Running Mocha + Istanbul + Babel
Using Babel 6.x, let's say we have file test/pad.spec.js
:
import pad from '../src/assets/js/helpers/pad';
import assert from 'assert';
describe('pad', () => {
it('should pad a string', () => {
assert.equal(pad('foo', 4), '0foo');
});
});
Install a bunch of crap:
$ npm install babel-istanbul babel-cli babel-preset-es2015 mocha
Create a .babelrc
:
{
"presets": ["es2015"]
}
Run the tests:
$ node_modules/.bin/babel-node node_modules/.bin/babel-istanbul cover \
node_modules/.bin/_mocha -- test/pad.spec.js
pad
✓ should pad a string
1 passing (8ms)
=============================================================================
Writing coverage object [/Volumes/alien/projects/forked/react-flux-puzzle/coverage/coverage.json]
Writing coverage reports at [/Volumes/alien/projects/forked/react-flux-puzzle/coverage]
=============================================================================
=============================== Coverage summary ===============================
Statements : 100% ( 4/4 )
Branches : 66.67% ( 4/6 ), 1 ignored
Functions : 100% ( 1/1 )
Lines : 100% ( 3/3 )
================================================================================
UPDATE: I've had success using nyc
(which consumes istanbul
) instead of istanbul
/babel-istanbul
. This is somewhat less complicated. To try it:
Install stuff (you can remove babel-istanbul
and babel-cli
):
$ npm install babel-core babel-preset-es2015 mocha nyc
Create .babelrc
as above.
Execute this:
$ node_modules/.bin/nyc --require babel-core/register node_modules/.bin/mocha \
test/pad.spec.js
...which should give you similar results. By default, it puts coverage info into .nyc-output/
, and prints a nice text summary in the console.
Note: You can remove node_modules/.bin/
from any of these commands when placing the command in package.json
's scripts
field.
PS: I now recommend to use single jest instead of mocha/instanbul/nyc/chai/etc.
Solution A: Using nyc and babel-plugin-istanbul
Setup (don't forget :@next
for nyc
)
npm install --save-dev nyc babel-plugin-istanbul babel-register
Add an env to babel
config:
{
"env": {
"nyc": { "plugins": ["istanbul"] }
}
}
nyc
config:
{
"reporter" : ["text", "text-summary", "lcov", "html"],
"include" : ["src/**/*.js"],
"require" : ["babel-register"],
"sourceMap" : false,
"instrument" : false,
"all" : true
}
PS: include
field needs to be specified in .nycrc
of in package.json
, if specified in command line, coverage will not works
Running the tests:
# 1. Build
NODE_ENV=nyc babel src --out-dir lib
# 2. Coverage
nyc mocha
Solution B: No extra packages : Only the basic ones
Work has been done recently on istanbul (1.0.0-alpha.2) to support Babel generated code with sourcemaps (see #212 and this for an example).
There are 2 ways:
- A. Tests written against previously transpiled code
- B. Tests written against original code and transpiled all together in memory at runtime
B1. Tests that exports (previously) transpiled code
This is done in 2 steps: Firstly, build your source with babel (e.g. from ./src to ./out) and write your tests against transpiled source (export foo from "./out/foo";
).
Then you will be able to run the tests using istanbul 1.0.0-alpha.2 :
istanbul cover _mocha -- ./test --compilers js:babel-register
Now if you want code coverage to follow the original code you've written (not the transpiled one), make sure to build with babel source-maps options set to both :
babel ./src --out-dir ./out --source-maps both
PS: If needed you can also do :
istanbul cover _mocha -- ./test --compilers js:babel-register \
--require babel-polyfill \
--require should \
--require sinon
B2. Tests that directly exports original code
In this case you write your tests against original source (export foo from "./src/foo";
), and with no further step, you directly run istanbul 1.0.0-alpha.2 using babel-node against cli.js :
babel-node ./node_modules/istanbul/lib/cli.js cover _mocha -- ./test
PS: If needed you can also do :
babel-node ./node_modules/istanbul/lib/cli.js cover _mocha -- ./test
--require babel-polyfill \
--require should \
--require sinon