More copy-pasting from node's source code; add test coverage for reading package.json exports field

Author: cspotcode

.gitignore

@@ -1,4 +1,5 @@
-node_modules/
+/node_modules/
+/tests/node_modules/
 .nyc_output/
 coverage/
 .DS_Store

dist-raw/node-cjs-loader-utils.js

@@ -3,12 +3,13 @@
 // Each function and variable below must have a comment linking to the source in node's github repo.
 
 const path = require('path');
-const {internalModuleReadJSON} = require('./node-internal-fs');
+const packageJsonReader = require('./node-package-json-reader');
+const {JSONParse} = require('./node-primordials');
 
 module.exports.assertScriptCanLoadAsCJSImpl = assertScriptCanLoadAsCJSImpl;
 
 // copied from Module._extensions['.js']
-// https://github.com/nodejs/node/blob/2d5d77306f6dff9110c1f77fefab25f973415770/lib/internal/modules/cjs/loader.js#L1211-L1217
+// https://github.com/nodejs/node/blob/v15.3.0/lib/internal/modules/cjs/loader.js#L1113-L1120
 function assertScriptCanLoadAsCJSImpl(filename) {
   const pkg = readPackageScope(filename);
   // Function require shouldn't be used in ES modules.
@@ -41,31 +42,27 @@ function readPackageScope(checkPath) {
 // Copied from https://github.com/nodejs/node/blob/2d5d77306f6dff9110c1f77fefab25f973415770/lib/internal/modules/cjs/loader.js#L249
 const packageJsonCache = new Map();
 
-// Copied from https://github.com/nodejs/node/blob/2d5d77306f6dff9110c1f77fefab25f973415770/lib/internal/modules/cjs/loader.js#L251-L283
+// Copied from https://github.com/nodejs/node/blob/v15.3.0/lib/internal/modules/cjs/loader.js#L275-L304
 function readPackage(requestPath) {
   const jsonPath = path.resolve(requestPath, 'package.json');
 
   const existing = packageJsonCache.get(jsonPath);
   if (existing !== undefined) return existing;
 
-  const json = internalModuleReadJSON(path.toNamespacedPath(jsonPath));
+  const result = packageJsonReader.read(jsonPath);
+  const json = result.containsKeys === false ? '{}' : result.string;
   if (json === undefined) {
     packageJsonCache.set(jsonPath, false);
     return false;
   }
 
-  // TODO Related to `--experimental-policy`?  Disabling for now
-  // if (manifest) {
-  //   const jsonURL = pathToFileURL(jsonPath);
-  //   manifest.assertIntegrity(jsonURL, json);
-  // }
-
   try {
-    const parsed = JSON.parse(json);
+    const parsed = JSONParse(json);
     const filtered = {
       name: parsed.name,
       main: parsed.main,
       exports: parsed.exports,
+      imports: parsed.imports,
       type: parsed.type
     };
     packageJsonCache.set(jsonPath, filtered);

dist-raw/node-internal-fs.js

@@ -1,14 +1,20 @@
 const fs = require('fs');
 
 // In node's core, this is implemented in C
-// https://github.com/nodejs/node/blob/e9f293750760d59243020d0376edf242c9a26b67/src/node_file.cc#L845-L939
+// https://github.com/nodejs/node/blob/v15.3.0/src/node_file.cc#L891-L985
 function internalModuleReadJSON(path) {
+  let string
   try {
-    return fs.readFileSync(path, 'utf8')
+    string = fs.readFileSync(path, 'utf8')
   } catch (e) {
-    if (e.code === 'ENOENT') return undefined
+    if (e.code === 'ENOENT') return []
     throw e
   }
+  // Node's implementation checks for the presence of relevant keys: main, name, type, exports, imports
+  // Node does this for performance to skip unnecessary parsing.
+  // This would slow us down and, based on our usage, we can skip it.
+  const containsKeys = true
+  return [string, containsKeys]
 }
 
 module.exports = {

dist-raw/node-package-json-reader.js

@@ -11,8 +11,8 @@ const cache = new SafeMap();
 let manifest;
 
