solution

src/createServer.js

@@ -1,8 +1,71 @@
 'use strict';
 
+const http = require('http');
+const fs = require('fs');
+
+const HTML =
+  '<form method="post">' +
+  '<input type="text" name="title" />' +
+  '<input type="date" name="date" />' +
+  '<input type="number" name="amount" />' +
+  '<button type="submit" name="amount">submit</button>' +
+  '</form>';
+
 function createServer() {
-  /* Write your code here */
-  // Return instance of http.Server class
+  return http.createServer((req, res) => {
+    const url = new URL(req.url, `http://${req.headers.host}`);
+    const pathname = url.pathname;
+
+    if (pathname !== '/submit-expense' && pathname !== '/') {
+      res.statusCode = 404;
+      res.setHeader('Content-Type', 'text/plain');
+      res.end('404 Not Found');
+
+      return;
+    }
+
+    if (pathname === '/submit-expense' && req.method === 'POST') {
+      const chunks = [];
+
+      req.on('data', (chunk) => {
+        chunks.push(chunk);
+      });
+
+      req.on('end', () => {
+        const body = Buffer.concat(chunks).toString();
+        const data = JSON.parse(body);
+
+        if (!data) {
+          res.statusCode = 404;
+          res.setHeader('Content-Type', 'text/plain');
+          res.end('Invalid Request');
+
+          return;
+        }
+
+        const { date, title, amount } = data;
+
+        if (!date || !title || !amount) {
+          res.statusCode = 400;
+          res.setHeader('Content-Type', 'text/plain');
+          res.end('Bad Request');
+
+          return;
+        }
+
+        fs.writeFile('db/expense.json', body);
+
+        res.statusCode = 200;
+        res.setHeader('Content-Type', 'application/json');
+        res.end(JSON.stringify(data));
+      });
+
+      return;
+    }
+
+    res.setHeader('Content-Type', 'text/html');
+    res.end(HTML);
+  });
 }
 
 module.exports = {

tests/formDataServer.test.js

@@ -10,7 +10,7 @@ const { Server, Agent } = require('http');
 // this prevents `socket hang up` for Node.js 20.10+
 axios.defaults.httpAgent = new Agent({ keepAlive: false });
 
-const PORT = 5701;
+const PORT = 5703;
 const HOST = `http://localhost:${PORT}`;
 
 describe('Form Data Server', () => {
@@ -47,7 +47,7 @@ describe('Form Data Server', () => {
           title: 'Test Expense',
           amount: '100',
         };
-        const response = await axios.post(`${HOST}/add-expense`, expense);
+        const response = await axios.post(`${HOST}/submit-expense`, expense);
 
         expect(response.status).toBe(200);
 
@@ -67,7 +67,7 @@ describe('Form Data Server', () => {
         expect.assertions(2);
 
         try {
-          await axios.post(`${HOST}/add-expense`, expense);
+          await axios.post(`${HOST}/submit-expense`, expense);
         } catch (err) {
           expect(err.response.data.length).toBeGreaterThan(0);
 
@@ -81,9 +81,9 @@ describe('Form Data Server', () => {
           title: 'Test Expense',
           amount: '100',
         };
-        const response = await axios.post(`${HOST}/add-expense`, expense);
+        const response = await axios.post(`${HOST}/submit-expense`, expense);
 
-        expect(response.headers['content-type']).toBe('application/json');
+        expect(response.headers['content-type']).toBe('text/html');
         expect(response.data).toStrictEqual(expense);
       });