markdown-doctest

Test all the code in your markdown docs!

Why on earth?

As an open source developer, there are few things more embarrassing than a user opening an issue to inform you that your README example is broken! With markdown-doctest, you can rest easy knowing that your example code is actually runnable.

Installation

Just npm install markdown-doctest and run markdown-doctest. It will run all of the Javascript code examples tucked away in your markdown, and let you know if any blow up.

Okay, how do I use it?

Let's try it on this repo!

var a = 5;

var b = 10;

console.log(a + c);

There's a problem with that example. markdown-doctest finds it for us:

$ markdown-doctest
x..

Failed - README.md:32:17
evalmachine.<anonymous>:7
console.log(a + c);
                ^

ReferenceError: c is not defined

Awesome! No excuse for broken documentation ever again, right? 😉

We can also run specific files or folders by running markdown-doctest with a glob, like markdown-doctest docs/**/*.md. By default markdown-doctest will recursively run all the .md or .markdown files starting with the current directory, with the exception of the node_modules directory.

Note: markdown-doctest doesn't actually attempt to provide any guarantee that your code worked, only that it didn't explode in a horrible fashion. If you would like to use markdown-doctest for actually testing the correctness of your code, you can add some asserts to your examples.

markdown-doctest is not a replacement for your test suite. It's designed to run with your CI build and give you peace of mind that all of your examples are at least vaguely runnable.

So how do I write those examples?

In your markdown files, anything inside of code blocks with 'js' or 'es6' will be run. E.g:

```js
console.log("Yay, tests in my docs");
```

```es6
const a = 5;
console.log({a, foo: 'test'});
```

I have a code example I don't want tested!

You can tell markdown-doctest to skip examples by adding <!-- skip-example --> before the example. E.g:

<!-- skip-example -->
```js
// not a runnable example

var foo = download(...);
```

How do requires work? And other setup logic?

You can require any needed modules or example helpers in .markdown-doctest-setup.js. E.g:

// .markdown-doctest-setup.js
module.exports = {
  require: {
    Rx: require('rx')
  },

  globals: {
    $: require('jquery')
  }
}

Anything exported under require will then be used by any examples that require that key. You must explicitly configure all of the dependencies used in your examples.

Anything exported under globals will be available globally across all examples.

You can also specify a regexRequire section to handle anything more complex than an exact string match!

// .markdown-doctest-setup.js
module.exports = {
  require: {
    Rx: require('rx')
  },

  regexRequire: {
    'rx/(.*)': function (fullPath, matchedModuleName) {
      return require('./dist/' + matchedModuleName);
    }
  }
}

Do I have to enable es6 support?

Nope, ES6 support is on by default. You can disable babel support in your .markdown-doctest-setup.js file. This will speed things up drastically:

//.markdown-doctest-setup.js
module.exports = {
  babel: false
}

What if I have global state that needs to be reset after my examples run?

//.markdown-doctest-setup.js
module.exports = {
  beforeEach: function () {
    // reset your awesome global state
  }
}

You can specify a function to be run before each example in your .markdown-doctest-setup.js.

What if I want to remove custom syntax from examples before processing?

//.markdown-doctest-setup.js
module.exports = {
  transformCode(code) {
    // Remove ... from code syntax
    return code.replace(/\.\.\./g, "");
  }
}

Who uses markdown-doctest?

All of these projects either run markdown-doctest with npm test or as part of their CI process:

• lodash
• Moment
• RxJS
• most
• xstream
• cyclejs/time
• rx.schedulers
• rx.priorityqueue
• rx.disposables
• rx-undoable