Add support for .cjs config files (#10599)

* Remove duplicate config loading logic and errors

* Add support for .cjs config files

* Add tests

* [tests] Fallback for fs.promises on node 6

packages/babel-core/src/config/files/configuration.js

@@ -18,26 +18,22 @@ import type { CallerMetadata } from "../validation/options";
 
 const debug = buildDebug("babel:config:loading:files:configuration");
 
-const BABEL_CONFIG_JS_FILENAME = "babel.config.js";
-const BABEL_CONFIG_JSON_FILENAME = "babel.config.json";
 const ROOT_CONFIG_FILENAMES = [
-  BABEL_CONFIG_JS_FILENAME,
+  "babel.config.js",
-  BABEL_CONFIG_JSON_FILENAME,
+  "babel.config.cjs",
+  "babel.config.json",
 ];
+const RELATIVE_CONFIG_FILENAMES = [".babelrc", ".babelrc.js", ".babelrc.cjs"];
 
-const BABELRC_FILENAME = ".babelrc";
-const BABELRC_JS_FILENAME = ".babelrc.js";
 const BABELIGNORE_FILENAME = ".babelignore";
 
 export function findConfigUpwards(rootDir: string): string | null {
   let dirname = rootDir;
   while (true) {
-    if (
+    const configFileFound = ROOT_CONFIG_FILENAMES.some(filename =>
-      fs.existsSync(path.join(dirname, BABEL_CONFIG_JS_FILENAME)) ||
+      fs.existsSync(path.join(dirname, filename)),
-      fs.existsSync(path.join(dirname, BABEL_CONFIG_JSON_FILENAME))
+    );
-    ) {
+    if (configFileFound) return dirname;
-      return dirname;
-    }
 
     const nextDir = path.dirname(dirname);
     if (dirname === nextDir) break;
@@ -59,45 +55,15 @@ export function findRelativeConfig(
 
   for (const loc of packageData.directories) {
     if (!config) {
-      config = [BABELRC_FILENAME, BABELRC_JS_FILENAME].reduce(
+      config = loadOneConfig(
-        (previousConfig: ConfigFile | null, name) => {
+        RELATIVE_CONFIG_FILENAMES,
-          const filepath = path.join(loc, name);
+        loc,
-          const config = readConfig(filepath, envName, caller);
+        envName,
-
+        caller,
-          if (config && previousConfig) {
-            throw new Error(
-              `Multiple configuration files found. Please remove one:\n` +
-                ` - ${path.basename(previousConfig.filepath)}\n` +
-                ` - ${name}\n` +
-                `from ${loc}`,
-            );
-          }
-
-          return config || previousConfig;
-        },
-        null,
-      );
-
-      const pkgConfig =
         packageData.pkg && packageData.pkg.dirname === loc
           ? packageToBabelConfig(packageData.pkg)
-          : null;
+          : null,
-
+      );
-      if (pkgConfig) {
-        if (config) {
-          throw new Error(
-            `Multiple configuration files found. Please remove one:\n` +
-              ` - ${path.basename(pkgConfig.filepath)}#babel\n` +
-              ` - ${path.basename(config.filepath)}\n` +
-              `from ${loc}`,
-          );
-        }
-        config = pkgConfig;
-      }
-
-      if (config) {
-        debug("Found configuration %o from %o.", config.filepath, dirname);
-      }
     }
 
     if (!ignore) {
@@ -118,24 +84,31 @@ export function findRootConfig(
   envName: string,
   caller: CallerMetadata | void,
 ): ConfigFile | null {
-  const config = ROOT_CONFIG_FILENAMES.reduce(
+  return loadOneConfig(ROOT_CONFIG_FILENAMES, dirname, envName, caller);
-    (previousConfig: ConfigFile | null, name) => {
+}
-      const filepath = path.resolve(dirname, name);
-      const config = readConfig(filepath, envName, caller);
 
-      if (config && previousConfig) {
+function loadOneConfig(
-        throw new Error(
+  names: string[],
-          `Multiple configuration files found. Please remove one:\n` +
+  dirname: string,
-            ` - ${path.basename(previousConfig.filepath)}\n` +
+  envName: string,
-            ` - ${name}\n` +
+  caller: CallerMetadata | void,
-            `from ${dirname}`,
+  previousConfig?: ConfigFile | null = null,
-        );
+): ConfigFile | null {
-      }
+  const config = names.reduce((previousConfig: ConfigFile | null, name) => {
+    const filepath = path.resolve(dirname, name);
+    const config = readConfig(filepath, envName, caller);
 
