fix(compartment-map): Restore test fixture maker and support for exit…

… modules from archives

packages/compartment-mapper/src/archive.js

@@ -154,7 +154,8 @@ const addSourcesToArchive = async (archive, sources) => {
  * @returns {Promise<Uint8Array>}
  */
 export const makeArchive = async (powers, moduleLocation, options) => {
-  const { moduleTransforms, modules = {}, dev = false } = options || {};
+  const { moduleTransforms, modules: exitModules = {}, dev = false } =
+    options || {};
   const { read } = unpackReadPowers(powers);
   const {
     packageLocation,
@@ -191,15 +192,17 @@ export const makeArchive = async (powers, moduleLocation, options) => {
     packageLocation,
     sources,
     compartments,
+    exitModules,
   );
 
   // Induce importHook to record all the necessary modules to import the given module specifier.
   const compartment = assemble(compartmentMap, {
     resolve,
-    modules,
+    modules: exitModules,
     makeImportHook,
     moduleTransforms,
     parserForLanguage,
+    archiveOnly: true,
   });
   await compartment.load(entryModuleSpecifier);
 

packages/compartment-mapper/src/assemble.js

@@ -16,6 +16,29 @@ const { entries, fromEntries, freeze } = Object;
 const { hasOwnProperty } = Object.prototype;
 const { apply } = Reflect;
 
+const inertStaticModuleRecord = {
+  imports: [],
+  exports: [],
+  execute() {
+    throw new Error(
+      `Assertion failed: compartment graphs built for archives cannot be initialized`,
+    );
+  },
+};
+
+const inertModuleNamespace = new Compartment(
+  {},
+  {},
+  {
+    resolveHook() {
+      return '';
+    },
+    async importHook() {
+      return inertStaticModuleRecord;
+    },
+  },
+).module('');
+
 const defaultCompartment = Compartment;
 
 // q, as in quote, for strings in error messages.
@@ -155,6 +178,7 @@ const trimModuleSpecifierPrefix = (moduleSpecifier, prefix) => {
  * @param {Record<string, ModuleDescriptor>} moduleDescriptors
  * @param {Record<string, ModuleDescriptor>} scopeDescriptors
  * @param {Record<string, string>} exitModules
+ * @param {boolean} archiveOnly
  * @returns {ModuleMapHook | undefined}
  */
 const makeModuleMapHook = (
@@ -163,6 +187,7 @@ const makeModuleMapHook = (
   moduleDescriptors,
   scopeDescriptors,
   exitModules,
+  archiveOnly,
 ) => {
   /**
    * @param {string} moduleSpecifier
@@ -177,10 +202,10 @@ const makeModuleMapHook = (
         exit,
       } = moduleDescriptor;
       if (exit !== undefined) {
-        // TODO Currenly, only the entry package can connect to built-in modules.
+        // TODO Currenly, every package can connect to built-in modules.
         // Policies should be able to allow third-party modules to exit to
-        // built-ins, or have built-ins subverted by modules from specific
-        // compartments.
+        // built-ins explicitly, or have built-ins subverted by modules from
+        // specific compartments.
         const module = exitModules[exit];
         if (module === undefined) {
           throw new Error(
@@ -189,7 +214,11 @@ const makeModuleMapHook = (
             )}, may be missing from ${compartmentName} package.json`,
           );
         }
-        return module;
+        if (archiveOnly) {
+          return inertModuleNamespace;
+        } else {
+          return module;
+        }
       }
       if (foreignModuleSpecifier !== undefined) {
         const foreignCompartment = compartments[foreignCompartmentName];
@@ -202,6 +231,17 @@ const makeModuleMapHook = (
         }
         return foreignCompartment.module(foreignModuleSpecifier);
       }
+    } else if (has(exitModules, moduleSpecifier)) {
+      // When linking off the filesystem as with `importLocation`,
+      // there isn't a module descriptor for every module.
+      // TODO grant access to built-in modules contingent on a policy in the
+      // application's entry package descriptor.
+      moduleDescriptors[moduleSpecifier] = { exit: moduleSpecifier };
+      if (archiveOnly) {
+        return inertModuleNamespace;
+      } else {
+        return exitModules[moduleSpecifier];
+      }
     }
 
     // Search for a scope that shares a prefix with the requested module
@@ -281,6 +321,7 @@ export const link = (
     moduleTransforms = {},
     __shimTransforms__ = [],
     modules: exitModules = {},
+    archiveOnly = false,
     Compartment = defaultCompartment,
   },
 ) => {
@@ -318,12 +359,13 @@ export const link = (
       modules,
       scopes,
       exitModules,
+      archiveOnly,
     );
     const resolveHook = resolve;
     resolvers[compartmentName] = resolve;
 
     // TODO also thread powers selectively.
-    const compartment = new Compartment(globals, exitModules, {
+    const compartment = new Compartment(globals, undefined, {
       resolveHook,
       importHook,
       moduleMapHook,

packages/compartment-mapper/src/types.js

@@ -189,6 +189,7 @@ export const moduleJSDocTypes = true;
  * @property {AssembleImportHook} makeImportHook
  * @property {ParserForLanguage} parserForLanguage
  * @property {ModuleTransforms} [moduleTransforms]
+ * @property {boolean} [archiveOnly]
  */
 
 /**
@@ -235,6 +236,6 @@ export const moduleJSDocTypes = true;
 /**
  * @typedef {Object} ArchiveOptions
  * @property {ModuleTransforms} [moduleTransforms]
- * @property {Record<string, any>} [modules]
+ * @property {Record<string, never>} [modules]
  * @property {boolean} [dev]
  */

packages/compartment-mapper/test/app.agar-make.js

@@ -6,6 +6,8 @@
 // The archive may need to be regenerated if the test fixture and assertions
 // have been changed.
 
+/* global process */
+
 import 'ses';
 import fs from 'fs';
 import { writeArchive } from '../archive.js';
@@ -20,4 +22,14 @@ const fixture = new URL(
 ).toString();
 const archiveFixture = new URL('app.agar', import.meta.url).toString();
 
-writeArchive(write, readPowers, archiveFixture, fixture);
+const mitt = err =>
+  process.nextTick(() => {
+    throw err;
+  });
+
+writeArchive(write, readPowers, archiveFixture, fixture, {
+  dev: true,
+  modules: {
+    builtin: true,
+  },
+}).catch(mitt);

packages/compartment-mapper/test/test-main.js

@@ -187,7 +187,7 @@ test('writeArchive / loadArchive', async t => {
   };
 
   await writeArchive(fakeWrite, readPowers, 'app.agar', fixture, {
-    modules,
+    modules: { builtin: true },
     dev: true,
   });
   const application = await loadArchive(fakeRead, 'app.agar');