tmatch

tmatch

This module exists to facilitate the t.match() method in tap.

It checks whether a value matches a given "pattern". A pattern is an object with a set of fields that must be in the test object, or a regular expression that a test string must match, or any combination thereof.

The algorithm is borrowed heavily from only-shallow, with some notable differences with respect to the handling of missing properties and the way that regular expressions are compared to strings.

usage

var matches = require('tmatch')

if (!matches(testObject, pattern)) console.log("yay! diversity!");

// somewhat more realistic example..
http.get(someUrl).on('response', function (res) {
  var expect = {
    statusCode: 200,
    headers: {
      server: /express/
    }
  }

  if (!tmatch(res, expect)) {
    throw new Error('Expect 200 status code from express server')
  }
})

details

Copied from the source, here are the details of only-shallow's algorithm:

1. If the object is a string, and the pattern is a RegExp, then return true if pattern.test(object).
2. Use loose equality (==) only for all other value types (non-objects). tmatch cares more about shape and contents than type. This step will also catch functions, with the useful (default) property that only references to the same function are considered equal. 'Ware the halting problem!
3. null is an object – a singleton value object, in fact – so if either is null, return object == pattern.
4. Since the only way to make it this far is for object or pattern to be an object, if object or pattern is not an object, they're clearly not a match.
5. It's much faster to compare dates by numeric value (.getTime()) than by lexical value.
6. Compare RegExps by their components, not the objects themselves.
7. The parts of an arguments list most people care about are the arguments themselves, not the callee, which you shouldn't be looking at anyway.
8. Objects are more complex:
   1. Return true if object and pattern both have no properties.
   2. Ensure that cyclical references don't blow up the stack.
   3. Ensure that all the key names in pattern exist in object.
   4. Ensure that all of the associated values match, recursively.

license

ISC. Go nuts.