Use data-test tag for the business testing

We are going to use a special tag data-test for the purpose of integration testing, especially for the business purpose.

What is this tag?

Let’s see with an example:

<button data-test="logout">Logout<button>

The usage is pretty simple, just apply data-test tag to any DOM element you want.

Why do we need another tag? Do we have id, class, role, and more?

Business semantic

I was told by our testing engineer the tag is introduced for the semantic purpose, however in the end of the conversation, I’m pretty sure his semantics is not perfectly align with what I understand as the DOM semantics. Let’s hear out his version.

As long as there’s a logout button on the screen, attaching a logout key should provide us a way to consistently to locate it. Moreover, if the developer decides to use a div instead:

<div data-test="logout">Logout</div>

We should still be able to locate it, since the test were coded with the data-test tag instead of the element type. Of course, this tag data-test is agreed upon by the team; because we can also use id or class for this example.

Can we uniquely define an element with data-test ? The answer is no. Not only we can’t, but also that’s not the goal. Let’s take a look at the table to better understand this tag:

<table data-test="personList">
<tr data-test="person">
<td data-test="firstName">
...
</td>
</tr>
</table>

To find the first person’s first name in the table, we will find the “personList”, and then look at the first “person”, and then the first column “firstName” is the one we are looking for.

Notice the sentence doesn’t involve element words such as table`, tr and td; and doesn’t involve table semantic words such as row and column ; instead it used person and firstName as well as the personList .

Find the person list, get the first person, and find his first name.

It’s pretty obvious now, the data-test isn’t created for uniqueness, but more like what a role is.

Now comes the benefits, in case we change the table implementation into a list:

<ul data-test="personList">
<li data-test="item">
<span data-test="firstName">
...
</span>
</li>
</li>

The test can run without much modification if any. Because we still want to “find the personal list, get the first person, and find his first name”. I guess I can conclude this as what he meant by business semantics.

Summary

A data-test tag is introduced for testing the business semantics. This could potentially make testing more productive especially when the project grows bigger.

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Fang Jin

Fang Jin

Front-end Engineer, book author of “Designing React Hooks the Right Way” sold at Amazon. On my part time, I’d like to share my view in current economics.