diff --git a/tests/projectTypeDetector.test.ts b/tests/projectTypeDetector.test.ts
new file mode 100644
index 0000000..8f05181
--- /dev/null
+++ b/tests/projectTypeDetector.test.ts
@@ -0,0 +1,205 @@
+import * as fs from 'fs';
+import * as path from 'path';
+import { ProjectTypeDetector } from '../src/analyzers/projectTypeDetector';
+
+describe('ProjectTypeDetector', () => {
+  let detector: ProjectTypeDetector;
+  let testDir: string;
+
+  beforeEach(async () => {
+    detector = new ProjectTypeDetector();
+    testDir = path.join(__dirname, 'test-projects', `test-${Date.now()}`);
+    await fs.promises.mkdir(testDir, { recursive: true });
+  });
+
+  afterEach(async () => {
+    if (await fs.promises.stat(testDir).catch(() => null)) {
+      await fs.promises.rm(testDir, { recursive: true });
+    }
+  });
+
+  describe('detect', () => {
+    it('should detect TypeScript project with tsconfig.json', async () => {
+      const tsconfig = { compilerOptions: { target: 'ES2020' } };
+      await fs.promises.writeFile(
+        path.join(testDir, 'tsconfig.json'),
+        JSON.stringify(tsconfig)
+      );
+      await fs.promises.writeFile(
+        path.join(testDir, 'index.ts'),
+        'const x: string = "hello";'
+      );
+
+      const result = await detector.detect(testDir);
+
+      expect(result.languages).toContain('TypeScript');
+      expect(result.primaryLanguage).toBe('TypeScript');
+    });
+
+    it('should detect JavaScript project with package.json', async () => {
+      const packageJson = { dependencies: { express: '^4.0.0' } };
+      await fs.promises.writeFile(
+        path.join(testDir, 'package.json'),
+        JSON.stringify(packageJson)
+      );
+      await fs.promises.writeFile(
+        path.join(testDir, 'index.js'),
+        'const express = require("express");'
+      );
+
+      const result = await detector.detect(testDir);
+
+      expect(result.languages).toContain('JavaScript');
+      expect(result.primaryLanguage).toBe('JavaScript');
+    });
+
+    it('should detect Python project with requirements.txt', async () => {
+      await fs.promises.writeFile(
+        path.join(testDir, 'requirements.txt'),
+        'django>=3.0.0\nflask>=1.0.0'
+      );
+      await fs.promises.writeFile(
+        path.join(testDir, 'main.py'),
+        'import django\nfrom flask import Flask'
+      );
+
+      const result = await detector.detect(testDir);
+
+      expect(result.languages).toContain('Python');
+    });
+
+    it('should detect Go project with go.mod', async () => {
+      await fs.promises.writeFile(
+        path.join(testDir, 'go.mod'),
+        'module example.com/mymodule\n\ngo 1.21\n\nrequire github.com/gin-gonic/gin v1.9.0'
+      );
+      await fs.promises.writeFile(
+        path.join(testDir, 'main.go'),
+        'package main\nimport "fmt"'
+      );
+
+      const result = await detector.detect(testDir);
+
+      expect(result.languages).toContain('Go');
+      expect(result.frameworks).toContain('Gin');
+    });
+
+    it('should detect Rust project with Cargo.toml', async () => {
+      await fs.promises.writeFile(
+        path.join(testDir, 'Cargo.toml'),
+        '[package]\nname = "myproject"\nversion = "0.1.0"\n\n[dependencies]\nserde = { version = "1.0", features = ["derive"] }'
+      );
+      await fs.promises.writeFile(
+        path.join(testDir, 'main.rs'),
+        'fn main() { println!("Hello"); }'
+      );
+
+      const result = await detector.detect(testDir);
+
+      expect(result.languages).toContain('Rust');
+      expect(result.buildTools).toContain('cargo');
+    });
+
+    it('should detect React framework from package.json', async () => {
+      const packageJson = {
+        dependencies: { react: '^18.0.0', 'react-dom': '^18.0.0' },
+        devDependencies: { '@types/react': '^18.0.0' }
+      };
+      await fs.promises.writeFile(
+        path.join(testDir, 'package.json'),
+        JSON.stringify(packageJson)
+      );
+      await fs.promises.writeFile(
+        path.join(testDir, 'App.tsx'),
+        'import React from "react";'
+      );
+
+      const result = await detector.detect(testDir);
+
+      expect(result.languages).toContain('TypeScript');
+      expect(result.frameworks).toContain('React');
+    });
+
+    it('should detect Next.js framework', async () => {
+      const packageJson = {
+        dependencies: {
+          next: '^14.0.0',
+          react: '^18.0.0',
+          'react-dom': '^18.0.0'
+        }
+      };
+      await fs.promises.writeFile(
+        path.join(testDir, 'package.json'),
+        JSON.stringify(packageJson)
+      );
+      await fs.promises.writeFile(
+        path.join(testDir, 'next.config.js'),
+        'module.exports = {}'
+      );
+      await fs.promises.mkdir(path.join(testDir, 'pages'), { recursive: true });
+      await fs.promises.writeFile(
+        path.join(testDir, 'pages', 'index.tsx'),
+        'export default function() { return null; }'
+      );
+
+      const result = await detector.detect(testDir);
+
+      expect(result.frameworks).toContain('Next.js');
+    });
+
+    it('should detect Django framework', async () => {
+      await fs.promises.writeFile(
+        path.join(testDir, 'requirements.txt'),
+        'django>=4.0.0\ndjangorestframework>=3.0.0'
+      );
+
+      const result = await detector.detect(testDir);
+
+      expect(result.frameworks).toContain('Django');
+    });
+
+    it('should detect FastAPI framework', async () => {
+      await fs.promises.writeFile(
+        path.join(testDir, 'requirements.txt'),
+        'fastapi>=0.100.0\nuvicorn>=0.23.0'
+      );
+
+      const result = await detector.detect(testDir);
+
+      expect(result.frameworks).toContain('FastAPI');
+    });
+
+    it('should detect build tools from config files', async () => {
+      await fs.promises.writeFile(
+        path.join(testDir, 'package.json'),
+        JSON.stringify({ dependencies: {} })
+      );
+      await fs.promises.writeFile(path.join(testDir, 'Makefile'), 'all:\n\techo "build"');
+
+      const result = await detector.detect(testDir);
+
+      expect(result.buildTools).toContain('npm');
+      expect(result.buildTools).toContain('make');
+    });
+
+    it('should detect multiple languages in same project', async () => {
+      await fs.promises.writeFile(
+        path.join(testDir, 'package.json'),
+        JSON.stringify({ dependencies: {} })
+      );
+      await fs.promises.writeFile(path.join(testDir, 'index.js'), 'console.log("js");');
+      await fs.promises.writeFile(path.join(testDir, 'main.py'), 'print("python")');
+
+      const result = await detector.detect(testDir);
+
+      expect(result.languages.length).toBeGreaterThan(1);
+    });
+
+    it('should return Unknown for empty directory', async () => {
+      const result = await detector.detect(testDir);
+
+      expect(result.primaryLanguage).toBe('Unknown');
+      expect(result.languages).toHaveLength(0);
+    });
+  });
+});