diff --git a/tests/test_detection.py b/tests/test_detection.py
new file mode 100644
index 0000000..ca5e689
--- /dev/null
+++ b/tests/test_detection.py
@@ -0,0 +1,126 @@
+"""Tests for project detection functionality."""
+
+from pathlib import Path
+
+from src.detectors.framework import FrameworkDetector
+from src.detectors.ide import IDEDetector
+from src.detectors.language import LanguageDetector
+
+
+class TestLanguageDetector:
+    """Tests for LanguageDetector class."""
+
+    def test_detect_python_from_requirements(self, python_project: Path):
+        """Test Python detection from requirements.txt."""
+        detector = LanguageDetector()
+        languages = detector.detect(python_project)
+        assert "python" in languages
+
+    def test_detect_python_from_setup_py(self, python_project: Path):
+        """Test Python detection from setup.py."""
+        detector = LanguageDetector()
+        languages = detector.detect(python_project)
+        assert "python" in languages
+
+    def test_detect_nodejs_from_package_json(self, nodejs_project: Path):
+        """Test Node.js detection from package.json."""
+        detector = LanguageDetector()
+        languages = detector.detect(nodejs_project)
+        assert "nodejs" in languages
+
+    def test_detect_no_language_in_empty_dir(self, temp_project_dir: Path):
+        """Test that empty directory has no detected languages."""
+        detector = LanguageDetector()
+        languages = detector.detect(temp_project_dir)
+        assert len(languages) == 0
+
+    def test_get_priority(self):
+        """Test that detector returns correct priority."""
+        detector = LanguageDetector()
+        assert detector.get_priority() == 100
+
+    def test_detect_from_content(self, python_project: Path):
+        """Test detection from file content analysis."""
+        detector = LanguageDetector()
+        language_files = detector.detect_from_content(python_project)
+        assert "python" in language_files
+
+
+class TestFrameworkDetector:
+    """Tests for FrameworkDetector class."""
+
+    def test_detect_django_from_manage_py(self, django_project: Path):
+        """Test Django detection from manage.py."""
+        detector = FrameworkDetector()
+        frameworks = detector.detect(django_project)
+        assert "django" in frameworks
+
+    def test_detect_react_from_package_json(self, react_project: Path):
+        """Test React detection from package.json."""
+        detector = FrameworkDetector()
+        frameworks = detector.detect(react_project)
+        assert "react" in frameworks
+
+    def test_get_priority(self):
+        """Test that detector returns correct priority."""
+        detector = FrameworkDetector()
+        assert detector.get_priority() == 90
+
+    def test_detect_no_framework_in_empty_dir(self, temp_project_dir: Path):
+        """Test that empty directory has no detected frameworks."""
+        detector = FrameworkDetector()
+        frameworks = detector.detect(temp_project_dir)
+        assert len(frameworks) == 0
+
+
+class TestIDEDetector:
+    """Tests for IDEDetector class."""
+
+    def test_detect_vscode_from_config(self, vscode_project: Path):
+        """Test VSCode detection from .vscode directory."""
+        detector = IDEDetector()
+        ides = detector.detect(vscode_project)
+        assert "vscode" in ides
+
+    def test_detect_jetbrains_from_idea_dir(self, jetbrains_project: Path):
+        """Test JetBrains detection from .idea directory."""
+        detector = IDEDetector()
+        ides = detector.detect(jetbrains_project)
+        assert "jetbrains" in ides
+
+    def test_detect_vscode_specific_method(self, vscode_project: Path):
+        """Test VSCode detection using specific method."""
+        detector = IDEDetector()
+        assert detector.detect_vscode(vscode_project) is True
+
+    def test_detect_jetbrains_specific_method(self, jetbrains_project: Path):
+        """Test JetBrains detection using specific method."""
+        detector = IDEDetector()
+        assert detector.detect_jetbrains(jetbrains_project) is True
+
+    def test_get_priority(self):
+        """Test that detector returns correct priority."""
+        detector = IDEDetector()
+        assert detector.get_priority() == 80
+
+    def test_detect_no_ide_in_empty_dir(self, temp_project_dir: Path):
+        """Test that empty directory has no detected IDEs."""
+        detector = IDEDetector()
+        ides = detector.detect(temp_project_dir)
+        assert len(ides) == 0
+
+
+class TestMixedProjectDetection:
+    """Tests for detection in mixed projects."""
+
+    def test_detect_multiple_languages(self, mixed_project: Path):
+        """Test detection of multiple languages in mixed project."""
+        detector = LanguageDetector()
+        languages = detector.detect(mixed_project)
+        assert len(languages) >= 1
+
+    def test_detect_django_and_react(self, mixed_project: Path):
+        """Test detection of Django and React in same project."""
+        framework_detector = FrameworkDetector()
+        frameworks = framework_detector.detect(mixed_project)
+        assert len(frameworks) >= 1