-      return config || previousConfig;
+    if (config && previousConfig) {
-    },
+      throw new Error(
-    null,
+        `Multiple configuration files found. Please remove one:\n` +
-  );
+          ` - ${path.basename(previousConfig.filepath)}\n` +
+          ` - ${name}\n` +
+          `from ${dirname}`,
+      );
+    }
+
+    return config || previousConfig;
+  }, previousConfig);
 
   if (config) {
     debug("Found configuration %o from %o.", config.filepath, dirname);
@@ -165,7 +138,8 @@ export function loadConfig(
  * throw if there are parsing errors while loading a config.
  */
 function readConfig(filepath, envName, caller): ConfigFile | null {
-  return path.extname(filepath) === ".js"
+  const ext = path.extname(filepath);
+  return ext === ".js" || ext === ".cjs"
     ? readConfigJS(filepath, { envName, caller })
     : readConfigJSON5(filepath);
 }

packages/babel-core/test/config-chain.js

@@ -1,8 +1,44 @@
 import fs from "fs";
+import os from "os";
 import path from "path";
 import escapeRegExp from "lodash/escapeRegExp";
 import { loadOptions as loadOptionsOrig } from "../lib";
 
+// TODO: In Babel 8, we can directly uses fs.promises which is supported by
+// node 8+
+const pfs =
+  fs.promises ??
+  new Proxy(fs, {
+    get(target, name) {
+      if (name === "copyFile") {
+        // fs.copyFile is only supported since node 8.5
+        // https://stackoverflow.com/a/30405105/2359289
+        return function copyFile(source, target) {
+          const rd = fs.createReadStream(source);
+          const wr = fs.createWriteStream(target);
+          return new Promise(function(resolve, reject) {
+            rd.on("error", reject);
+            wr.on("error", reject);
+            wr.on("finish", resolve);
+            rd.pipe(wr);
+          }).catch(function(error) {
+            rd.destroy();
+            wr.end();
+            throw error;
+          });
+        };
+      }
+
+      return (...args) =>
+        new Promise((resolve, reject) =>
+          target[name](...args, (error, result) => {
+            if (error) reject(error);
+            else resolve(result);
+          }),
+        );
+    },
+  });
+
 function fixture(...args) {
   return path.join(__dirname, "fixtures", "config", ...args);
 }
@@ -14,6 +50,24 @@ function loadOptions(opts) {
   });
 }
 
+function pairs(items) {
+  const pairs = [];
+  for (let i = 0; i < items.length - 1; i++) {
+    for (let j = i + 1; j < items.length; j++) {
+      pairs.push([items[i], items[j]]);
+    }
+  }
+  return pairs;
+}
+
+async function getTemp(name) {
+  const cwd = await pfs.mkdtemp(os.tmpdir() + path.sep + name);
+  const tmp = name => path.join(cwd, name);
+  const config = name =>
+    pfs.copyFile(fixture("config-files-templates", name), tmp(name));
+  return { cwd, tmp, config };
+}
+
 describe("buildConfigChain", function() {
   describe("test", () => {
     describe("single", () => {
@@ -944,159 +998,122 @@ describe("buildConfigChain", function() {
       }
     });
 
-    it("should load babel.config.json", () => {
+    describe("root", () => {
-      const filename = fixture("config-files", "babel-config-json", "src.js");
+      test.each(["babel.config.json", "babel.config.js", "babel.config.cjs"])(
+        "should load %s",
+        async name => {
+          const { cwd, tmp, config } = await getTemp(
+            `babel-test-load-config-${name}`,
+          );
+          const filename = tmp("src.js");
 
-      expect(
+          await config(name);
-        loadOptions({
-          filename,
-          cwd: path.dirname(filename),
-        }),
-      ).toEqual({
-        ...getDefaults(),
-        filename: filename,
-        cwd: path.dirname(filename),
-        root: path.dirname(filename),
-        comments: true,
-      });
-    });
 
-    it("should load babel.config.js", () => {
+          expect(
-      const filename = fixture("config-files", "babel-config-js", "src.js");
+            loadOptions({
-
+              filename,
-      expect(
+              cwd,
-        loadOptions({
+            }),
-          filename,
+          ).toEqual({
-          cwd: path.dirname(filename),
+            ...getDefaults(),
-        }),
+            filename,
-      ).toEqual({
+            cwd,
-        ...getDefaults(),
+            root: cwd,
-        filename: filename,
+            comments: true,
-        cwd: path.dirname(filename),
+          });
-        root: path.dirname(filename),
+        },
-        comments: true,
-      });
-    });
-
-    it("should whtow if both babel.config.json and babel.config.js are used", () => {
-      const filename = fixture(
-        "config-files",
-        "babel-config-js-and-json",
-        "src.js",
       );
 
