loading time so added some waiting but still click one button below or two buttons below sometimes. I googled this and found several posting saying Selenium IE doesn’t click buttons well. Now I have moved it to FF but I am still wondering why IE is not accurate. I know a lot of Selenium test developers in the field but they are having the same issue or they know a workaround. What do you think of this issue on IE11? Are you aware of this issue? FYI, the buttons are not regular HTML tag. The menu system with clickable tag is created by javascript. Thank you!

My Response…

We actually don’t run any tests in Internet Explorer any more since these weren’t finding any browser specific bugs (we do exploratory testing in Internet Explorer instead).

But, I have heard of problems generally with the IEDriver tool. If you’re working on a JavaScript generated app I think the best thing for you to do would instead of using a native click in Selenium is instead execute a JavaScript click event. The exact syntax will depend on which language you’re using Selenium in, but it should look something like this:

this.driver.executeScript( 'return arguments[0].click();', webElement );

I hope this solution helps!

AMA: CodeceptJS support for Safari and IE?

Sahana Asks…

We area VOD startup and we have web app, mobile apps and TV apps. I am writing acceptance tests for web app now and chose codeceptjs framework since we have our website’s front end code in Javascript. We have dockerised the processes and docker images for codeceptjs webdriver IO is availble only for chrome and firefox browsers. How can I handle Safari , Internet Explorer browsers ? Looks like CodeceptJs does not support IE and Safari browsers. Do you have any suggestion?

My Response…

I’ve never personally found the return on investment of getting automated tests running across Internet Explorer and  Safari to be worthwhile as in my experience this took more effort than the bugs it found. So I personally stick to running our full e2e test suite in our most used browser (Chrome) and supplementing this with exploratory testing on all other browsers.

In saying that the reason you won’t be able to use Docker containers for these purposes is that they’re Linux and Internet Explorer requires Microsoft Windows and Safari requires Apple macOS to be able to run. To be able to use these for your existing automated tests you can sign up to a on-demand browser service like SauceLabs and use the remote WebDriver protocol to execute your tests.