refactor: Extract deduplicate-wasm vite plugin to vite-plugins package

Author: rekmarks

packages/kernel-browser-runtime/vite.config.ts

@@ -1,7 +1,7 @@
 // eslint-disable-next-line spaced-comment
 /// <reference types="vitest" />
 
-import { jsTrustedPrelude } from '@ocap/vite-plugins';
+import { deduplicateAssets, jsTrustedPrelude } from '@ocap/vite-plugins';
 import type { PreludeRecord } from '@ocap/vite-plugins';
 import path from 'path';
 import { defineConfig } from 'vite';
@@ -110,28 +110,13 @@ export default defineConfig(({ mode }) => {
       // (It's probably related to the the file being conditionally imported in multiple places.)
       // To avoid bloating the bundle, we delete the duplicate files. Thankfully, these files are
       // extraneous because we don't hit their code paths in practice. (If we did, things would
-      // blow up spectacularly.)
-      {
-        name: 'deduplicate-sqlite-wasm',
-        enforce: 'post',
-        generateBundle(_, bundle) {
-          const extraneousAssets = Object.values(bundle).filter(
-            (assetOrChunk) =>
-              assetOrChunk.fileName.startsWith('sqlite3-') &&
-              !assetOrChunk.fileName.includes('sqlite3-opfs-async-proxy'),
-          );
-
-          if (extraneousAssets.length !== 2) {
-            throw new Error(
-              `Expected 2 extraneous sqlite3.wasm assets, got ${extraneousAssets.length}: ${extraneousAssets.map((asset) => asset.fileName).join(', ')}`,
-            );
-          }
-
-          for (const asset of extraneousAssets) {
-            delete bundle[asset.fileName];
-          }
-        },
-      },
+      // blow up.)
+      deduplicateAssets({
+        assetFilter: (fileName) =>
+          fileName.startsWith('sqlite3-') &&
+          !fileName.includes('sqlite3-opfs-async-proxy'),
+        expectedCount: 2,
+      }),
     ],
   };
 });

packages/vite-plugins/src/deduplicate-assets.ts

@@ -0,0 +1,40 @@
+import type { Plugin as VitePlugin } from 'vite';
+
+type Options = {
+  assetFilter: (fileName: string) => boolean;
+  expectedCount: number;
+};
+
+/**
+ * Vite plugin that deletes extraneous assets from the bundle.
+ *
+ * @param options - Options for the plugin
+ * @param options.assetFilter - A function that filters the assets to be deleted
+ * @param options.expectedCount - The expected number of assets to be deleted
+ * @throws If the number of extraneous assets is not equal to the expected count.
+ * @returns The Vite plugin.
+ */
+export function deduplicateAssets({
+  assetFilter,
+  expectedCount,
+}: Options): VitePlugin {
+  return {
+    name: 'ocap-kernel:deduplicate-assets',
+    enforce: 'post',
+    generateBundle(_, bundle) {
+      const extraneousAssets = Object.values(bundle).filter((assetOrChunk) =>
+        assetFilter(assetOrChunk.fileName),
+      );
+
+      if (extraneousAssets.length !== expectedCount) {
+        throw new Error(
+          `Expected ${expectedCount} extraneous assets, got ${extraneousAssets.length}: ${extraneousAssets.map((asset) => asset.fileName).join(', ')}`,
+        );
+      }
+
+      for (const asset of extraneousAssets) {
+        delete bundle[asset.fileName];
+      }
+    },
+  };
+}

packages/vite-plugins/src/extension-dev.ts

@@ -23,7 +23,7 @@ export function extensionDev({
   };
 
   return {
-    name: 'vite:extension-dev',
+    name: 'ocap-kernel:extension-dev',
 
     // This is called when the server starts
     async configureServer(server) {

packages/vite-plugins/src/index.test.ts

@@ -5,6 +5,7 @@ import * as indexModule from './index.ts';
 describe('index', () => {
   it('has the expected exports', () => {
     expect(Object.keys(indexModule).sort()).toStrictEqual([
+      'deduplicateAssets',
       'extensionDev',
       'htmlTrustedPrelude',
       'jsTrustedPrelude',

packages/vite-plugins/src/index.ts

@@ -1,3 +1,4 @@
+export * from './deduplicate-assets.ts';
 export * from './extension-dev.ts';
 export * from './html-trusted-prelude.ts';
 export * from './js-trusted-prelude.ts';