refactor(metro-resolver-symlinks): reuse `findMetroPath` (#2610)

.changeset/tough-owls-collect.md

@@ -0,0 +1,5 @@
+---
+"@rnx-kit/metro-resolver-symlinks": patch
+---
+
+Reuse `findMetroPath` from `@rnx-kit/tools-react-native`

packages/metro-resolver-symlinks/src/helper.ts

@@ -1,7 +1,5 @@
-import {
-  findPackageDependencyDir,
-  readPackage,
-} from "@rnx-kit/tools-node/package";
+import { findPackageDependencyDir } from "@rnx-kit/tools-node/package";
+import { findMetroPath } from "@rnx-kit/tools-react-native/metro";
 
 export function resolveFrom(
   moduleName: string,
@@ -13,31 +11,6 @@ export function resolveFrom(
   });
 }
 
-export function ensureResolveFrom(
-  moduleName: string,
-  startDir: string
-): string {
-  const p = resolveFrom(moduleName, startDir);
-  if (!p) {
-    throw new Error(`Cannot find module '${moduleName}'`);
-  }
-  return p;
-}
-
-/**
- * Returns the directory in which `metro` and its dependencies were installed.
- * @param fromDir The directory to start searching from
- */
-export function getMetroSearchPath(fromDir = process.cwd()): string {
-  const rnPath = ensureResolveFrom("react-native", fromDir);
-  const rncliPath = ensureResolveFrom("@react-native-community/cli", rnPath);
-
-  const { dependencies = {} } = readPackage(rncliPath);
-  return "@react-native-community/cli-plugin-metro" in dependencies
-    ? ensureResolveFrom("@react-native-community/cli-plugin-metro", rncliPath)
-    : rncliPath;
-}
-
 /**
  * Imports specified module starting from the installation directory of the
  * currently used `metro` version.
@@ -49,13 +22,22 @@ export function requireModuleFromMetro<R = unknown>(
   moduleName: string,
   fromDir = process.cwd()
 ): R {
-  try {
-    const startDir = getMetroSearchPath(fromDir);
-    const metroModulePath = ensureResolveFrom(moduleName, startDir);
-    return require(metroModulePath);
-  } catch (_) {
+  const startDir = findMetroPath(fromDir);
+  if (!startDir) {
+    throw new Error("Cannot find module 'metro'");
+  }
+
+  const modulePath = resolveFrom(moduleName, startDir);
+  if (!modulePath) {
     throw new Error(
-      `Cannot find module '${moduleName}'. This probably means that '@rnx-kit/metro-resolver-symlinks' is not compatible with the version of 'metro' that you are currently using. Please update to the latest version and try again. If the issue still persists after the update, please file a bug at https://github.com/microsoft/rnx-kit/issues.`
+      `Cannot find module '${moduleName}'. This probably means that ` +
+        "'@rnx-kit/metro-resolver-symlinks' is not compatible with the " +
+        "version of 'metro' that you are currently using. Please update to " +
+        "the latest version and try again. If the issue still persists after " +
+        "the update, please file a bug at " +
+        "https://github.com/microsoft/rnx-kit/issues."
     );
   }
+
+  return require(modulePath);
 }

packages/metro-resolver-symlinks/src/utils/patchMetro.ts

@@ -1,6 +1,6 @@
+import { findMetroPath } from "@rnx-kit/tools-react-native/metro";
 import * as fs from "fs";
 import * as path from "path";
-import { ensureResolveFrom, getMetroSearchPath } from "../helper";
 import type { Options } from "../types";
 
 function fileExists(path: string): boolean {
@@ -9,7 +9,7 @@ function fileExists(path: string): boolean {
 }
 
 function importMetroModule(path: string) {
-  const metroPath = ensureResolveFrom("metro", getMetroSearchPath());
+  const metroPath = findMetroPath();
   const modulePath = metroPath + path;
   try {
     return require(modulePath);

packages/metro-resolver-symlinks/test/__fixtures__/metro-resolver-duplicates/node_modules/@react-native-community/cli/node_modules/metro/index.js

