diff --git a/tests/conftest.py b/tests/conftest.py
new file mode 100644
index 0000000..74049a3
--- /dev/null
+++ b/tests/conftest.py
@@ -0,0 +1,279 @@
+"""Pytest configuration and fixtures for codebase-knowledge-graph-cli tests."""
+
+import tempfile
+from collections.abc import Generator
+from pathlib import Path
+
+import pytest
+
+
+@pytest.fixture
+def temp_project_dir() -> Generator[Path, None, None]:
+    """Create a temporary directory for testing."""
+    with tempfile.TemporaryDirectory() as tmp_dir:
+        yield Path(tmp_dir)
+
+
+@pytest.fixture
+def sample_python_code():
+    return '''
+"""Sample module for testing."""
+
+import os
+import json
+from typing import List, Dict
+
+
+class DataProcessor:
+    """A class for processing data."""
+
+    def __init__(self, config: Dict[str, str]):
+        self.config = config
+        self.cache = {}
+
+    def process(self, items: List[str]) -> List[Dict]:
+        """Process a list of items.
+
+        Args:
+            items: List of strings to process
+
+        Returns:
+            List of processed dictionaries
+        """
+        results = []
+        for item in items:
+            if item in self.cache:
+                results.append(self.cache[item])
+            else:
+                processed = self._process_single(item)
+                self.cache[item] = processed
+                results.append(processed)
+        return results
+
+    def _process_single(self, item: str) -> Dict:
+        """Process a single item."""
+        return {"item": item, "length": len(item)}
+
+
+def main():
+    """Main entry point."""
+    processor = DataProcessor({"debug": "true"})
+    result = processor.process(["hello", "world"])
+    print(json.dumps(result))
+
+
+if __name__ == "__main__":
+    main()
+'''
+
+
+@pytest.fixture
+def sample_javascript_code():
+    return '''
+import { useState, useEffect } from 'react';
+import api from './api';
+
+class DataManager {
+  constructor(config) {
+    this.config = config;
+    this.cache = new Map();
+  }
+
+  async fetchData(url) {
+    if (this.cache.has(url)) {
+      return this.cache.get(url);
+    }
+
+    const response = await fetch(url);
+    const data = await response.json();
+    this.cache.set(url, data);
+    return data;
+  }
+
+  clearCache() {
+    this.cache.clear();
+  }
+}
+
+export function useCustomHook(initialValue) {
+  const [value, setValue] = useState(initialValue);
+
+  useEffect(() => {
+    console.log('Value changed:', value);
+  }, [value]);
+
+  return [value, setValue];
+}
+
+export default DataManager;
+'''
+
+
+@pytest.fixture
+def sample_go_code():
+    return '''package main
+
+import (
+    "fmt"
+    "os"
+)
+
+type Config struct {
+    Host string
+    Port int
+}
+
+func (c *Config) Load() error {
+    return nil
+}
+
+func NewProcessor(config Config) *Processor {
+    return &Processor{config: config}
+}
+
+type Processor struct {
+    config Config
+}
+
+func (p *Processor) Process(data string) error {
+    fmt.Println("Processing:", data)
+    return nil
+}
+
+func main() {
+    config := Config{Host: "localhost", Port: 8080}
+    processor := NewProcessor(config)
+    err := processor.Process("test")
+    if err != nil {
+        os.Exit(1)
+    }
+}
+'''
+
+
+@pytest.fixture
+def sample_rust_code():
+    return '''use std::collections::HashMap;
+
+pub struct Config {
+    host: String,
+    port: u16,
+}
+
+impl Config {
+    pub fn new(host: String, port: u16) -> Self {
+        Config { host, port }
+    }
+
+    pub fn load(&self) -> Result<(), std::io::Error> {
+        Ok(())
+    }
+}
+
+pub struct Processor {
+    config: Config,
+    cache: HashMap<String, String>,
+}
+
+impl Processor {
+    pub fn new(config: Config) -> Self {
+        Processor {
+            config,
+            cache: HashMap::new(),
+        }
+    }
+
+    pub fn process(&mut self, input: &str) -> Result<String, std::io::Error> {
+        if let Some(cached) = self.cache.get(input) {
+            return Ok(cached.clone());
+        }
+
+        let result = format!("Processed: {}", input);
+        self.cache.insert(input.to_string(), result.clone());
+        Ok(result)
+    }
+}
+
+fn main() {
+    let config = Config::new("localhost".to_string(), 8080);
+    let mut processor = Processor::new(config);
+
+    match processor.process("test") {
+        Ok(result) => println!("{}", result),
+        Err(e) => eprintln!("Error: {}", e),
+    }
+}
+'''
+
+
+@pytest.fixture
+def python_project(temp_project_dir: Path) -> Path:
+    """Create a mock Python project structure."""
+    src_dir = temp_project_dir / "src"
+    src_dir.mkdir(exist_ok=True)
+
+    (src_dir / "__init__.py").write_text('"""Package init."""')
+    (src_dir / "main.py").write_text('''
+"""Main module."""
+
+def main():
+    print("Hello, World!")
+
+if __name__ == "__main__":
+    main()
+''')
+
+    (src_dir / "utils.py").write_text('''
+"""Utility functions."""
+
+def helper_function():
+    """A helper function."""
+    return "helper"
+
+class HelperClass:
+    """Helper class."""
+    pass
+''')
+
+    return temp_project_dir
+
+
+@pytest.fixture
+def nodejs_project(temp_project_dir: Path) -> Path:
+    """Create a mock Node.js project structure."""
+    (temp_project_dir / "package.json").write_text('''
+{
+  "name": "test-nodejs-project",
+  "version": "1.0.0",
+  "description": "Test Node.js project",
+  "main": "index.js",
+  "scripts": {
+    "start": "node index.js",
+    "test": "jest"
+  },
+  "dependencies": {
+    "express": "^4.18.0",
+    "lodash": "^4.17.21"
+  },
+  "devDependencies": {
+    "jest": "^29.0.0"
+  }
+}
+''')
+
+    (temp_project_dir / "index.js").write_text('''
+const express = require('express');
+const app = express();
+
+app.get('/', (req, res) => {
+  res.send('Hello World!');
+});
+
+app.listen(3000, () => {
+  console.log('Server running on port 3000');
+});
+
+module.exports = app;
+''')
+
+    return temp_project_dir