feat(valid-exports): add new rule for validating exports (#1220)

<!-- 👋 Hi, thanks for sending a PR to eslint-plugin-package-json! 🗂 Please fill out all fields below and make sure each item is true and [x] checked. Otherwise we may not be able to review your PR. --> ## PR Checklist - [x] Addresses an existing open issue: fixes #1033 - [x] That issue was marked as [`status: accepting prs`](https://github.com/JoshuaKGoldberg/eslint-plugin-package-json/issues?q=is%3Aopen+is%3Aissue+label%3A%22status%3A+accepting+prs%22) - [x] Steps in [CONTRIBUTING.md](https://github.com/JoshuaKGoldberg/eslint-plugin-package-json/blob/main/.github/CONTRIBUTING.md) were taken ## Overview This change adds a new `valid-exports` rule that uses `exports` from package-json-validator to identify errors. It's included in the `recommended` config.

Author: michaelfaith

.vscode/settings.json

@@ -14,5 +14,6 @@
 "yaml"
 ],
 "eslint.rules.customizations": [{ "rule": "*", "severity": "warn" }],
-"typescript.tsdk": "node_modules/typescript/lib"
+"typescript.tsdk": "node_modules/typescript/lib",
+"npm.packageManager": "pnpm"
 }

README.md

@@ -185,6 +185,7 @@ The default settings don't conflict, and Prettier plugins can quickly fix up ord
 | [valid-dependencies](docs/rules/valid-dependencies.md) | Enforce that the `dependencies` property is valid. | ✔️ ✅ | | | |
 | [valid-description](docs/rules/valid-description.md) | Enforce that the `description` property is valid. | ✔️ ✅ | | | |
 | [valid-devDependencies](docs/rules/valid-devDependencies.md) | Enforce that the `devDependencies` property is valid. | ✔️ ✅ | | | |
+| [valid-exports](docs/rules/valid-exports.md) | Enforce that the `exports` property is valid. | ✔️ ✅ | | | |
 | [valid-license](docs/rules/valid-license.md) | Enforce that the `license` property is valid. | ✔️ ✅ | | | |
 | [valid-local-dependency](docs/rules/valid-local-dependency.md) | Checks existence of local dependencies in the package.json | | | | ❌ |
 | [valid-name](docs/rules/valid-name.md) | Enforce that package names are valid npm package names | ✔️ ✅ | | | |

docs/rules/valid-exports.md

@@ -0,0 +1,55 @@
+# valid-exports
+
+💼 This rule is enabled in the following configs: ✔️ `legacy-recommended`, ✅ `recommended`.
+
+<!-- end auto-generated rule header -->
+
+The rule checks that, if present, the `exports` property is a validated according the following criteria:
+
+- It should be of type `string` or `object`.
+- If it's a `string`, it should be a path to an entry point.
+- If it's an export condition object, its properties should have values that are either a path to an entry point, or another exports condition object.
+
+Example of **incorrect** code for this rule:
+
+```json
+{
+"exports": {
+"import": true
+}
+}
+```
+
+Example of **correct** code for this rule:
+
+```json
+{
+"exports": "./index.js"
+}
+```
+
+```json
+{
+"exports": {
+".": "./index.js",
+"./secondary": "./secondary.js"
+}
+}
+```
+
+```json
+{
+"exports": {
+".": {
+"import": {
+"types": "./esm/index.d.mts",
+"default": "./esm/index.mjs"
+},
+"require": {
+"types": "./cjs/index.d.cts",
+"default": "./cjs/index.cjs"
+}
+}
+}
+}
+```

package.json

@@ -49,7 +49,7 @@
 "detect-indent": "^7.0.1",
 "detect-newline": "^4.0.1",
 "eslint-fix-utils": "~0.4.0",
-"package-json-validator": "~0.27.0",
+"package-json-validator": "~0.29.0",
 "semver": "^7.5.4",
 "sort-object-keys": "^1.1.3",
 "sort-package-json": "^3.3.0",

pnpm-lock.yaml

@@ -5,6 +5,7 @@ import {
 validateCpu,
 validateDependencies,
 validateDescription,
+validateExports,
 validateLicense,
 validateScripts,
 validateType,
@@ -36,6 +37,7 @@ const properties = [
 ["dependencies", validateDependencies],
 ["description", validateDescription],
 ["devDependencies", validateDependencies],
+["exports", validateExports],
 ["license", validateLicense],
 ["optionalDependencies", validateDependencies],
 ["peerDependencies", validateDependencies],

src/rules/valid-properties.ts

@@ -0,0 +1,113 @@
+import { rules } from "../../rules/valid-properties.ts";
+import { ruleTester } from "./ruleTester.ts";
+
+ruleTester.run("valid-exports", rules["valid-exports"], {
+invalid: [
+{
+code: `{
+"exports": null
+}
+`,
+errors: [
+{
+data: {
+errors: "the field is `null`, but should be an `object` or `string`",
+},
+messageId: "validationError",
+},
+],
+},
+{
+code: `{
+"exports": 123
+}
+`,
+errors: [
+{
+data: {
+errors: "the type should be `object` or `string`, not `number`",
+},
+messageId: "validationError",
+},
+],
+},
+{
+code: `{
+"exports": ""
+}
+`,
+errors: [
+{
+data: {
+errors: "the value is empty, but should be an entry point path",
+},
+messageId: "validationError",
+},
+],
+},
+{
+code: `{
+"exports": { "./invalid": 123 }
+}
+`,
+errors: [
+{
+data: {
+errors: 'the value of "./invalid" should be either an entry point path or an object of export conditions',
+},
+messageId: "validationError",
+},
+],
+},
+{
+code: `{
+"exports": { "./invalid": "" }
+}
+`,
+errors: [
+{
+data: {
+errors: 'the value of "./invalid" is empty, but should be an entry point path',
+},
+messageId: "validationError",
+},
+],
+},
+{
+code: `{
+"exports": { "": "invalid" }
+}
+`,
+errors: [
+{
+data: {
+errors: "property 0 has an empty key, but should be an export condition",
+},
+messageId: "validationError",
+},
+],
+},
+{
+code: `{
+"exports": { "": "invalid", " ": "invalid" }
+}
+`,
+errors: [
+{
+data: {
+errors: `
+ - property 0 has an empty key, but should be an export condition
+ - property 1 has an empty key, but should be an export condition`,
+},
+messageId: "validationError",
+},
+],
+},
+],
+valid: [
+"{}",
+`{ "exports": "./index.js" }`,
+`{ "exports": { ".": "./index.js", "./secondary": "./secondary.js" } }`,
+`{ "exports": { ".": { "types": "./index.d.ts", "default": "./index.js" } } }`,
+],
+});