fix(pnp): esm - support unflagged JSON modules

Author: merceyz

.pnp.cjs

@@ -0,0 +1,28 @@
+releases:
+ "@yarnpkg/cli": patch
+ "@yarnpkg/plugin-pnp": patch
+ "@yarnpkg/pnp": patch
+
+declined:
+ - "@yarnpkg/esbuild-plugin-pnp"
+ - "@yarnpkg/plugin-compat"
+ - "@yarnpkg/plugin-constraints"
+ - "@yarnpkg/plugin-dlx"
+ - "@yarnpkg/plugin-essentials"
+ - "@yarnpkg/plugin-init"
+ - "@yarnpkg/plugin-interactive-tools"
+ - "@yarnpkg/plugin-nm"
+ - "@yarnpkg/plugin-npm-cli"
+ - "@yarnpkg/plugin-pack"
+ - "@yarnpkg/plugin-patch"
+ - "@yarnpkg/plugin-pnpm"
+ - "@yarnpkg/plugin-stage"
+ - "@yarnpkg/plugin-typescript"
+ - "@yarnpkg/plugin-version"
+ - "@yarnpkg/plugin-workspace-tools"
+ - "@yarnpkg/builder"
+ - "@yarnpkg/core"
+ - "@yarnpkg/doctor"
+ - "@yarnpkg/nm"
+ - "@yarnpkg/pnpify"
+ - "@yarnpkg/sdks"

.yarn/versions/736d10bb.yml

@@ -65,6 +65,7 @@ The following changes only affect people writing Yarn plugins:
 ### Compatibility
 
 - Updates the PnP compatibility layer for TypeScript 4.8.1-rc
+- The ESM loader now supports unflagged JSON modules.
 
 ## 3.2.2
 

CHANGELOG.md

@@ -16,10 +16,12 @@
  "@yarnpkg/fslib": "workspace:^",
  "@yarnpkg/monorepo": "workspace:^",
  "@yarnpkg/parsers": "workspace:^",
+ "@yarnpkg/pnp": "workspace:^",
  "lodash": "^4.17.15",
  "pkg-tests-core": "workspace:^",
  "semver": "^7.1.2",
- "tar": "^6.0.5"
+ "tar": "^6.0.5",
+ "tslib": "^2.4.0"
  },
  "engines": {
  "node": ">=14.15.0"

packages/acceptance-tests/pkg-tests-specs/package.json

@@ -1,4 +1,5 @@
 import {Filename, ppath, xfs} from '@yarnpkg/fslib';
+import * as loaderFlags from '@yarnpkg/pnp/sources/esm-loader/loaderFlags';
 
 describe(`Plug'n'Play - ESM`, () => {
  test(
@@ -195,8 +196,8 @@ describe(`Plug'n'Play - ESM`, () => {
  ),
  );
 
- test(
- `it should not resolve JSON files`,
+ (loaderFlags.HAS_UNFLAGGED_JSON_MODULES === false ? test : test.skip)(
+ `it should not resolve JSON modules without --experimental-json-modules`,
  makeTemporaryEnv(
  {
  type: `module`,
@@ -218,6 +219,55 @@ describe(`Plug'n'Play - ESM`, () => {
  ),
  );
 
+ (loaderFlags.HAS_UNFLAGGED_JSON_MODULES ? test : test.skip)(
+ `it should not resolve JSON modules without an import assertion`,
+ makeTemporaryEnv(
+ {
+ type: `module`,
+ },
+ async ({path, run, source}) => {
+ await expect(run(`install`)).resolves.toMatchObject({code: 0});
+
+ await xfs.writeFilePromise(
+ ppath.join(path, `index.js` as Filename),
+ `import './foo.json';`,
+ );
+ await xfs.writeFilePromise(ppath.join(path, `foo.json` as Filename), `{"name": "foo"}`);
+
+ await expect(run(`node`, `./index.js`)).rejects.toMatchObject({
+ code: 1,
+ stderr: expect.stringContaining(`ERR_IMPORT_ASSERTION_TYPE_MISSING`),
+ });
+ },
+ ),
+ );
+
+ (loaderFlags.HAS_UNFLAGGED_JSON_MODULES ? test : test.skip)(
+ `it should resolve JSON modules with an import assertion`,
+ makeTemporaryEnv(
+ {
+ type: `module`,
+ },
+ async ({path, run, source}) => {
+ await expect(run(`install`)).resolves.toMatchObject({code: 0});
+
+ await xfs.writeFilePromise(
+ ppath.join(path, `index.js` as Filename),
+ `
+ import foo from './foo.json' assert { type: 'json' };
+ console.log(foo.name);
+ `,
+ );
+ await xfs.writeFilePromise(ppath.join(path, `foo.json` as Filename), `{"name": "foo"}`);
+
+ await expect(run(`node`, `./index.js`)).resolves.toMatchObject({
+ code: 0,
+ stdout: `foo\n`,
+ });
+ },
+ ),
+ );
+
  test(
  `it should respect exports`,
  makeTemporaryEnv(

packages/acceptance-tests/pkg-tests-specs/sources/pnp-esm.test.ts

@@ -1,12 +1,18 @@
-import fs from 'fs';
-import {fileURLToPath} from 'url';
+import fs  from 'fs';
+import {fileURLToPath}  from 'url';
 
