rspec/rules/S3415/javascript/rule.adoc

== Why is this an issue?

Many assertion functions have specific parameters for the expected and actual values. Swap them, and your test will still have the same outcome (succeed/fail when it should) but the error messages will be confusing.


This rule raises an issue when the "expected" argument of an assertion function is a hard-coded value and the "actual" argument is not.


This rule currently supports Chai assertions.

=== Noncompliant code example

[source,javascript]
----
const assert = require('chai').assert;
const expect = require('chai').expect;
const should = require('chai').should();

it("inverts arguments", function() {
    assert.equal(42, aNumber); // Noncompliant
    expect(42).to.equal(aNumber); // Noncompliant
    should.fail(42, aNumber);  // Noncompliant
});
----

=== Compliant solution

[source,javascript]
----
const assert = require('chai').assert;
const expect = require('chai').expect;
const should = require('chai').should();

it("inverts arguments", function() {
    assert.equal(aNumber, 42);
    expect(aNumber).to.equal(42);
    should.fail(aNumber, 42); 
});
----

ifdef::env-github,rspecator-view[]

'''
== Implementation Specification
(visible only on this page)

=== Message

If a Chai function gets actual and expected values as arguments:

* Swap these 2 arguments so they are in the correct order: actual value, expected value.
If expect(actual).someMethod(expected) is used:

* Swap this argument with the one given to "expect".


=== Highlighting

If a Chai function gets actual and expected values as arguments:

* Primary: second argument to swap
* Secondary: first argument to swap
** message: 'Other argument to swap.'

If expect(actual).someMethod(expected) is used:

* Primary: The argument of the assertion function (ex: "equal")
* Secondary: The argument given to "expect"
** no message


'''
== Comments And Links
(visible only on this page)

include::../comments-and-links.adoc[]
endif::env-github,rspecator-view[]