fix(jest-preset): support ESM config files

.changeset/short-eyes-fix.md

@@ -0,0 +1,5 @@
+---
+"@rnx-kit/tools-react-native": patch
+---
+
+Decouple `getAvailablePlatforms()` from `@react-native-community/cli`

.changeset/strong-cups-sparkle.md

@@ -0,0 +1,5 @@
+---
+"@rnx-kit/jest-preset": patch
+---
+
+Support ESM config files

package.json

@@ -147,11 +147,6 @@
           "tsx"
         ]
       },
-      "packages/eslint-plugin": {
-        "ignoreDependencies": [
-          "eslint-plugin-react-hooks"
-        ]
-      },
       "packages/jest-preset": {
         "ignoreDependencies": [
           "react",

packages/eslint-plugin/package.json

@@ -54,7 +54,6 @@
   },
   "devDependencies": {
     "@rnx-kit/eslint-config": "*",
-    "@rnx-kit/jest-preset": "*",
     "@rnx-kit/scripts": "*",
     "@rnx-kit/tsconfig": "*",
     "@types/eslint": "^9.0.0",
@@ -73,6 +72,6 @@
     "node": ">=16.17"
   },
   "jest": {
-    "preset": "@rnx-kit/jest-preset/private"
+    "preset": "../jest-preset/private/jest-preset.js"
   }
 }

packages/jest-preset/package.json

@@ -28,6 +28,7 @@
     "@babel/core": "^7.0.0",
     "@babel/preset-env": "^7.0.0",
     "@babel/preset-typescript": "^7.0.0",
+    "@rnx-kit/tools-react-native": "^2.0.2",
     "find-up": "^5.0.0"
   },
   "peerDependencies": {

packages/jest-preset/src/index.js

@@ -1,5 +1,5 @@
 const findUp = require("find-up");
-const path = require("path");
+const path = require("node:path");
 
 /**
  * @typedef {import("@jest/types").Config.HasteConfig} HasteConfig
@@ -9,24 +9,6 @@ const path = require("path");
  * @typedef {[string | undefined, string | undefined]} PlatformPath
  */
 
-/**
- * Resolve the path to a dependency given a chain of dependencies leading up to
- * it.
- *
- * Note: This is a copy of the function in `@rnx-kit/tools-node` to avoid
- * circular dependency.
- *
- * @param {string[]} chain Chain of dependencies leading up to the target dependency.
- * @param {string=} startDir Optional starting directory for the search. If not given, the current directory is used.
- * @returns Path to the final dependency's directory.
- */
-function resolveDependencyChain(chain, startDir = process.cwd()) {
-  return chain.reduce((startDir, module) => {
-    const p = require.resolve(`${module}/package.json`, { paths: [startDir] });
-    return path.dirname(p);
-  }, startDir);
-}
-
 /**
  * Returns the current package directory.
  * @returns {string | undefined}
@@ -47,15 +29,26 @@ function getReactNativePlatformPath(rootDir = getPackageDirectory()) {
     throw new Error("Failed to resolve current package root");
   }
 
-  const fs = require("fs");
+  // This should only throw because we haven't built `tools-react-native` yet,
+  // which can happen if we're running repo-wide tools (like Knip).
+  const readReactNativeConfig = (() => {
+    try {
+      const {
+        readReactNativeConfig,
+      } = require("@rnx-kit/tools-react-native/context");
+      return readReactNativeConfig;
+    } catch (_) {
+      return () => undefined;
+    }
+  })();
 
-  const rnConfigPath = path.join(rootDir, "react-native.config.js");
-  if (!fs.existsSync(rnConfigPath)) {
+  const config = readReactNativeConfig(rootDir);
+  if (!config) {
     return [undefined, undefined];
   }
 
-  const { platforms, reactNativePath } = require(rnConfigPath);
-  if (reactNativePath) {
+  const { platforms, reactNativePath } = config;
+  if (reactNativePath && typeof reactNativePath === "string") {
     const resolvedPath = /^\.?\.[/\\]/.test(reactNativePath)
       ? path.resolve(rootDir, reactNativePath)
       : path.dirname(
@@ -68,15 +61,16 @@ function getReactNativePlatformPath(rootDir = getPackageDirectory()) {
     }
   }
 
-  if (platforms) {
-    const names = Object.keys(platforms).filter(
-      (name) => typeof platforms[name].npmPackageName === "string"
+  if (platforms && typeof platforms === "object") {
+    const names = Object.entries(platforms).filter(
+      ([, info]) => typeof info.npmPackageName === "string"
     );
     if (names.length > 1) {
-      console.warn(`Multiple platforms found; picking the first one: ${names}`);
+      const found = names.map(([key]) => key).join(", ");
+      console.warn(`Multiple platforms found; picking the first one: ${found}`);
     }
 
-    return [names[0], rootDir];
+    return [names[0][0], rootDir];
   }
 
   console.warn("No platforms found");
@@ -96,33 +90,20 @@ function getTargetPlatform(defaultPlatform, searchPaths) {
     return getReactNativePlatformPath();
   }
 
