feat: Node.js Middleware support (#3018)

Author: pieh

.gitignore

@@ -1,6 +1,7 @@
 node_modules/
 dist/
 .next
+.next-node-middleware
 edge-runtime/vendor
 # deno.json is ephemeral and generated for the purpose of vendoring remote modules in CI
 tools/deno/deno.json

edge-runtime/lib/cjs.test.ts

@@ -0,0 +1,106 @@
+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'
+
+type RequireResult = Record<string, string>
+
+const localRequire = createRequire(import.meta.url)
+const realRequireResult = localRequire('./fixture/cjs/entry.js') as RequireResult
+
+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 RequireResult
+
+const expectedVirtualRequireResult = {
+  entry: '/virtual-root/entry.js',
+
+  packageExportsConditionsExportedModule:
+    '/virtual-root/node_modules/package-exports-conditions/dist/exported-module.js',
+  packageExportsConditionsRoot:
+    '/virtual-root/node_modules/package-exports-conditions/root-export.js',
+  packageExportsConditionsWildcardModuleNoExt:
+    '/virtual-root/node_modules/package-exports-conditions/dist/wildcard/module.js',
+  packageExportsConditionsWildcardModuleWithExt:
+    '/virtual-root/node_modules/package-exports-conditions/dist/wildcard/module.js',
+  packageExportsExportedModule:
+    '/virtual-root/node_modules/package-exports/dist/exported-module.js',
+  packageExportsMainRoot: '/virtual-root/node_modules/package-exports-main/root-export.js',
+  packageExportsNotAllowedBecauseNotInExportMap: 'ERROR',
+  packageExportsRoot: '/virtual-root/node_modules/package-exports/root-export.js',
+  packageExportsSugarRoot: '/virtual-root/node_modules/package-exports-sugar/root-export.js',
+  packageExportsWildcardModuleNoExt:
+    '/virtual-root/node_modules/package-exports/dist/wildcard/module.js',
+  packageExportsWildcardModuleWithExt:
+    '/virtual-root/node_modules/package-exports/dist/wildcard/module.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/main.js',
+  packageMainInternalModule: '/virtual-root/node_modules/package-main/internal-module.js',
+} as RequireResult
+
+Deno.test('Virtual CJS Module loader matches real CJS Module loader', async (t) => {
+  // 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),
+    ]),
+  ]
+
+  function normalizeValue(value: string, basePath: string) {
+    if (value === 'ERROR') {
+      return value
+    }
+
+    return relative(basePath, value)
+  }
+
+  for (const key of allTheKeys) {
+    const virtualValue = virtualRequireResult[key]
+    const realValue = realRequireResult[key]
+
+    // values are filepaths or "ERROR" strings, "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(
+      normalizeValue(realValue, fixtureRootPath),
+      normalizeValue(virtualValue, virtualRootPath),
+    )
+  }
+})
+
+Deno.test('Virtual CJS Module loader matches expected results', async (t) => {
+  // 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)
+})