fix(extractor): keep a protected constructor protected

packages/dtsx/test/protected-constructor.test.tsadded+69-0

Changes to packages/dtsx/test/protected-constructor.test.ts

		@@ -0,0 +1,69 @@
	1	+/**
	2	+ * A protected constructor was emitted as a public one:
	3	+ *
	4	+ * export class Singleton {
	5	+ * protected constructor(name: string) {}
	6	+ * static create(): Singleton { ... }
	7	+ * }
	8	+ *
	9	+ * emitted `constructor(name: string);`, so `new Singleton('x')` type-checked
	10	+ * against the declarations although only subclasses and the class itself may
	11	+ * construct it.
	12	+ */
	13	+import { describe, expect, it } from 'bun:test'
	14	+import { mkdtemp, rm, writeFile } from 'node:fs/promises'
	15	+import { tmpdir } from 'node:os'
	16	+import { join } from 'node:path'
	17	+import { runTsc } from './helpers/tsc'
	18	+import { processCode } from './test-utils'
	19	+
	20	+/** Type-check `consumer` against the generated declarations as `./index`. */
	21	+async function checkConsumer(dts: string, consumer: string): Promise<string> {
	22	+ const dir = await mkdtemp(join(tmpdir(), 'dtsx-protected-constructor-'))
	23	+ try {
	24	+ await writeFile(join(dir, 'index.d.ts'), dts)
	25	+ await writeFile(join(dir, 'use.ts'), consumer)
	26	+ return runTsc(dir, ['index.d.ts', 'use.ts']).output
	27	+ }
	28	+ finally {
	29	+ await rm(dir, { recursive: true, force: true })
	30	+ }
	31	+}
	32	+
	33	+describe('protected constructor', () => {
	34	+ it.each([
	35	+ [
	36	+ 'plain',
	37	+ 'export class Singleton {\n protected constructor(name: string) {}\n static create(): Singleton { return new Singleton(\'x\') }\n}\n',
	38	+ 'protected constructor(name: string);',
	39	+ 'import { Singleton } from \'./index\'\nconst s: Singleton = Singleton.create()\nexport class Named extends Singleton {\n constructor() { super(\'named\') }\n}\nnew Named()\n// @ts-expect-error the constructor is protected\nnew Singleton(\'x\')\nexport {}\n',
	40	+ ],
	41	+ [
	42	+ 'with a parameter property',
	43	+ 'export class Entity {\n protected constructor(public readonly id: number) {}\n}\n',
	44	+ 'protected constructor(id: number);',
	45	+ 'import { Entity } from \'./index\'\nexport class User extends Entity {\n constructor() { super(1) }\n}\nconst id: number = new User().id\n// @ts-expect-error the constructor is protected\nnew Entity(1)\nexport {}\n',
	46	+ ],
	47	+ [
	48	+ 'overloads',
	49	+ 'export class Point {\n protected constructor(x: number, y: number)\n protected constructor(xy: [number, number])\n protected constructor(a: any, b?: any) {}\n}\n',
	50	+ 'protected constructor(x: number, y: number);',
	51	+ 'import { Point } from \'./index\'\nexport class Origin extends Point {\n constructor() { super(0, 0) }\n}\n// @ts-expect-error the constructor is protected\nnew Point(0, 0)\nexport {}\n',
	52	+ ],
	53	+ ])('stays protected: %s', async (_label, code, constructor, consumer) => {
	54	+ const output = processCode(code)
	55	+ expect(output).toContain(constructor)
	56	+ expect(await checkConsumer(output, consumer)).toBe('')
	57	+ })
	58	+
	59	+ it.each([
	60	+ ['public modifier', 'export class C {\n public constructor(a: string) {}\n}\n'],
	61	+ ['a field named protected on the line before', 'export class C {\n protected\n constructor(a: string) { this.protected = a }\n}\n'],
	62	+ ['a line break inside a comment after protected', 'export class C {\n protected /*\n */ constructor(a: string) { this.protected = a }\n}\n'],
	63	+ ])('leaves a public constructor public: %s', async (_label, code) => {
	64	+ const output = processCode(code)
	65	+ expect(output).toContain(' constructor(a: string);')
	66	+ expect(output).not.toContain('protected constructor')
	67	+ expect(await checkConsumer(output, 'import { C } from \'./index\'\nnew C(\'x\')\nexport {}\n')).toBe('')
	68	+ })
	69	+})