no-object-mutation does not respect the prefix setting

[karol-majewski]

Hello and thank you for your work.

Context

In React, it's common to assign defaultProps via direct property assignment.

export const Foo: React.FunctionComponent = /* ... */

Foo.defaultProps = {
  name: "Bob",
};

Adding defaults this way make sense for two reasons:

• Functional composition doesn't work well with generic components in TypeScript
• TypeScript 3.0 introduced LibraryManagedAttributes that should automagically improve type inference if you assign defaultProps the traditional way

The problem

I used to use this setting:

"no-object-mutation": [true, { "ignore-prefix": ["defaultProps"] }]

And it worked fine — assignment to any property called defaultProps was allowed. However, in tslint-immutable@5.5.2 such an assignment triggers an error.

It's impractical to whitelist every possible component name in your application:

"no-object-mutation": [true, { "ignore-prefix": ["Foo.defaultProps", "Bar.defaultProps"] }]

So respecting the setting (just like it used to be) seems like the way to go.

[RebeccaStevens]

Thanks for the issue.
I should be able to be able to look into this issue within the next few days (but no promises).

[RebeccaStevens]

@karol-majewski

I've just had a quick look at this but I haven't been able to reproduce the old behaviour you mention. What version of tslint-immutable were you able use "no-object-mutation": [true, { "ignore-prefix": ["defaultProps"] }] on to get your desired effect?

I don't thing the "ignore-prefix" option was ever setup to allow this.

For now I'm going to remove the bug label and add the enhancement label (as there should be a way to get your desired effect).

[karol-majewski]

@RebeccaStevens Thank you for taking the time to get back to me.

The bad news is, I don't have access to the original package anymore (tslint-immutable was part of a config used in the company I used to work for). The only thing I know is that assigning to defaultProps was allowed — but if you say it's been always like that, then perhaps we just had turned the rule off. If that's the case, then I apologize for misleading you into thinking it once worked differently.

I would still love to see it as an option though!

[RebeccaStevens]

Closed via #137