 /**
- *
  * @param {string} jsonPath
+ * @return {[string, boolean]}
  */
 function read(jsonPath) {
   if (cache.has(jsonPath)) {

package.json

@@ -50,7 +50,7 @@
     "build-pack": "node ./scripts/build-pack.js",
     "test-spec": "mocha dist/**/*.spec.js -R spec --bail",
     "test-cov": "nyc mocha -- \"dist/**/*.spec.js\" -R spec --bail",
-    "test": "npm run build && npm run lint && npm run test-cov",
+    "test": "npm run build && npm run lint && npm run test-cov --",
     "coverage-report": "nyc report --reporter=lcov",
     "prepare": "npm run build-nopack"
   },

src/index.spec.ts

@@ -860,7 +860,7 @@ describe('ts-node', function () {
       it('should compile and execute as ESM', (done) => {
         exec(`${cmd} index.ts`, { cwd: join(__dirname, '../tests/esm') }, function (err, stdout) {
           expect(err).to.equal(null)
-          expect(stdout).to.equal('foo bar baz biff\n')
+          expect(stdout).to.equal('foo bar baz biff libfoo\n')
 
           return done()
         })
@@ -883,15 +883,15 @@ describe('ts-node', function () {
         it('via --experimental-specifier-resolution', (done) => {
           exec(`${cmd} --experimental-specifier-resolution=node index.ts`, { cwd: join(__dirname, '../tests/esm-node-resolver') }, function (err, stdout) {
             expect(err).to.equal(null)
-            expect(stdout).to.equal('foo bar baz biff\n')
+            expect(stdout).to.equal('foo bar baz biff libfoo\n')
 
             return done()
           })
         })
         it('via --es-module-specifier-resolution alias', (done) => {
           exec(`${cmd} --experimental-modules --es-module-specifier-resolution=node index.ts`, { cwd: join(__dirname, '../tests/esm-node-resolver') }, function (err, stdout) {
             expect(err).to.equal(null)
-            expect(stdout).to.equal('foo bar baz biff\n')
+            expect(stdout).to.equal('foo bar baz biff libfoo\n')
 
             return done()
           })
@@ -905,7 +905,7 @@ describe('ts-node', function () {
             }
           }, function (err, stdout) {
             expect(err).to.equal(null)
-            expect(stdout).to.equal('foo bar baz biff\n')
+            expect(stdout).to.equal('foo bar baz biff libfoo\n')
 
             return done()
           })

tests/esm-node-resolver/index.ts

@@ -2,7 +2,8 @@ import {foo} from './foo'
 import {bar} from './bar'
 import {baz} from './baz'
 import {biff} from './biff'
+import {libfoo} from 'libfoo'
 
 if(typeof module !== 'undefined') throw new Error('module should not exist in ESM')
 
-console.log(`${foo} ${bar} ${baz} ${biff}`)
+console.log(`${foo} ${bar} ${baz} ${biff} ${libfoo}`)

tests/esm-node-resolver/node_modules/libfoo/entrypoint.js

@@ -2,11 +2,12 @@ import {foo} from './foo.js'
 import {bar} from './bar.js'
 import {baz} from './baz.js'
 import {biff} from './biff.js'
+import {libfoo} from 'libfoo'
 
 // Test import builtin modules
 import {readFileSync} from 'fs';
 if(typeof readFileSync !== 'function') throw new Error('failed to import builtin module')
 
 if(typeof module !== 'undefined') throw new Error('module should not exist in ESM')
 
-console.log(`${foo} ${bar} ${baz} ${biff}`)
+console.log(`${foo} ${bar} ${baz} ${biff} ${libfoo}`)

tests/esm-node-resolver/node_modules/libfoo/index.d.ts

@@ -2,6 +2,7 @@
   "compilerOptions": {
     "module": "ESNext",
     "allowJs": true,
-    "jsx": "react"
+    "jsx": "react",
+    "moduleResolution": "node"
   }
 }