# node-tap

A <abbr title="Test Anything Protocol">TAP</abbr> test framework for
Node.js.

[![Build Status](https://travis-ci.org/tapjs/node-tap.svg?branch=master)](https://travis-ci.org/tapjs/node-tap)

_Just wanna see some code? [Get started!](http://www.node-tap.org/basics/)_

It includes a command line test runner for consuming TAP-generating
test scripts, and a JavaScript framework for writing such scripts.

* [Getting started guide](http://www.node-tap.org/basics/)
* Built-in [test coverage](http://www.node-tap.org/coverage/)
* Many [reporter formats](http://www.node-tap.org/reporting/)
* Extensive [API](http://www.node-tap.org/api/) featuring:
  * Great [promise support](http://www.node-tap.org/promises/)
  * Comprehensive [assert library](http://www.node-tap.org/asserts/)
  * Other [advanced stuff](http://www.node-tap.org/advanced/)
  * Mocha-like [BDD DSL](http://www.node-tap.org/mochalike/)
  * [Parallel Testing](http://www.node-tap.org/parallel/)
* [Command-line interface](http://www.node-tap.org/cli/) for running
  tests (whether they use node-tap or not)

See [the changelog](http://www.node-tap.org/changelog/) for recent updates, or just get
started with [the basics](http://www.node-tap.org/basics/).

All this is too much to manage in a single README file, so head over
to [the website](http://www.node-tap.org/) to learn more.

## Why TAP?

Why should you use this thing!?  **LET ME TELL YOU!**

Just kidding.

Most frameworks spend a lot of their documentation telling you why
they're the greatest.  I'm not going to do that.

### <i lang="it">tutti i gusti sono gusti</i>

Software testing is a software and user experience design challenge
that balances on the intersection of many conflicting demands.

Node-tap is based on [my](http://izs.me) opinions about how a test
framework should work, and what it should let you do.  I do _not_ have
any opinion about whether or not you share those opinions.  If you do
share them, you will probably enjoy this test library.

1. **Test files should be "normal" programs that can be run
   directly.**

   That means that it can't require a special runner that
   puts magic functions into a global space.  `node test.js` is a
   perfectly ok way to run a test, and it ought to function
   exactly the same as when it's run by the fancy runner with
   reporting and such.  JavaScript tests should be JavaScript
   programs; not english-language poems with weird punctuation.

2. **Test output should be connected to the structure of the
   test file that is easy to determine.**

   That means not unnecessarily deferring test functions
   until `nextTick`, because that would shift the order of
   `console.log` output.  Synchronous tests should be synchronous.

3. **Test files should be run in separate processes.**

   That means that it can't use `require()` to load test files.  Doing
   `node ./test.js` must be the exact same sort of environment for the
   test as doing `test-runner ./test.js`.  Doing `node test/1.js; node
   test/2.js` should be equivalent (from the test's point of view) to
   doing `test-runner test/*.js`.  This prevents tests from becoming
   implicitly dependent on one anothers' globals.

4. **Assertions should not normally throw (but throws MUST be handled
   nicely).**

   I frequently write programs that have many hundreds of
   assertions based on some list of test cases.  If the first failure
   throws, then I don't know if I've failed 100 tests or 1, without
   wrapping everything in a try-catch.  Furthermore, I usually want to
   see some kind of output or reporting to verify that each one
   actually ran.

   Basically, it should be your decision whether you want to throw or
   not.  The test framework shouldn't force that on you, and should
   make either case easy.

5. **Test reporting should be separate from the test process, included
   in the framework, and enabled by default for humans.**

   The [raw test output](http://www.node-tap.org/tap-format/) should
   be machine-parseable and human-intelligible, and a separate process
   should consume test output and turn it into a [pretty summarized
   report](http://www.node-tap.org/reporting/).  This means that test
   data can be stored and parsed later, dug into for additional
   details, and so on.  Also: nyan cat.

6. **Writing tests should be easy, maybe even fun.**

   The lower the barrier to entry for writing new tests, the more
   tests get written.  That means that there should be a relatively
   small vocabulary of actions that I need to remember as a test
   author.  There is no benefit to having a distinction between a
   "suite" and a "subtest".  Fancy DSLs are pretty, but more to
   remember.

   That being said, if the you returns a Promise, or use a DSL that
   throws a decorated error, then the test framework should Just Work
   in a way that helps a human being understand the situation.

7. **Tests should output enough data to diagnose a failure, and no
   more or less.**

   Stack traces pointing at JS internals or the guts of the test
   framework itself are not helpful.  A test framework is a serious UX
   challenge, and should be treated with care.

8. **Test coverage should be included.**

   Running tests with coverage changes the way that you think about
   your programs, and provides much deeper insight.  Node-tap bundles
   [nyc](https://istanbul.js.org/) for this.

   It's not enabled by default only because it _does_ necessarily
   change the nature of the environment a little bit.  But I strongly
   encourage [enabling coverage](http://www.node-tap.org/coverage/).

9. **Tests should be output in a predictable order.**

   Even if they are run in parallel, the test _output_ should be
   consistent.

   As of version 10, tap supports [parallel
   tests](http://www.node-tap.org/parallel/), which
   can make your tests run significantly faster if they are I/O bound
   or if you have multiple cores on your machine.  However, even when
   run in parallel, the output is still serialized.

10. **Tests should not require more building than your code.**

    Babel and Webpack are lovely and fine.  But if your code doesn't
    require compilation, then I think your tests shouldn't either.
    Tap is extremely
    [promise-aware](http://www.node-tap.org/promises/), but works on
    any version of Node.js back to v0.10.

Software testing should help you build software.  It should be a
security blanket and a quality ratchet, giving you the support to
undertake massive refactoring and fix bugs without worrying.  It
shouldn't be a purification rite or a hazing ritual.

There are many opinions left off of this list!  Reasonable people can
disagree.  But if you find yourself nodding along, [maybe tap is for
you](http://www.node-tap.org/basics/).
