Add metro plugin

packages/knip/fixtures/plugins/metro/metro.config.js

@@ -0,0 +1,8 @@
+module.exports = {
+  projectRoot: './src/app',
+  transformer: {
+    minifierPath: 'metro-minify-esbuild',
+    assetPlugins: ["expo-asset/tools/hashAssetFiles"],
+    babelTransformerPath: 'react-native-svg-transformer'
+  },
+};

packages/knip/fixtures/plugins/metro/package.json

@@ -0,0 +1,13 @@
+{
+  "name": "@fixtures/metro",
+  "version": "*",
+  "dependencies": {
+    "expo-asset": "*",
+    "react": "*",
+    "react-native": "*",
+    "react-native-svg-transformer": "*"
+  },
+  "metro": {
+    "transformerPath": "./custom-metro-transformer.js"
+  }
+}

packages/knip/schema.json

@@ -400,6 +400,10 @@
           "title": "markdownlint plugin configuration (https://knip.dev/reference/plugins/markdownlint)",
           "$ref": "#/definitions/plugin"
         },
+        "metro": {
+          "title": "metro plugin configuration (https://knip.dev/reference/plugins/metro)",
+          "$ref": "#/definitions/plugin"
+        },
         "mocha": {
           "title": "Mocha plugin configuration (https://knip.dev/reference/plugins/mocha)",
           "$ref": "#/definitions/plugin"

packages/knip/src/plugins/index.ts

@@ -30,6 +30,7 @@ import { default as linthtml } from './linthtml/index.js';
 import { default as lockfileLint } from './lockfile-lint/index.js';
 import { default as lostPixel } from './lost-pixel/index.js';
 import { default as markdownlint } from './markdownlint/index.js';
+import { default as metro } from './metro/index.js';
 import { default as mocha } from './mocha/index.js';
 import { default as moonrepo } from './moonrepo/index.js';
 import { default as msw } from './msw/index.js';
@@ -121,6 +122,7 @@ export const Plugins = {
   'lockfile-lint': lockfileLint,
   'lost-pixel': lostPixel,
   markdownlint,
+  metro,
   mocha,
   moonrepo,
   msw,

packages/knip/src/plugins/metro/index.ts

@@ -0,0 +1,47 @@
+import type { IsPluginEnabled, Plugin, ResolveConfig, ResolveEntryPaths } from '../../types/config.js';
+import { toDeferResolve, toProductionEntry } from '../../util/input.js';
+import { join } from '../../util/path.js';
+import { hasDependency } from '../../util/plugin.js';
+import type { PluginConfig } from './types.js';
+
+// https://metrobundler.dev/docs/configuration
+
+const title = 'Metro';
+
+const enablers = ['metro', 'react-native'];
+
+const isEnabled: IsPluginEnabled = options => hasDependency(options.dependencies, enablers);
+
+const packageJsonPath = 'metro';
+
+const config: string[] = ['metro.config.{js,cjs,json}', 'package.json'];
+
+const resolveEntryPaths: ResolveEntryPaths<PluginConfig> = async config => {
+  if (!config.projectRoot) return [];
+
+  const entryFilePattern = 'index.{js,jsx,ts,tsx}';
+  const entryFilePath = join(config.projectRoot, entryFilePattern);
+  return [toProductionEntry(entryFilePath)];
+};
+
+const resolveConfig: ResolveConfig<PluginConfig> = async config => {
+  const { transformerPath, transformer } = config;
+  const inputs: string[] = [];
+
+  if (transformerPath) inputs.push(transformerPath);
+  if (transformer?.assetPlugins) inputs.push(...transformer.assetPlugins);
+  if (transformer?.minifierPath) inputs.push(transformer.minifierPath);
+  if (transformer?.babelTransformerPath) inputs.push(transformer.babelTransformerPath);
+
+  return [...inputs].map(toDeferResolve);
+};
+
+export default {
+  title,
+  enablers,
+  isEnabled,
+  packageJsonPath,
+  config,
+  resolveEntryPaths,
+  resolveConfig,
+} satisfies Plugin;

packages/knip/src/plugins/metro/types.ts

@@ -0,0 +1,11 @@
+// https://github.com/facebook/metro/blob/main/packages/metro-config/types/configTypes.d.ts
+
+export type PluginConfig = {
+  projectRoot?: string;
+  transformerPath?: string;
+  transformer?: {
+    minifierPath?: string;
+    assetPlugins?: string[];
+    babelTransformerPath?: string;
+  };
+};

packages/knip/src/schema/plugins.ts

@@ -44,6 +44,7 @@ export const pluginsSchema = z.object({
   'lockfile-lint': pluginSchema,
   'lost-pixel': pluginSchema,
   markdownlint: pluginSchema,
+  metro: pluginSchema,
   mocha: pluginSchema,
   moonrepo: pluginSchema,
   msw: pluginSchema,

packages/knip/src/types/PluginNames.ts

@@ -31,6 +31,7 @@ export type PluginName =
   | 'lockfile-lint'
   | 'lost-pixel'
   | 'markdownlint'
+  | 'metro'
   | 'mocha'
   | 'moonrepo'
   | 'msw'
@@ -122,6 +123,7 @@ export const pluginNames = [
   'lockfile-lint',
   'lost-pixel',
   'markdownlint',
+  'metro',
   'mocha',
   'moonrepo',
   'msw',

packages/knip/test/plugins/metro.test.ts

@@ -0,0 +1,29 @@
+import { test } from 'bun:test';
+import assert from 'node:assert/strict';
+import { main } from '../../src/index.js';
+import { resolve } from '../../src/util/path.js';
+import baseArguments from '../helpers/baseArguments.js';
+import baseCounters from '../helpers/baseCounters.js';
+
+const cwd = resolve('fixtures/plugins/metro');
+
+test('Find dependencies with the Metro plugin', async () => {
+  const { issues, counters } = await main({
+    ...baseArguments,
+    cwd,
+  });
+
+  assert(issues.dependencies['package.json']['react']);
+  assert(issues.dependencies['package.json']['react-native']);
+
+  assert(issues.unresolved['metro.config.js']['metro-minify-esbuild']);
+  assert(issues.unresolved['package.json']['./custom-metro-transformer.js']);
+
+  assert.deepEqual(counters, {
+    ...baseCounters,
+    dependencies: 2,
+    unresolved: 2,
+    processed: 2,
+    total: 2,
+  });
+});