Add Jest snapshot test

cloudbuild.yaml

@@ -5,6 +5,9 @@ steps:
 - name: node:lts-alpine
   entrypoint: npm
   args: ['run', 'lint']
+- name: node:lts-alpine
+  entrypoint: npm
+  args: ['run', 'test']
 - name: node:lts-alpine
   entrypoint: npm
   args: ['run', 'build']

eslint.config.mjs

@@ -2,8 +2,11 @@
 
 import eslint from '@eslint/js';
 import tseslint from 'typescript-eslint';
+import eslintJest from 'eslint-plugin-jest';
 
 export default tseslint.config(
   eslint.configs.recommended,
-  ...tseslint.configs.recommended,
-);
+  ...tseslint.configs.strictTypeChecked,
+  ...tseslint.configs.stylisticTypeChecked,
+  { plugins: { jest: eslintJest } }
+);

jest.config.mjs

@@ -0,0 +1,8 @@
+/** @type {import('ts-jest').JestConfigWithTsJest} **/
+export default {
+  testEnvironment: "jsdom",
+  testMatch: ["<rootDir>/test/**/*.ts"],
+  transform: {
+    "^.+.tsx?$": ["ts-jest", {}],
+  },
+};