Using JSON API with WebdriverIO Tests

In Drupal, you can write automated tests with different levels of complexity. If you need to test a single function, or method of a class, probably you will be fine with a unit test. When you need to interact with the database, you can create kernel tests. And finally, if you need access to the final HTML rendered by the browser, or play with some javascript, you can use functional tests or Javascript tests. You can read more about this in the Drupal.org documentation.

So far this is what Drupal provides out of the box. On top of that, you can use Behat or WebDriver tests. This types of tests are usually easier to write and are closer to the user needs. As a side point, they are usually slower than the previous methods.

The Problem.

In Gizra, we use WebdriverIO for most of our tests. This allow us to tests useful things that add value to our clients. But these sort of tests, where you only interact with the browser output, has some disadvantages.

Imagine you want to create an article and check that this node is unpublished by default. How do you check this? Remember you only have the browser output…

One possible way could be this: Login, visit the Article creation form, fill the fields, click submit, and then… Maybe search for some unpublished class in the html:

    var assert = require('assert');

    describe('create article', function() {
        it('should be possible to create articles, unpublished by default', function() {
            browser.loginAs('some user');

            browser.url('http://example.com/node/add/article')
            browser.setValueSafe('#edit-title-0-value', 'My new article');
            browser.setWysiwygValue('edit-body-0-value', 'My new article body text');

            browser.click('#edit-submit');

            browser.waitForVisible('.node-unpublished');
        });
    });

This is quite simple to understand, but it has some drawbacks.

For one, it depends on the theme to get the status of the node. You could take another approach and instead of looking for a .node-unpublished class, you could logout from the current session and then try to visit the url to look for an access denied legend.

Getting Low-Level Information from a Browser Test

So the problem boils down to this:

How can I get information about internal properties from a browser test?

The new age of decoupled Drupal brings an answer to this question. It could be a bit counterintuitive at first, therefore just try to see is fit for your project.

The idea is to use the new modules that expose Drupal internals, through json endpoints, and use javascript together with a high-level testing framework to get the info you need.

In Gizra we use WDIO tests write end-to-end tests. We have some articles about this topic. We also wrote about a new module called JsonAPI that exposes all the information you need to enrich your tests.

The previous test could be rewritten into a different test. By making use of the JsonAPI module, you can get the status of a specific node by parsing a JSON document:

var assert = require('assert');

describe('create article', function() {
    it('should be possible to create articles, unpublished by default', function() {
        browser.loginAs('some user');

        browser.url('http://example.com/node/add/article')
        browser.setValueSafe('#edit-title-0-value', 'My unique title');
        browser.setWysiwygValue('edit-body-0-value', 'My new article body text');

        browser.click('#edit-submit');

        // Use JSON api to get the internal data of a node.
        let query = '/jsonapi/node/article'
                 += '?fields[node--article]=status'
                 += '&filter[status]=0'
                 += '&filter[node-title][condition][path]=title'
                 += '&filter[node-title][condition][value]=My unique title'
                 += '&filter[node-title][condition][operator]=CONTAINS'

        browser.url(query);
        browser.waitForVisible('body pre');
        let json = JSON.parse(browser.getHTML('body pre', false));

        assert.ok(json[0].id);
        assert.equals(false, json[0].attributes.content['status']);
    });
});

In case you skipped the code, don’t worry, it’s quite simple to understand, let’s analyze it:

1. Create the node as usual:

This is the same as before:

browser.url('http://example.com/node/add/article')
browser.setValueSafe('#edit-title-0-value', 'My unique title');
browser.setWysiwygValue('edit-body-0-value', 'My new article body text');

browser.click('#edit-submit');

2. Ask JsonAPI for the status of an article with a specific title:

Here you see the two parts of the request and the parsing of the data.

let query = '/jsonapi/node/article'
            += '?fields[node--article]=status'
            += '&filter[status]=0'
            += '&filter[node-title][condition][path]=title'
            += '&filter[node-title][condition][value]=My unique title'
            += '&filter[node-title][condition][operator]=CONTAINS'

browser.url(query);

3. Make assertions based on the data:

Since JsonAPI exposes, well, json data, you can convert the json into a javascript object and then use the dot notation to access to a specific level.

This is how you can identify a section of a json document.
browser.waitForVisible('body pre');
let json = JSON.parse(browser.getHTML('body pre', false));
assert.ok(json[0].id);
assert.equals(false, json[0].attributes.content['status']);

A Few Enhancements

As you can see, you can parse the output of a json request directly from the browser.

browser.url('/jsonapi/node/article');
browser.waitForVisible('body pre');
let json = JSON.parse(browser.getHTML('body pre', false));

The json object now contains the entire response from JsonAPI that you can use as part of your test.

There are some drawbacks of the previous approach. First, this only works for Chrome. That includes the Json response inside a XML document. This is the reason why you need to get the HTML from body pre.

The other problem is this somewhat cryptic section:

let query = '/jsonapi/node/article'
        += '?fields[node--article]=status'
        += '&filter[status]=0'
        += '&filter[node-title][condition][path]=title'
        += '&filter[node-title][condition][value]=My unique title'
        += '&filter[node-title][condition][operator]=CONTAINS'

The first problem can be fixed using a conditional to check which type of browser are you using to run the tests.

The second problem can be addressed using the d8-jsonapi-querystring package, that allows you to write an object that is automatically converted into a query string.

Other Use Cases

So far, we used JsonAPI to get information about a node. But there are other things that you can get from this API. Since all configurations are exposed, you could check if some role have some specific permission. To make tests shorter we skipped the describe and it sections.

browser.loginAs('some user');

let query = '/jsonapi/user_role/user_role'
         += '?filter[is_admin]=null'

browser.url(query);
browser.waitForVisible('body pre');
let json = JSON.parse(browser.getHTML('body pre', false));

json.forEach(function(role) {
    assert.ok(role.attributes.permissions.indexOf("bypass node access") == -1);
});

Or if a field is available in some content type, but it is hidden to the end user:

browser.loginAs('some user');

let query = '/jsonapi/entity_form_display/entity_form_display?filter[bundle]=article'

browser.url(query);
browser.waitForVisible('body pre');
let json = JSON.parse(browser.getHTML('body pre', false));

assert.ok(json[0].attributes.hidden.field_country);

Or if some specific HTML tag is allowed in an input format:

let query = '/jsonapi/filter_format/filter_format?filter[format]=filtered_html'

browser.url(query);
browser.waitForVisible('body pre');
let json = JSON.parse(browser.getHTML('body pre', false));

let tag = '<drupal-entity data-*>';

assert.ok(json[0].attributes.filters.filter_html.settings.allowed_html.indexOf(tag) > -1);

As you can see, there are several use cases. The benefits of being able to explore the API by just clicking the different links sometimes make this much easier to write than a kernel test.

Just remember that this type of tests are a bit slower to run, since they require a full Drupal instance running. But if you have some continuous integration in place, it could be an interesting approach to try. At least for some specific tests.

We have found this quite useful, for example, to check that a node can be referenced by another in a reference field. To check this, you need the node ids of all the nodes created by the tests.

A tweet by @skyredwang could be accurate to close this post.

mariano's profile

Mariano D'Agostino

@dagmar