@@ -0,0 +1 @@
+exports.resolve = () => __dirname;

packages/metro-resolver-symlinks/test/__fixtures__/metro-resolver-duplicates/node_modules/@react-native-community/cli/node_modules/metro/package.json

@@ -0,0 +1,5 @@
+{
+  "name": "metro",
+  "version": "1.0.0",
+  "main": "index.js"
+}

packages/metro-resolver-symlinks/test/__fixtures__/pnpm/node_modules/.pnpm/@react-native-community+cli-plugin-metro@7.0.3/node_modules/metro

@@ -0,0 +1 @@
+../../metro@0.67.0/node_modules/metro

packages/metro-resolver-symlinks/test/__fixtures__/pnpm/node_modules/.pnpm/metro@0.67.0/node_modules/metro/index.js

@@ -0,0 +1 @@
+exports.resolve = () => __dirname;

packages/metro-resolver-symlinks/test/__fixtures__/pnpm/node_modules/.pnpm/metro@0.67.0/node_modules/metro/package.json

@@ -0,0 +1,5 @@
+{
+  "name": "metro",
+  "version": "0.67.0",
+  "main": "index.js"
+}

packages/metro-resolver-symlinks/test/resolver.test.ts

@@ -1,5 +1,5 @@
-import * as os from "os";
-import * as path from "path";
+import * as os from "node:os";
+import * as path from "node:path";
 import { requireModuleFromMetro } from "../src/helper";
 import { remapReactNativeModule, resolveModulePath } from "../src/resolver";
 import { useFixture } from "./fixtures";
@@ -12,17 +12,17 @@ const AVAILABLE_PLATFORMS = {
 
 const nixOnlyTest = os.platform() === "win32" ? test.skip : test;
 
-function getMetroResolver(fromDir: string) {
-  return requireModuleFromMetro<typeof import("metro-resolver")>(
-    "metro-resolver",
-    fromDir
-  ).resolve;
-}
-
-describe("getMetroResolver", () => {
+describe("requireModuleFromMetro", () => {
   // eslint-disable-next-line @typescript-eslint/no-explicit-any
   const context: any = {};
 
+  function getMetroResolver(fromDir: string) {
+    return requireModuleFromMetro<typeof import("metro-resolver")>(
+      "metro-resolver",
+      fromDir
+    ).resolve;
+  }
+
   test("returns `metro-resolver` installed by `react-native`", () => {
     const p = useFixture("metro-resolver-duplicates");
     expect(getMetroResolver(p)(context, "", null)).toEqual(

packages/tools-react-native/src/metro.ts

@@ -3,7 +3,7 @@ import {
   readPackage,
 } from "@rnx-kit/tools-node/package";
 
-function resolveDependency(name: string, startDir: string): string | undefined {
+function resolveFrom(name: string, startDir: string): string | undefined {
   return findPackageDependencyDir(name, {
     startDir,
     resolveSymlinks: true,
@@ -16,21 +16,21 @@ function resolveDependency(name: string, startDir: string): string | undefined {
  * @returns The path to the Metro installation; `undefined` if Metro could not be found
  */
 export function findMetroPath(projectRoot = process.cwd()): string | undefined {
-  const rnPath = resolveDependency("react-native", projectRoot);
+  const rnPath = resolveFrom("react-native", projectRoot);
   if (!rnPath) {
     return undefined;
   }
 
-  const cliPath = resolveDependency("@react-native-community/cli", rnPath);
+  const cliPath = resolveFrom("@react-native-community/cli", rnPath);
   if (!cliPath) {
     return undefined;
   }
 
-  const cliMetroPath = resolveDependency(
+  const cliMetroPath = resolveFrom(
     "@react-native-community/cli-plugin-metro",
     cliPath
   );
-  return resolveDependency("metro", cliMetroPath || cliPath);
+  return resolveFrom("metro", cliMetroPath || cliPath);
 }
 
 /**