test: add virtual cjs test

Author: pieh

edge-runtime/lib/cjs.test.ts

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+import { createRequire } from 'node:module'
+import { join, dirname, relative } from 'node:path'
+import { fileURLToPath } from 'node:url'
+
+import { assertEquals } from 'https://deno.land/[email protected]/testing/asserts.ts'
+
+import { registerCJSModules } from './cjs.ts'
+
+Deno.test('Virtual CJS Module loader', async (t) => {
+  const localRequire = createRequire(import.meta.url)
+  const realRequireResult = localRequire('./fixture/cjs/entry.js') as Record<string, string>
+
+  const fixtureRoot = new URL('./fixture/cjs/', import.meta.url)
+  const virtualRoot = new URL('file:///virtual-root/index.mjs')
+
+  const fixtureRootPath = fileURLToPath(fixtureRoot)
+  const virtualRootPath = dirname(fileURLToPath(virtualRoot))
+
+  // load fixture into virtual CJS
+  const virtualModules = new Map<string, string>()
+  const decoder = new TextDecoder('utf-8')
+  async function addVirtualModulesFromDir(dir: string) {
+    const dirUrl = new URL('./' + dir, fixtureRoot)
+
+    for await (const dirEntry of Deno.readDir(dirUrl)) {
+      const relPath = join(dir, dirEntry.name)
+      if (dirEntry.isDirectory) {
+        await addVirtualModulesFromDir(relPath + '/')
+      } else if (dirEntry.isFile) {
+        const fileURL = new URL('./' + dirEntry.name, dirUrl)
+        virtualModules.set(relPath, decoder.decode(await Deno.readFile(fileURL)))
+      }
+    }
+  }
+
+  await addVirtualModulesFromDir('')
+  registerCJSModules(virtualRoot, virtualModules)
+
+  const virtualRequire = createRequire(virtualRoot)
+  const virtualRequireResult = virtualRequire('./entry.js') as Record<string, string>
+
+  const expectedVirtualRequireResult = {
+    entry: '/virtual-root/entry.js',
+    packageRoot: '/virtual-root/node_modules/package/index.js',
+    packageInternalModule: '/virtual-root/node_modules/package/internal-module.js',
+    packageMainRoot: '/virtual-root/node_modules/package-main/not-index.js',
+    packageMainInternalModule: '/virtual-root/node_modules/package-main/internal-module.js',
+  } as Record<string, string>
+
+  // make sure we collect all the possible keys to spot any cases of potentially missing keys in one of the objects
+  const allTheKeys = [
+    ...new Set([
+      ...Object.keys(expectedVirtualRequireResult),
+      ...Object.keys(realRequireResult),
+      ...Object.keys(virtualRequireResult),
+    ]),
+  ]
+
+  for (const key of allTheKeys) {
+    const virtualValue = virtualRequireResult[key]
+    const realValue = realRequireResult[key]
+
+    // values are filepaths, "real" require has actual file system paths, virtual ones has virtual paths starting with file:///virtual-root/
+    // we compare remaining paths to ensure same relative paths are reported indicating that resolution works the same in
+    // in real CommonJS and simulated one
+    assertEquals(relative(fixtureRootPath, realValue), relative(virtualRootPath, virtualValue))
+  }
+
+  // the main portion of testing functionality is in above assertions that compare real require and virtual one
+  // below is additional explicit assertion mostly to make sure that test setup is correct
+  assertEquals(virtualRequireResult, expectedVirtualRequireResult)
+})

edge-runtime/lib/fixture/cjs/.gitignore

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+!node_modules

edge-runtime/lib/fixture/cjs/entry.js

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+// package with no `main` or `exports`
+const packageRoot = require('package') // should resolve to `index.js`
+const packageInternalModule = require('package/internal-module') // should resolve to `internal-module.js`
+
+// package with `main`, but no `exports`
+const packageMainRoot = require('package-main') // should resolve to `not-index.js`
+const packageMainInternalModule = require('package-main/internal-module') // should resolve to `internal-module.js`
+
+module.exports = {
+  packageRoot,
+  packageInternalModule,
+  packageMainRoot,
+  packageMainInternalModule,
+  entry: __filename,
+}

edge-runtime/lib/fixture/cjs/node_modules/package-main/internal-module.js

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+{
+  "name": "cjs-fixture",
+  "private": true,
+  "type": "commonjs"
+}