babel-plugin-gwt
Data Driven Testing babel plugin inspired by Groovy's Spock framework
🖖
- ❤️ Data Tables
- 🛀 Clean tests
- 🎉 Multiple tests written once
- 💪 Optional given, when, then API
Problem
Writing clean descriptive tests can sometimes be difficult and cumbersome.
Solution
This plugin provides syntactic sugar to make writing well documented data driven tests easy and enjoyable.
Data Driven Testing is when we test the same behavior
multiple times with different parameters and assertions, babel-plugin-gwt's
data driven testing support makes this a
first class feature.
babel-plugin-gwt
gives your standard Javascript tests four new blocks given
, when
, then
, where
(you can
continue to use whichever test runner and assertion library that you like with this plugin).
-
given
, when
, then
blocks are used to generate your test title making it easier to write, read and maintain
your test.
-
Data Tables are supported with the where
block used to write test data for your test to be ran multiple times with
different inputs.
Installation
With npm:
npm install --save-dev babel-plugin-gwt
With yarn:
yarn add -D babel-plugin-gwt
Setup
.babelrc
{
"plugins": ["babel-plugin-gwt"]
}
CLI
babel --plugins babel-plugin-gwt script.js
Node
require('babel-core').transform('code', {
plugins: ['babel-plugin-gwt'],
})
Usage
Basic
A simple test with babel-plugin-gwt
could look something like:
it('add', () => {
given: 'a and b'
const a = 1;
const b = 1;
when: 'added'
const actual = a + b;
then: 'returns 2'
expect(actual).toBe(2);
});
↓ ↓ ↓ ↓ ↓ ↓
With Data Table
This test can become more powerful by using the where
block to run the same test multiple times with different data.
The where block allows you to define variables that are available anywhere in the test and to use the $
symbol in your
test title and given
, when
, then
blocks to interpolate values into the generated test title.
it('add', () => {
when: '$a is added to $b'
const actual = a + b;
then: '$expected is returned'
expect(actual).toBe(expected);
where: {
a | b || expected
0 | 0 || 0
1 | 0 || 1
0 | 1 || 1
1 | 1 || 2
}
});
↓ ↓ ↓ ↓ ↓ ↓
API
All label blocks are optional, and some like given
may not make sense for every test.
given
The given
block is used to describe the inputs of your test.
Example: given: 'some input'
when
The when
block is used to describe the behaviour being tested.
Example: when: 'something happens'
then
The then
block is used to describe the assertions being made.
Example: then: 'it should be ...'
where
The where
block is used to supply your test with a data table. The table must have the following structure:
- The first row must be variable names you wish to use within the test. These will be hoisted into the whole
scope of the test block and so can be used anywhere inside of the test.
- All other rows can be data and variables available in the outer scope that you may be testing
- Columns of data are separated with
|
, a convention is to use two pipes (||
) for any expected values (although
this is just a convention under the hood both |
and ||
are treated the same).
Example:
where: {
a | b || expected
0 | 0 || 0
1 | 0 || 1
0 | 1 || 1
1 | 1 || 2
}
interpolation
All description blocks (given
, when
, and then
) and the usual test description can add values to be interpolated
with the $
symbol infront of the variable name defined in the where
block table.
Supported testing frameworks
babel-plugin-gwt
supports all of the following test blocks: it
, fit
, xit
, it.only
, it.skip
, test
,
ftest
, xtest
, test.only
, test.skip
.
That means that the following frameworks are supported:
⚠️ Linting
Some of the syntaxes used within this plugin will more than likely upset most linters so it is probably advisable to
disable them within the tests using babel-plugin-gwt
.
For example eslint:
it('add', () => {
when: '$a is added to $b'
const actual = a + b;
then: '$expected is returned'
expect(actual).toBe(expected);
where: {
a | b || expected
0 | 0 || 0
1 | 0 || 1
0 | 1 || 1
1 | 1 || 2
}
});
❌ Object/Array literal broken syntax
Within the where block the first column does not support Object
({}
) or Array
([]
) literals
Not supported:
where: {
obj | key | value || expected
{} | 'foo' | 'bar' || { foo: 'bar' }
}
Supported:
where: {
key | obj | value || expected
'foo'| {} | 'bar' || { foo: 'bar' }
}
Other solutions
Contributors
LICENSE
MIT