New Rule: Don't reassign to dependency parameters

[cowchimp]

Hi.
Thanks for this great plugin!

I'm interested in sending a PR to add a new rule.
Wanted your take\input before I take the time to work on it.

The goal of this rule is to catch cases where one of the parameters in the module function is reassigned.
It's easy to miss that the variable you think refers to the dependency now refers to something else.

Please LMK if you think you'd be interested in something like this,
and if so, some pointers on what I should pay attention to to increase changes of accepting the PR.

Thanks!

Invalid code example (only the assignment of a is invalid):

define(['path/to/a', 'path/to/b'], function(a, b) {
  a = 1;
  var c = b;
  c = 2;
});

Rule implementation (wip)

function create(context) {
    const params = [];
    return {
        CallExpression(node) {
            if (!isAmdWithCallback(node)) return;
            const moduleFunction = getModuleFunction(node);
            params = moduleFunction.params.map(x => x.name);
        },
        AssignmentExpression(node) {
            if (node.left.type !== "Identifier") return;
            const name = node.left.name;
            if (params.some(x => x === name)) {
                context.report(node, `Cannot assign to a module dependency named ${name}`);
            }
        }
    };
}

[cvisco]

@cowchimp eslint has the no-param-reassign rule that covers this case. Would that work for what you're trying to do?

[cowchimp]

I didn't realize that eslint had that rule.
Thanks.

This would be a reduced case of that rule but only for the parameters of the AMD module function.
It would make sense to use if you already have too many violations in your code for no-param-reassign to fix, but you want to enforce no param reassigning for AMD dependencies at the very least.

[cvisco]

@cowchimp sorry for the delay. Yep, I could see a no-dependency-reassign rule as useful for those code bases that don't want to implement the rule everywhere. If you'd like to submit a PR for this, I'll add it in.