rewire
Dependency injection for node.js applications.
rewire adds a special setter and getter to modules so you can modify their behaviour for better unit testing. You may
- introduce mocks for other modules
- leak private variables
- override variables within the module.
rewire does not load the file and eval the contents to emulate node's require mechanism. In fact it uses node's own require to load the module. Thus your module behaves exactly the same in your test environment as under regular circumstances (except your modifications).
Debugging is fully supported.
Installation
npm install rewire
For older node versions:
rewire is tested with node 0.7.x. I recommend to run the unit tests via mocha
in the rewire-folder before using rewire with older node versions.
Examples
var rewire = require("rewire");
var myRewiredModule = rewire("../lib/myModule.js");
myRewiredModule === require("../lib/myModule.js");
myModule.__set__("myPrivateVar", 123);
myModule.__get__("myPrivateVar");
myModule.__set__("fs", {
readFile: function (path, encoding, cb) {
cb(null, "Success!");
}
});
myModule.readSomethingFromFileSystem(function (err, data) {
console.log(data);
});
myModule === require("./myModule.js");
myModule.__set__({
fs: fsMock,
http: httpMock,
someOtherVar: "hello"
});
myModule.__set__({
console: {
log: function () { }
},
process: {
argv: ["testArg1", "testArg2"]
}
});
myModule.__set__("console.log", function () { });
assert.ok(myModule.__get__("currentState") === "idle");
rewire("./myModule.js", false) === require("./myModule.js");
rewire("./myModule.js") === rewire("./myModule.js");
rewire.reset();
##API
rewire(filename, cache): {RewiredModule}
-
{!String} filename:
Path to the module that shall be rewired. Use it exactly like require().
-
{Boolean=true} cache (optional):
Indicates whether the rewired module should be cached by node so subsequent calls of require()
will
return the rewired module. Further calls of rewire()
will always overwrite the cache.
rewire.reset()
Removes all rewired modules from require.cache
. Every require()
will now return the original module again.
RewiredModule.__set__(name, value)
RewiredModule.__set__(env)
- {!Object} env:
Takes all keys as variable names and sets the values respectively.
RewiredModule.__get__(name): {∗}
Returns the private variable.
Credits
This module is inspired by the great injectr-module.
License
(The MIT License)
Copyright (c) 2012 Johannes Ewald <mail@johannesewald.de>
Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
'Software'), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:
The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.