# 3. Use Jest for automated tests
Date: 2020-06-01
# Status
Accepted
# Context
Automated testing is by now a standard in every quality software develpment process. The benefits are many, productivity increase, time saving, better quality. Specifically for this plugin, there are many checkpoints that have to be verified on each code change, including but not limited to:
- Does the code work as its supposed to do after the change? Maybe the generated paths are not correct any more or even empty? Did we miss a trailing slash somewhere?
- Does the plugin even work with the given input of the Vuepress framework? Maybe when given a Page with no title, it breaks?
- Does the plugin even work when included in Vuepress? Does Vuepress build process finish successfully when the plugin is included?
The above require a manual testing process, for each code change.
From the many javascript testing frameworks, Jest is one
of the most popular ones (for example its the default test framework to use with React)
that can automate the above tasks. It supports writing very simple tests, in
javascript but also typescript through ts-jest.
# Decision
We will use Jest as the testing framework.
# Consequences
- The developed codebase will be accompanied by automated tests
- Before every commit or PR, the tests need to pass successfully
- The code must be tested to the fullest extend: strive for 100% coverage as much as possible.
Install jest, ts-jest and its types with
npm install --save-dev jest ts-jest @types/jest
Use the key jest in package.json to configure the
framework. Note that when typescript is used to write the tests, for the IDE
autocomplete features to work, the test files path needs to be included in
the include paths of typescript in tsconfig.json. However this will have
the test folder and all its files be included in the production-ready
compiled files which is not what is usually needed. To acccount for this,
create an additional tsconfig.json file in the tests/
folder which extends the main tsconfig.json file but ignores the output of
that folder. See this link
for more details.
Two types of test suites are identified as of now:
A unit test suite will verify that the classes of the plugin work as expected when given specific input, and provide the expected output. To run them use
npm run test:unitAn integration suite will verify that Vuepress build process completes successfully when the plugin is used. To
npm run test:integration
To run all tests instead use
npm run test
And to run all tests (or each test suite) in watch for changes mode use the
--watch flag as for example
npm run test:unit -- --watch