In node I use simple test libraries like tap or tape that let you run the test files directly. For code that needs to run in both the browser and node I use tape because tap doesn't run in the browser very well and the APIs are mostly interchangeable.

The simplest kind of test I might write in test/ looks like:

var test = require('tape');
var someModule = require('../');

test('fibwibblers and xyrscawlers', function (t) {
    t.plan(2);
    
    var x = someModule();
    t.equal(x.foo(2), 22);
    
    x.beep(function (err, res) {
        t.equal(res, 'boop');
    });
})

To run a single test file in node I just do:

node test/fibwibbler.js

And if I have multiple tests I want to run I do:

tape test/*.js

or I can just use the tap command even if I'm just using tape because tap only looks at stdout for tap output:

tap test/*.js

The best part is that since tape just uses console.log() to print its tap-formatted assertions, all I need to do is browserify my test files.

To compile a single test in the browser I can just do:

browserify test/fibwibbler.js > bundle.js

or to compile a directory full of tests I just do:

browserify test/*.js > bundle.js

Now to run the tests in a browser I can just write an index.html:

<script src="bundle.js"></script>

and xdg-open that index.html in a local browser. To shortcut that process, I can use the testling command (npm install -g testling):

browserify test/*.js | testling

which launches a browser locally and prints the console.log() statements that executed browser-side to my terminal directly. It even sets the process exit code based on whether the TAP output had any errors:

substack : defined $ browserify test/*.js | testling

TAP version 13
# defined-or
ok 1 empty arguments
ok 2 1 undefined
ok 3 2 undefined
ok 4 4 undefineds
ok 5 false[0]
ok 6 false[1]
ok 7 zero[0]
ok 8 zero[1]
ok 9 first arg
ok 10 second arg
ok 11 third arg
not ok 12 (unnamed assert)
  ---
    operator: ok
    expected: true
    actual:   false
    at: Test.ok.Test.true.Test.assert (http://localhost:47079/__testling?show=true:7772:10)
  ...
# (anonymous)
ok 13 should be equal

1..13
# tests 13
# pass  12
# fail  1
substack : defined $ echo $?
1
substack : defined $

coverage

bonus content: if I want code coverage, I can just sneak that into the pipeline using coverify. This is still experimental but here's how it looks:

$ browserify -t coverify test.js | testling | coverify

TAP version 13
# beep boop
ok 1 should be equal

1..1
# tests 1
# pass  1

# ok

# /tmp/example/test.js: line 7, column 16-28

  if (err) deadCode();
           ^^^^^^^^^^^

# /tmp/example/foo.js: line 3, column 35-48

  if (i++ === 10 || (false && neverFires())) {
                              ^^^^^^^^^^^^

or to run the tests in node, just swap testling for node:

$ browserify -t coverify test.js | node | coverify
TAP version 13
# beep boop
ok 1 should be equal

1..1
# tests 1
# pass  1

# ok

# /tmp/example/test.js: line 7, column 16-28

  if (err) deadCode();
           ^^^^^^^^^^^

# /tmp/example/foo.js: line 3, column 35-48

  if (i++ === 10 || (false && neverFires())) {
                              ^^^^^^^^^^^^

Happy-Ferret/how_i_write_tests_for_node_and_the_browser.markdown

coverage