add jest

.babelrc

@@ -0,0 +1,3 @@
+{
+  "presets": ["next/babel"]
+}

.eslintrc.json

@@ -1,23 +1,18 @@
 {
-    "env": {
-        "browser": true,
-        "es2020": true,
-        "node": true
+  "env": {
+    "browser": true,
+    "es2020": true,
+    "node": true,
+    "jest": true
+  },
+  "extends": ["eslint:recommended", "plugin:react/recommended"],
+  "parserOptions": {
+    "ecmaFeatures": {
+      "jsx": true
     },
-    "extends": [
-        "eslint:recommended",
-        "plugin:react/recommended"
-    ],
-    "parserOptions": {
-        "ecmaFeatures": {
-            "jsx": true
-        },
-        "ecmaVersion": 11,
-        "sourceType": "module"
-    },
-    "plugins": [
-        "react"
-    ],
-    "rules": {
-    }
+    "ecmaVersion": 11,
+    "sourceType": "module"
+  },
+  "plugins": ["react"],
+  "rules": {}
 }

package.json

@@ -5,7 +5,9 @@
   "scripts": {
     "dev": "next dev",
     "build": "next build",
-    "start": "next start"
+    "start": "next start",
+    "test:watch": "jest --watch",
+    "test:ci": "jest"
   },
   "dependencies": {
     "bootstrap": "^4.5.0",
@@ -21,7 +23,9 @@
     "swr": "^0.2.3"
   },
   "devDependencies": {
+    "babel-jest": "^26.2.2",
     "eslint": "^7.5.0",
-    "eslint-plugin-react": "^7.20.5"
+    "eslint-plugin-react": "^7.20.5",
+    "jest": "^26.2.2"
   }
 }