match toBe(null) and possibly toEqual(null) in addition to toBeNull

[julienw]

In a few rules (eg: prefer-document) toBeNull() will be replaced by toBeInTheDocument() which is nice.

Is it possible to match toBe(null) and toEqual(null) as well?

Thanks!

[benmonro]

Should be. Care to open a PR?

[julienw]

TBH I would love to, but I don't know how to write eslint rules. If you know similar examples I could have a look, but for now I looked at the source code for this rule and I have no idea how to change that...

[benmonro]

for sure, it's a great skill to learn and once you do it's actually a ton of fun! The docs on eslint are a good placed to start. A thing to note, the function names are AST selectors (think CSS selectors, but for code). that may seem strange, but consider this code:

const foo = { "bar": function() {} };

then consider that this function can use the shorthand notation like this:

const foo = { "bar"() {} };

and if you have a variable you can do this:

const x = "baz";

const foo = { [`bar ${x}`]() {} }

which could be called like this:

foo["bar baz"]();

an eslint rule uses that pattern (as many of the rules in this plugin do) to declaratively handle various use cases. So for example, if you wanted a rule to match all CallExpressions you would do

{ "CallExpression"(node) { ... } }

if you wanted a rule to match all call expressions that were named 'foo' (as in foo()), you would do this:

{"CallExpression[callee.name=foo]"(node) { ... }}

(that might look familiar if you've ever written a CSS selector like div[role=button], that's because it is. :)
You might be wondering how you can know what all the various types and properties etc, don't worry astexplorer.net has you covered there. It's a great tool and this entire plugin was written using it. It's like a dom-inspector for code, and you can play around with rules in real time (among other things).

[julienw]

Thanks for the pointers, I think I managed to do something.

[github-actions]

🎉 This issue has been resolved in version 3.7.0 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

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