test(app): configure testing environment and add unit tests across entire app #108 and CI

.github/workflows/ci.yml

@@ -25,7 +25,7 @@ jobs:
         run: npm install
 
       - name: Run tests
-        run: npm test
+        run: npm run test
 
       - name: Build Next.js app
         run: npm run build

jest.config.js

@@ -0,0 +1,15 @@
+const nextJest = require('next/jest');
+
+const createJestConfig = nextJest({
+  dir: './',
+});
+
+const customJestConfig = {
+  setupFilesAfterEnv: ['<rootDir>/jest.setup.js'],
+  testEnvironment: 'jest-environment-jsdom',
+  moduleNameMapper: {
+    '^@/(.*)$': '<rootDir>/src/$1',
+  },
+};
+
+module.exports = createJestConfig(customJestConfig);

jest.setup.js

@@ -0,0 +1 @@
+import '@testing-library/jest-dom';