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code coverage command


Just run covert on some ordinary files:

$ covert test/*.js
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
# (anonymous)
ok 12 should be equal
# tests 12
# pass  12
# ok
# /home/substack/projects/defined/index.js: line 3, column 18-26
  if (false) dead();
# /home/substack/projects/defined/index.js: line 6, column 16-18, 19-25, 26-30, 31-51
  for (var i = 0; i < 5; i++) console.log('blah');
               ^  ^^^^^  ^^^  ^^^^^^^^^^^^^^^^^^^
# /home/substack/projects/defined/index.js: line 10, column 3-24
# coverage: 76/82 (92.68 %)
non-zero exit code in `coverify` command

In this example, this test suite is using tape. Tests written with tape can just be run directly using node, which fits very well with what this command expects.


With npm do:

npm install -g covert


usage: covert {OPTIONS} FILES
  Instrument FILES and in-module dependencies, writing coverage data to STDERR.
  OPTIONS are:
      Suppress normal output and print json coverage data to stdout.
    -q, --quiet  
      Only print coverage data, suppressing all other output.
    -c, --color
      Use color in the output. Default: true if stdout is a TTY.


Most code coverage libraries do weird things I don't like, such as writing all their junk to directories and files in a completely out-of-band way.


  • only uses stderr and stdout, doesn't write to any files. All of this business about lcov files and directories with reports in them really weirds me out.

  • bundles with browserify --bare and a transform instead of hijacking require(). All the reporting goes through a unix pipeline on process.stdin and process.stdout. This is still hacky, but it's the kind of hacky that you can fix yourself when the magic breaks down. The internal pipeline is just:

browserify -t coverify --bare $* | node | coverify
  • works really well with simple unix pipelines. stdin and stdout: the wisdom of the ancients.