Visual Console Client: added mocks to the test runner

Former-commit-id: 239ef3cff19026884bac8f70a101d8d8dc95d34d

visual_console/__mocks__/fileMock.js

@@ -0,0 +1 @@
+module.exports = "test-file-stub";

visual_console/__mocks__/styleMock.js

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

visual_console/jest.config.js

@@ -4,5 +4,12 @@ module.exports = {
     "^.+\\.tsx?$": "ts-jest"
   },
   testRegex: "(/__tests__/.*|(\\.|/)(test|spec))\\.tsx?$",
-  moduleFileExtensions: ["ts", "tsx", "js", "jsx", "json", "node"]
+  moduleFileExtensions: ["ts", "tsx", "js", "jsx", "json", "node"],
+  // This configuration is used to mock the css and file imports used by Webpack.
+  // https://jestjs.io/docs/en/webpack.html
+  moduleNameMapper: {
+    "\\.(jpg|jpeg|png|gif|eot|otf|webp|svg|ttf|woff|woff2|mp4|webm|wav|mp3|m4a|aac|oga)$":
+      "<rootDir>/__mocks__/fileMock.js",
+    "\\.(css|less)$": "<rootDir>/__mocks__/styleMock.js"
+  }
 };