-      expect(() =>
+      test.each(
-        loadOptions({ filename, cwd: path.dirname(filename) }),
+        pairs(["babel.config.json", "babel.config.js", "babel.config.cjs"]),
-      ).toThrow(/Multiple configuration files found/);
+      )("should throw if both %s and %s are used", async (name1, name2) => {
+        const { cwd, tmp, config } = await getTemp(
+          `babel-test-dup-config-${name1}-${name2}`,
+        );
+
+        await Promise.all([config(name1), config(name2)]);
+
+        expect(() => loadOptions({ filename: tmp("src.js"), cwd })).toThrow(
+          /Multiple configuration files found/,
+        );
+      });
     });
 
-    it("should load .babelrc", () => {
+    describe("relative", () => {
-      const filename = fixture("config-files", "babelrc", "src.js");
+      test.each(["package.json", ".babelrc", ".babelrc.js", ".babelrc.cjs"])(
+        "should load %s",
+        async name => {
+          const { cwd, tmp, config } = await getTemp(
+            `babel-test-load-config-${name}`,
+          );
+          const filename = tmp("src.js");
 
-      expect(
+          await config(name);
-        loadOptions({
+
-          filename,
+          expect(
+            loadOptions({
+              filename,
+              cwd,
+            }),
+          ).toEqual({
+            ...getDefaults(),
+            filename,
+            cwd,
+            root: cwd,
+            comments: true,
+          });
+        },
+      );
+
+      it("should load .babelignore", () => {
+        const filename = fixture("config-files", "babelignore", "src.js");
+
+        expect(
+          loadOptions({ filename, cwd: path.dirname(filename) }),
+        ).toBeNull();
+      });
+
+      test.each(
+        pairs(["package.json", ".babelrc", ".babelrc.js", ".babelrc.cjs"]),
+      )("should throw if both %s and %s are used", async (name1, name2) => {
+        const { cwd, tmp, config } = await getTemp(
+          `babel-test-dup-config-${name1}-${name2}`,
+        );
+
+        await Promise.all([config(name1), config(name2)]);
+
+        expect(() => loadOptions({ filename: tmp("src.js"), cwd })).toThrow(
+          /Multiple configuration files found/,
+        );
+      });
+
+      it("should ignore package.json without a 'babel' property", () => {
+        const filename = fixture("config-files", "pkg-ignored", "src.js");
+
+        expect(loadOptions({ filename, cwd: path.dirname(filename) })).toEqual({
+          ...getDefaults(),
+          filename: filename,
           cwd: path.dirname(filename),
-        }),
+          root: path.dirname(filename),
-      ).toEqual({
+          comments: true,
-        ...getDefaults(),
+        });
-        filename: filename,
-        cwd: path.dirname(filename),
-        root: path.dirname(filename),
-        comments: true,
       });
-    });
 
-    it("should load .babelrc.js", () => {
+      test.each`
-      const filename = fixture("config-files", "babelrc-js", "src.js");
+        config            | dir                    | error
+        ${".babelrc"}     | ${"babelrc-error"}     | ${/Error while parsing config - /}
+        ${".babelrc.js"}  | ${"babelrc-js-error"}  | ${/Babelrc threw an error/}
+        ${".babelrc.cjs"} | ${"babelrc-cjs-error"} | ${/Babelrc threw an error/}
+        ${"package.json"} | ${"pkg-error"}         | ${/Error while parsing JSON - /}
+      `("should show helpful errors for $config", ({ dir, error }) => {
+        const filename = fixture("config-files", dir, "src.js");
 
-      expect(loadOptions({ filename, cwd: path.dirname(filename) })).toEqual({
+        expect(() =>
-        ...getDefaults(),
+          loadOptions({ filename, cwd: path.dirname(filename) }),
-        filename: filename,
+        ).toThrow(error);
-        cwd: path.dirname(filename),
-        root: path.dirname(filename),
-        comments: true,
       });
     });
 
