Testing environment

Before reading this article we recommend getting familiar with the CKEditor 5 development environment.

# Introduction

The CKEditor 5 testing environment uses a popular setup with Karma, webpack, babel-loader and Istanbul. We created some npm scripts which glue all these pieces and special requirements for CKEditor together.

Each CKEditor 5 package has its own tests suite (see for example the engine’s tests), however, the test runner is available in the root of the ckeditor5 repository which is the central development environment. The actual code of the test runner is implemented in the @ckeditor/ckeditor5-dev-tests package and can be easily reused outside of ckeditor5.

# Running automated tests

In order to run the automated tests, use the yarn run test [<args>...] command.

It accepts the following arguments that must be passed after the -- option:

• --watch (alias -w) – Whether to watch the files and execute tests whenever any file changes.
• --source-map (alias -s) – Whether to generate useful source maps for the code.
• --coverage (alias -c) – Whether to generate code coverage.
• --verbose (alias -v) – Allows switching on webpack logs.
• --files – Specifies test files to run. Accepts a package name or a glob. For example --files=engine will run tests from ckeditor5-engine package. Read more about the rules for converting the --files option to a glob pattern.
• --browsers – Browsers that will be used to run the tests. Defaults to Chrome.
• --debug (alias -d) – Allows specifying custom debug flags. For example, the --debug engine option uncomments the // @if CK_DEBUG_ENGINE // lines in the code. Note that by default --debug is set to true even if you did not specify it. This enables the base set of debug logs (// @if CK_DEBUG //) which should always be enabled in the testing environment. You can completely turn off the debug mode by setting the --debug false option.
• --port – Specifies the port for the server to use. Defaults to 9876.
• --identity-file="/path/to/file.js" (alias -i) – Path to the file containing the license key(s) for closed–source features.

# Examples

Run all tests with the code coverage check of the ckeditor5-core package:

yarn run test -c --files=core

Run and watch the engine’s view namespace tests and all the tests in ckeditor5-typing:

yarn run test -cw --files=engine/view,typing

Run the bold*.js tests in the ckeditor5-basic-styles package:

yarn run test -cw --files=basic-styles/bold*.js

# Custom Chai assertions

Our testing environment allows for some custom Chai assertions. There is no need to import them, as they are imported by default inside all tests.

# equalMarkup

Tests whether two given strings containing markup language are equal. Unlike expect().to.equal() from Chai assertion library, this assertion formats the markup before showing a diff. It can be used to test HTML strings and strings containing a serialized model.

This assertion will pass:

expect( `<b>foo</b>` ).to.equalMarkup( `<b>foo</b>` )

This assertion will throw an error:

expect(
    '<paragraph>foo bXXX[]r baz</paragraph>'
).to.equalMarkup(
    '<paragraph>foo bYYY[]r baz</paragraph>'
);

# attribute

Asserts that the target has an attribute with the given key name. See hasAttribute.

expect( selection ).to.have.attribute( 'linkHref' );

When optional value is provided, .attribute also asserts that the attribute’s value is equal to the given value. See getAttribute.

expect( selection ).to.have.attribute( 'linkHref', 'example.com' );

Negations works as well.

expect( selection ).to.not.have.attribute( 'linkHref' );

# Running manual tests

In order to start the manual tests server, use the yarn run manual task.

The task accepts the following options:

• --files (alias -f) – Specifies test files to run. Accepts a package name or a glob. For example --files=ckeditor5 will only run tests from the CKEditor 5 main package. Read more about the rules for converting the --files option to a glob pattern.
• --language="pl" – The main language build in into all test editors, passed to the CKEditor 5 webpack plugin. Check out the UI language guide to learn more. When unspecified, 'en' is passed to the test runner.
• --additional-languages="ar,pl,..." – Specifies extra languages passed to the CKEditor 5 webpack plugin. Check out the UI language guide to learn more.
• --debug (alias -d) – Allows specifying custom debug flags. For example, the --debug engine option uncomments the // @if CK_DEBUG_ENGINE // lines in the code. Note that by default --debug is set to true even if you did not specify it. This enables the base set of debug logs (// @if CK_DEBUG //) which should always be enabled in the testing environment. You can completely turn off the debug mode by setting the --debug false option.
• --port – Specifies the port for the server to use. Defaults to 8125.
• --identity-file="/path/to/file.js" (alias -i) – Path to the file containing the license key(s) for closed–source features.

It starts the server available at http://localhost:8125.

# Creating a manual test

A manual test consists of 3 files:

• A <name>.md file with the test description.
• A <name>.js file with the JavaScript part of the test (e.g. the code initializing an editor).
• A <name>.html file with the HTML part of the test. It does not need to be an entire HTML page (with the doctype, etc.). It can include just the HTML elements that you want to define.

All 3 files are combined together and create a single manual test.

An example Markdown file:

## Create a new link

1. Select a fragment of the regular text.
2. Click the toolbar "Link" button.
3. Check if the balloon panel attached to the selection appeared.
4. Fill in the "Link URL" input in the panel.
5. Click the "Save" button.
6. Check if the selected text is converted into a link.

An example HTML file:

<head>
    <style>
        /*
          Some additional styles which this test needs.
          And yes – the test builder will merge this tag with the head defined in the template.
        */
    </style>
</head>

<div id="editor">...</div>

An example JavaScript file:

/* globals console, window, document */

import ClassicEditor from '@ckeditor/ckeditor5-editor-classic/src/classic.js';
import Essentials from '@ckeditor/ckeditor5-essentials/src/essentials.js';
import Paragraph from '@ckeditor/ckeditor5-paragraph/src/paragraph.js';

ClassicEditor
    .create( document.querySelector( '#editor' ), {
        plugins: [ Essentials, Paragraph ]
    } )
    .then( editor => {
        window.editor = editor;
    } )
    .catch( err => {
        console.error( err.stack );
    } );

# Verifying all manual tests

To verify that all manual tests can be opened without any errors (the crawler does not execute the manual test steps, it just visits the page), you do not need to do that manually, page by page. Instead, there is a web crawler that automatically traverses the documentation and it visits all pages that have been found. The crawler opens a headless Chromium browser and logs to the console any error that has been found.

To check manual tests, start the server (yarn manual --files=XYZ), and then run the crawler:

yarn run manual:verify

Read more about the crawler in Verifying documentation.

# Test suite and CI

To ensure the highest quality, we maintain a complete test suite with a stable 100% of code coverage for each of the packages. As of September 2019, this means over 11000 tests and the number is growing. Since every package is tested separately, we implement lower-level tests for libraries and higher-level tests for end-user features.

Such an extensive test suite requires a proper continuous integration service. We use Travis CI as a build platform. This service ensures seamless and fast developer experience and allows us to focus on the job.

Besides automated tests, we also maintain a smaller set of manual tests. They help us verify whether something unexpected happens that might have been missed by the automated tests.

When proposing a pull request make sure to add test(s) that verifies it. Every code change should be accompanied by a test which proves that it is needed. Such a strict approach to testing ensures that we have not only 100% of code coverage (which is quite easy to achieve and gives only illusory safety) but also a high level of coverage for cases that we failed to notice initially (and might do that again in the future).