-  /** @type {(config?: {projectRoot?: string; selectedPlatform?: string; }) => CLIConfig} */
-  const loadConfig = (() => {
-    const rnCliPath = resolveDependencyChain([
-      "react-native",
-      "@react-native-community/cli",
-    ]);
-    return (
-      require(rnCliPath).loadConfig ||
-      require(`${rnCliPath}/build/tools/config`).default
-    );
-  })();
-
-  // .length on a function returns the number of formal parameters.
-  // fixes https://github.com/react-native-community/cli/pull/2379 changing the number of parameters.
-  const platforms =
-    loadConfig.length == 1 ? loadConfig({}).platforms : loadConfig().platforms;
+  const {
+    getAvailablePlatforms,
+  } = require("@rnx-kit/tools-react-native/platform");
 
-  const targetPlatformConfig = platforms[defaultPlatform];
-  if (!targetPlatformConfig) {
+  const platforms = getAvailablePlatforms(searchPaths.paths[0]);
+  const npmPackageName = platforms[defaultPlatform];
+  if (typeof npmPackageName !== "string") {
     const availablePlatforms = Object.keys(platforms).join(", ");
     throw new Error(
       `'${defaultPlatform}' was not found among available platforms: ${availablePlatforms}`
     );
   }
 
   // `npmPackageName` is unset if target platform is in core.
-  const { npmPackageName } = targetPlatformConfig;
   return [
     defaultPlatform,
     npmPackageName

packages/tools-react-native/context.d.ts

@@ -1,5 +1,6 @@
 export {
   loadContext,
   loadContextAsync,
+  readReactNativeConfig,
   resolveCommunityCLI,
 } from "./lib/context";

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

@@ -1,8 +1,9 @@
 import type { Config } from "@react-native-community/cli-types";
 import { findUp } from "@rnx-kit/tools-node/path";
-import * as crypto from "crypto";
-import * as nodefs from "fs";
-import * as path from "path";
+import * as crypto from "node:crypto";
+import * as nodefs from "node:fs";
+import * as path from "node:path";
+import { REACT_NATIVE_CONFIG_FILES } from "./context";
 
 const HASH_ALGO = "sha256";
 const UTF8 = { encoding: "utf-8" as const };
@@ -45,7 +46,7 @@ function updateHash(
 export function getCurrentState(projectRoot: string): string {
   const sha2 = crypto.createHash(HASH_ALGO);
 
-  const configFiles = ["package.json", "react-native.config.js"];
+  const configFiles = ["package.json", ...REACT_NATIVE_CONFIG_FILES];
   updateHash(sha2, configFiles, projectRoot, "all");
 
   const lockfiles = [

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

@@ -4,6 +4,9 @@ import {
   findPackageDependencyDir,
   readPackage,
 } from "@rnx-kit/tools-node/package";
+import { spawnSync } from "node:child_process";
+import * as fs from "node:fs";
+import * as path from "node:path";
 import {
   getCurrentState,
   getSavedState,
@@ -15,6 +18,13 @@ import {
 // `react-native`. Consumers have to take a direct dependency on CLI instead.
 const RN_CLI_DECOUPLED = 76;
 
+export const REACT_NATIVE_CONFIG_FILES = [
+  "react-native.config.ts",
+  "react-native.config.mjs",
+  "react-native.config.cjs",
+  "react-native.config.js",
+];
+
 function toNumber(version: string): number {
   const [major, minor = 0] = version.split(".");
   return Number(major) * 1000 + Number(minor);
@@ -115,3 +125,35 @@ export async function loadContextAsync(
   saveConfigToCache(projectRoot, state, config);
   return config;
 }
+
+export function readReactNativeConfig(
+  packageDir: string,
+  cwd = process.cwd()
+): Record<string, unknown> | undefined {
+  for (const configFile of REACT_NATIVE_CONFIG_FILES) {
+    const configPath = path.join(packageDir, configFile);
+    if (fs.existsSync(configPath)) {
+      const url =
+        process.platform === "win32"
+          ? `file://${configPath.replaceAll("\\", "/")}`
+          : configPath;
+      const args = [
+        "--no-warnings",
+        "--eval",
+        `import("${url}").then((config) => console.log(JSON.stringify(config.default ?? config)));`,
+      ];
+
+      const { stderr, stdout } = spawnSync(process.argv0, args, { cwd });
+
+      const errors = stderr?.toString().trim();
+      if (errors) {
+        console.error(`${configPath}: ${errors}`);
+      }
+
+      const json = stdout?.toString().trim();
+      return json ? JSON.parse(json) : undefined;
+    }
+  }
+
+  return undefined;
+}

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

@@ -1,4 +1,9 @@
-export { loadContext, loadContextAsync, resolveCommunityCLI } from "./context";
+export {
+  loadContext,
+  loadContextAsync,
+  readReactNativeConfig,
+  resolveCommunityCLI,
+} from "./context";
 export {
   findMetroPath,
   getMetroVersion,