Replace period in CSS Module classnames

packages/react-dev-utils/__tests__/getCSSModuleLocalIdent.test.js

@@ -0,0 +1,51 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+'use strict';
+
+const getCSSModuleLocalIdent = require('../getCSSModuleLocalIdent');
+
+const rootContext = '/path';
+const defaultClassName = 'class';
+const options = { context: undefined, hashPrefix: '', regExp: null };
+
+const tests = [
+  {
+    resourcePath: '/path/to/file.module.css',
+    expected: 'file_class__13tFD',
+  },
+  {
+    resourcePath: '/path/to/file.module.scss',
+    expected: 'file_class__3lYUI',
+  },
+  {
+    resourcePath: '/path/to/file.module.sass',
+    expected: 'file_class__2KnOB',
+  },
+  {
+    resourcePath: '/path/to/file.name.module.css',
+    expected: 'file_name_class__1OzEh',
+  },
+];
+
+describe('getCSSModuleLocalIdent', () => {
+  tests.forEach(test => {
+    const { className = defaultClassName, expected, resourcePath } = test;
+    it(JSON.stringify({ resourcePath, className }), () => {
+      const ident = getCSSModuleLocalIdent(
+        {
+          resourcePath,
+          rootContext,
+        },
+        '[hash:base64]',
+        className,
+        options
+      );
+      expect(ident).toBe(expected);
+    });
+  });
+});

packages/react-dev-utils/getCSSModuleLocalIdent.js

@@ -35,6 +35,6 @@ module.exports = function getLocalIdent(
     fileNameOrFolder + '_' + localName + '__' + hash,
     options
   );
-  // remove the .module that appears in every classname when based on the file.
-  return className.replace('.module_', '_');
+  // Remove the .module that appears in every classname when based on the file and replace all "." with "_".
+  return className.replace('.module_', '_').replace(/\./g, '_');
 };