Convert Jest configuration to TypeScript (#561)

jest.config.js

@@ -1,8 +0,0 @@
-module.exports = {
-  ...require("@snowpack/app-scripts-react/jest.config.js")(),
-  "snapshotSerializers": ["enzyme-to-json/serializer"],
-  "moduleNameMapper": {
-    "\\.(jpg|jpeg|png|gif|eot|otf|webp|svg|ttf|woff|woff2|mp4|webm|wav|mp3|m4a|aac|oga)$": "<rootDir>/src/__mocks__/fileMock.js",
-    "\\.(css|less)$": "<rootDir>/src/__mocks__/styleMock.js"
-  }
-};

jest.config.ts

@@ -0,0 +1,16 @@
+// See: https://github.com/snowpackjs/snowpack/issues/3242
+// @ts-ignore
+import snowpackConfig from "@snowpack/app-scripts-react/jest.config.js";
+import { Config } from "@jest/types";
+
+const config: Config.InitialOptions = {
+  ...snowpackConfig(),
+  setupFilesAfterEnv: ["<rootDir>/jest.setup.ts"],
+  snapshotSerializers: ["enzyme-to-json/serializer"],
+  moduleNameMapper: {
+    "\\.(jpg|jpeg|png|gif|eot|otf|webp|svg|ttf|woff|woff2|mp4|webm|wav|mp3|m4a|aac|oga)$": "<rootDir>/src/__mocks__/fileMock.js",
+    "\\.(css|less)$": "<rootDir>/src/__mocks__/styleMock.js"
+  }
+};
+
+export default config;

jest.setup.ts

@@ -26,4 +26,5 @@ import Adapter from 'enzyme-adapter-react-16';
 configure({ adapter: new Adapter() });
 
 // eslint-disable-next-line no-undef
+// @ts-ignore
 global.MutationObserver = window.MutationObserver;

package.json

@@ -41,6 +41,7 @@
   "devDependencies": {
     "@babel/core": "^7.10.5",
     "@babel/preset-typescript": "^7.10.4",
+    "@jest/types": "^26.6.2",
     "@snowpack/app-scripts-react": "^1.10.0",
     "@snowpack/plugin-postcss": "1.0.4",
     "@snowpack/plugin-webpack": "2.0.12",
@@ -57,6 +58,7 @@
     "@testing-library/react": "^10.4.6",
     "@types/dot": "^1.1.4",
     "@types/enzyme": "^3.10.5",
+    "@types/enzyme-adapter-react-16": "^1.0.6",
     "@types/file-saver": "^2.0.1",
     "@types/jest": "^26.0.4",
     "@types/lodash": "^4.14.165",
@@ -77,7 +79,7 @@
     "eslint-plugin-react": "^7.20.5",
     "grunt": "^1.2.1",
     "grunt-contrib-copy": "^1.0.0",
-    "jest": "^25.4.0",
+    "jest": "^26.6.3",
     "mutationobserver-shim": "^0.3.7",
     "postcss": "^7.0.32",
     "postcss-cli": "^7.1.1",
@@ -86,6 +88,7 @@
     "react-is": "^16.13.1",
     "react-scripts": "^3.4.1",
     "snowpack": "2.11.1",
+    "ts-node": "^9.1.1",
     "typescript": "^3.8.3"
   }
 }