-    it("should load package.json#babel", () => {
-      const filename = fixture("config-files", "pkg", "src.js");
-
-      expect(loadOptions({ filename, cwd: path.dirname(filename) })).toEqual({
-        ...getDefaults(),
-        filename: filename,
-        cwd: path.dirname(filename),
-        root: path.dirname(filename),
-        comments: true,
-      });
-    });
-
-    it("should load .babelignore", () => {
-      const filename = fixture("config-files", "babelignore", "src.js");
-
-      expect(loadOptions({ filename, cwd: path.dirname(filename) })).toBeNull();
-    });
-
-    it("should throw if there are both .babelrc and .babelrc.js", () => {
-      const filename = fixture("config-files", "both-babelrc", "src.js");
-
-      expect(() =>
-        loadOptions({ filename, cwd: path.dirname(filename) }),
-      ).toThrow(/Multiple configuration files found/);
-    });
-
-    it("should throw if there are both .babelrc and package.json", () => {
-      const filename = fixture("config-files", "pkg-babelrc", "src.js");
-
-      expect(() =>
-        loadOptions({ filename, cwd: path.dirname(filename) }),
-      ).toThrow(/Multiple configuration files found/);
-    });
-
-    it("should throw if there are both .babelrc.js and package.json", () => {
-      const filename = fixture("config-files", "pkg-babelrc-js", "src.js");
-
-      expect(() =>
-        loadOptions({ filename, cwd: path.dirname(filename) }),
-      ).toThrow(/Multiple configuration files found/);
-    });
-
-    it("should ignore package.json without a 'babel' property", () => {
-      const filename = fixture("config-files", "pkg-ignored", "src.js");
-
-      expect(loadOptions({ filename, cwd: path.dirname(filename) })).toEqual({
-        ...getDefaults(),
-        filename: filename,
-        cwd: path.dirname(filename),
-        root: path.dirname(filename),
-        comments: true,
-      });
-    });
-
-    it("should show helpful errors for .babelrc", () => {
-      const filename = fixture("config-files", "babelrc-error", "src.js");
-
-      expect(() =>
-        loadOptions({ filename, cwd: path.dirname(filename) }),
-      ).toThrow(/Error while parsing config - /);
-    });
-
-    it("should show helpful errors for .babelrc.js", () => {
-      const filename = fixture("config-files", "babelrc-js-error", "src.js");
-
-      expect(() =>
-        loadOptions({ filename, cwd: path.dirname(filename) }),
-      ).toThrow(/Babelrc threw an error/);
-    });
-
-    it("should show helpful errors for package.json", () => {
-      const filename = fixture("config-files", "pkg-error", "src.js");
-
-      expect(() =>
-        loadOptions({ filename, cwd: path.dirname(filename) }),
-      ).toThrow(/Error while parsing JSON - /);
-    });
-
     it("should throw when `test` presents but `filename` is not passed", () => {
       expect(() => loadOptions({ test: /\.ts$/, plugins: [] })).toThrow(
         /Configuration contains string\/RegExp pattern/,

packages/babel-core/test/fixtures/config/config-files-templates/.babelrc

@@ -1,3 +1,3 @@
 {
   "comments": true
-}
+}

packages/babel-core/test/fixtures/config/config-files-templates/babel.config.cjs

@@ -1,3 +1,3 @@
 module.exports = {
-  comments: true,
+  comments: true
 };

packages/babel-core/test/fixtures/config/config-files-templates/babel.config.js

@@ -0,0 +1,3 @@
+module.exports = {
+  comments: true
+};

packages/babel-core/test/fixtures/config/config-files/babelrc-cjs-error/.babelrc.cjs

@@ -0,0 +1,3 @@
+module.exports = function() {
+  throw new Error("Babelrc threw an error");
+};

packages/babel-core/test/fixtures/config/config-files/babelrc/.babelrc

@@ -1,3 +0,0 @@
-{
-  comments: true,
-}

packages/babel-core/test/fixtures/config/config-files/both-babelrc/.babelrc

@@ -1 +0,0 @@
-{}

packages/babel-core/test/fixtures/config/config-files/both-babelrc/.babelrc.js

@@ -1 +0,0 @@
-module.exports = {};

packages/babel-core/test/fixtures/config/config-files/pkg-babelrc-js/.babelrc.js

@@ -1 +0,0 @@
-module.exports = {};

packages/babel-core/test/fixtures/config/config-files/pkg-babelrc-js/package.json

@@ -1,3 +0,0 @@
-{
-  "babel": {}
-}

packages/babel-core/test/fixtures/config/config-files/pkg-babelrc/.babelrc

@@ -1 +0,0 @@
-{}

packages/babel-core/test/fixtures/config/config-files/pkg-babelrc/package.json

@@ -1,3 +0,0 @@
-{
-  "babel": {}
-}