Does not work with other plugins when chai loaded multiple times

[jreichenberg]

Hi,

I've created my own chai plugin with custom assertions. In order to get it working with chai-as-promised I found I needed to load my custom plugin first in my test spec (Mocha via NodeJs) and then chai-as-promised:

var chai = require('chai'),
    myCustomAssertions = require('...');

chai.use(myCustomAssertions);
chai.use(require('chai-as-promised'));

The above works fine if its the only spec running. If I switch the order of the use statements then chai-as-promised does not hook my custom assertions and they get fed unresolved promises.

The problem is that if I load multiple spec files, and the ones loaded first use chai-as-promised but not my custom assertions, then chai.use() does nothing as the chai-as-promised library has already done its stuff and my custom assertions are no longer hooked and modified by chai-as-promised.

Spec 1 in Node/Mocha process:

var chai = require('chai');
chai.use(require('chai-as-promised'));

Spec 2 in same Node/Mocha process:

var chai = require('chai'),
    myCustomAssertions = require('...');

chai.use(myCustomAssertions);
chai.use(require('chai-as-promised'));

Suggestions? Make sense?

[domenic]

This is working as intended. Generally you should only add a plugin once in a given Node program.

[jreichenberg]

Thanks for the reply, and makes sense and agree in general...and chai itself maintains a list of already added plugins to make subsequent use() calls on the same plugin a no-op. So I get your point and we can close out this issue.

However, chai-as-promised seems a little different from other plugins in that it modifies the behavior of existing assertions.

I wonder if anyone using this project can suggest a best-practice for a test spec that has chai-as-promised + another plugin and can be run on its own and with other test specs...all the options I can think of are inelegant. It makes sense to me for each test spec to require the plugins it uses rather than some wrapping thing have fore-knowledge of what chai plugins would be needed in the aggregate.

[Atlas7]

chai.use plugin newbie here. Say if I want to use the following two plugins together, is that possible / discouraged?

chai.use(chaiAsPromised)
chai.use(chaiImmutable)

I haven't really tried it yet but on top of my mind what if in a Mocha test, we have async functions (that requires chaiAsPromised), and immutable data structures (that requires chaiImmutable)?

Apologies if this question sounds very dumb - in advance!