Propagates the extensions overrides provided by CLI during files walk (#8668)

* Propagates the extensions overrides provided by CLI during files walk

* Adds tests for issue #7620, PR #8668

packages/babel-cli/src/babel/file.js

@@ -137,7 +137,11 @@ export default async function({ cliOptions, babelOptions }) {
         const dirname = filename;
 
         util
-          .readdirForCompilable(filename, cliOptions.includeDotfiles)
+          .readdirForCompilable(
+            filename,
+            cliOptions.includeDotfiles,
+            cliOptions.extensions,
+          )
           .forEach(function(filename) {
             _filenames.push(path.join(dirname, filename));
           });

packages/babel-cli/src/babel/util.js

@@ -29,8 +29,11 @@ export function readdir(
 export function readdirForCompilable(
   dirname: string,
   includeDotfiles: boolean,
+  altExts?: Array<string>,
 ) {
-  return readdir(dirname, includeDotfiles, isCompilableExtension);
+  return readdir(dirname, includeDotfiles, function(filename) {
+    return isCompilableExtension(filename, altExts);
+  });
 }
 
 /**

packages/babel-cli/test/fixtures/babel/dir --out-file --extensions/in-files/src/bar/bar.es

@@ -0,0 +1 @@
+ (() => 42)

packages/babel-cli/test/fixtures/babel/dir --out-file --extensions/in-files/src/foo.es

@@ -0,0 +1 @@
+arr.map(x => x * MULTIPLIER);

packages/babel-cli/test/fixtures/babel/dir --out-file --extensions/options.json

@@ -0,0 +1,3 @@
+{
+  "args": ["src", "--out-file", "test.js", "--extensions", ".es"]
+}

packages/babel-cli/test/fixtures/babel/dir --out-file --extensions/out-files/test.js

@@ -0,0 +1,10 @@
+"use strict";
+
+(function () {
+  return 42;
+});
+"use strict";
+
+arr.map(function (x) {
+  return x * MULTIPLIER;
+});