Function type aliases not considered in `valid-title` and `prefer-describe-function-title`

[FloEdelmann]

Consider this code:

// validator.ts
export type Validator = () => boolean

export const validator1: Validator = () => true
export const validator2: Validator = () => true

// validator.spec.ts
import { validator1 } from './validator.ts'

describe('validator1', () => { … })
describe(validator2, () => { … })

With typecheck: true, no prefer-describe-function-title error is reported for 'validator1', although I would have expected it to suggest using validator1 as the title instead. With typecheck: false (default), prefer-describe-function-title reports an error as expected.

In either case, valid-title reports an error for validator2, telling me that validator2 is not a valid title, although it is a function and thus should be supported.

CC @JoshuaKGoldberg as the rule author (#690)

[JoshuaKGoldberg]

Amusing. I was hoping it would be more than a day after #690 that a bug report would be filed. 😄

For context, #690 had prefer-describe-function-title reuse the existing logic from valid-title:

eslint-plugin-vitest/src/utils/types.ts

Lines 78 to 91 in 7d9d12c

	export function isClassOrFunctionType(type: ts.Type): boolean {
	return type
	.getSymbol()
	?.getDeclarations()
	?.some(
	declaration =>
	ts.isArrowFunction(declaration)
	|| ts.isClassDeclaration(declaration)
	|| ts.isClassExpression(declaration)
	|| ts.isFunctionDeclaration(declaration)
	|| ts.isFunctionExpression(declaration)
	|| ts.isMethodDeclaration(declaration)
	) ?? false
	}

This bug is fixed for me locally and all existing tests pass if we switch to checking the type itself for call or construct signatures, rather than getting its symbol declaration:

export function isClassOrFunctionType(type: ts.Type): boolean {
  return (
    type.getCallSignatures().length > 0
    || type.getConstructSignatures().length > 0
  )
}