-import * as loaderUtils from '../loaderUtils';
+import {HAS_JSON_IMPORT_ASSERTION_REQUIREMENT} from '../loaderFlags';
+import * as loaderUtils from '../loaderUtils';
 
 // The default `load` doesn't support reading from zip files
 export async function load(
  urlString: string,
- context: { format: string | null | undefined },
+ context: {
+ format: string | null | undefined;
+ importAssertions?: {
+ type?: 'json';
+ };
+ },
  nextLoad: typeof load,
 ): Promise<{ format: string, source: string, shortCircuit: boolean }> {
  const url = loaderUtils.tryParseURL(urlString);
@@ -19,6 +25,12 @@ export async function load(
  if (!format)
  return nextLoad(urlString, context, nextLoad);
 
+ if (HAS_JSON_IMPORT_ASSERTION_REQUIREMENT && format === `json` && context.importAssertions?.type !== `json`) {
+ const err = new TypeError(`[ERR_IMPORT_ASSERTION_TYPE_MISSING]: Module "${urlString}" needs an import assertion of type "json"`) as TypeError & { code: string };
+ err.code = `ERR_IMPORT_ASSERTION_TYPE_MISSING`;
+ throw err;
+ }
+
  return {
  format,
  source: await fs.promises.readFile(filePath, `utf8`),

packages/yarnpkg-pnp/sources/esm-loader/built-loader.js

@@ -2,14 +2,10 @@ import {getFormat as getFormatHook} from './hooks/getFormat';
 import {getSource as getSourceHook} from './hooks/getSource';
 import {load as loadHook} from './hooks/load';
 import {resolve as resolveHook} from './hooks/resolve';
+import {HAS_CONSOLIDATED_HOOKS} from './loaderFlags';
 import './fspatch';
 
-const [major, minor] = process.versions.node.split(`.`).map(value => parseInt(value, 10));
-
-// The hooks were consolidated in https://github.com/nodejs/node/pull/37468
-const hasConsolidatedHooks = major > 16 || (major === 16 && minor >= 12);
-
 export const resolve = resolveHook;
-export const getFormat = hasConsolidatedHooks ? undefined : getFormatHook;
-export const getSource = hasConsolidatedHooks ? undefined : getSourceHook;
-export const load = hasConsolidatedHooks ? loadHook : undefined;
+export const getFormat = HAS_CONSOLIDATED_HOOKS ? undefined : getFormatHook;
+export const getSource = HAS_CONSOLIDATED_HOOKS ? undefined : getSourceHook;
+export const load = HAS_CONSOLIDATED_HOOKS ? loadHook : undefined;

packages/yarnpkg-pnp/sources/esm-loader/hooks/load.ts

@@ -0,0 +1,10 @@
+const [major, minor] = process.versions.node.split(`.`).map(value => parseInt(value, 10));
+
+// The hooks were consolidated in https://github.com/nodejs/node/pull/37468
+export const HAS_CONSOLIDATED_HOOKS = major > 16 || (major === 16 && minor >= 12);
+
+// JSON modules were unflagged in https://github.com/nodejs/node/pull/41736
+export const HAS_UNFLAGGED_JSON_MODULES = major > 17 || (major === 17 && minor >= 5) || (major === 16 && minor >= 15);
+
+// JSON modules requires import assertions after https://github.com/nodejs/node/pull/40250
+export const HAS_JSON_IMPORT_ASSERTION_REQUIREMENT = major > 17 || (major === 17 && minor >= 1) || (major === 16 && minor > 14);

packages/yarnpkg-pnp/sources/esm-loader/loader.ts

@@ -1,9 +1,11 @@
-import {NativePath} from '@yarnpkg/fslib';
-import fs from 'fs';
-import path from 'path';
-import {URL} from 'url';
+import {NativePath}  from '@yarnpkg/fslib';
+import fs  from 'fs';
+import path  from 'path';
+import {URL}  from 'url';
 
-import * as nodeUtils from '../loader/nodeUtils';
+import * as nodeUtils from '../loader/nodeUtils';
+
+import {HAS_UNFLAGGED_JSON_MODULES} from './loaderFlags';
 
 export async function tryReadFile(path: NativePath): Promise<string | null> {
  try {
@@ -48,6 +50,9 @@ export function getFileFormat(filepath: string): string | null {
  );
  }
  case `.json`: {
+ if (HAS_UNFLAGGED_JSON_MODULES)
+ return `json`;
+
  // TODO: Enable if --experimental-json-modules is present
  // Waiting on https://github.com/nodejs/node/issues/36935
  throw new Error(