[naming-convention] camelCase format doesn't work if prefix is configured

[villelahdenvuo]

Repro

{
  "rules": {
	"@typescript-eslint/naming-convention": [
		"error",
		{
			"selector": "variable",
			"types": ["boolean"],
			"format": ["camelCase"],
			"prefix": ["is", "should", "has", "can", "did", "will"]
		}
	]
  }
}

const isStore = isPlainObject(store) && isPlainObject(store.storefront) && isPlainObject(store.locale);

Expected Result

No error.

Actual Result

Variable name isStore must match one of the following formats: camelCase eslint@typescript-eslint/naming-convention

Additional Info

If I remove the prefix option the format rule works.

Versions

package	version
@typescript-eslint/eslint-plugin	3.1.0
@typescript-eslint/parser	3.1.0
TypeScript	3.8.3
ESLint	7.2.0
node	13.13.0
npm	6.14.5

[bradzacher]

This is intentional. See: https://github.com/typescript-eslint/typescript-eslint/blob/master/packages/eslint-plugin/docs/rules/naming-convention.md#format-options

If you define a prefix, it is removed from the name before checking the format. This is done because otherwise you cannot do something like StrictPascalCase with a prefix (i.e. TMyType would never be able to match StrictPascalCase, due to the two capitals).

This is also shown in the example for configuring boolean names are prefixed with a verb:
https://github.com/typescript-eslint/typescript-eslint/blob/master/packages/eslint-plugin/docs/rules/naming-convention.md#enforce-that-boolean-variables-are-prefixed-with-an-allowed-verb

[villelahdenvuo]

@bradzacher Thanks, that definitely makes sense. To avoid this issue in the future I made a PR to note this more visibly in the docs. ✨