diff --git a/tests/test_language_detector.py b/tests/test_language_detector.py
index 7fd5212..932c5f0 100644
--- a/tests/test_language_detector.py
+++ b/tests/test_language_detector.py
@@ -5,73 +5,148 @@ from pathlib import Path
 
 sys.path.insert(0, str(Path(__file__).parent.parent / 'src'))
 
-from gdiffer.language_detector import LanguageDetector, detect_language
+from gdiffer.language_detector import detect_language
 
 
 class TestLanguageDetector:
+    """Tests for LanguageDetector class."""
+
     def test_detect_python_extension(self, language_detector):
+        """Test detecting Python files."""
         assert language_detector.detect_from_filename("test.py") == "python"
         assert language_detector.detect_from_filename("script.pyw") == "python"
+        assert language_detector.detect_from_filename("module.pyx") == "python"
 
     def test_detect_javascript_extension(self, language_detector):
+        """Test detecting JavaScript files."""
         assert language_detector.detect_from_filename("app.js") == "javascript"
+        assert language_detector.detect_from_filename("module.mjs") == "javascript"
+        assert language_detector.detect_from_filename("component.cjs") == "javascript"
+        assert language_detector.detect_from_filename("file.jsx") == "javascript"
+
+    def test_detect_typescript_extension(self, language_detector):
+        """Test detecting TypeScript files."""
+        assert language_detector.detect_from_filename("app.ts") == "typescript"
         assert language_detector.detect_from_filename("component.tsx") == "typescript"
+        assert language_detector.detect_from_filename("module.mts") == "typescript"
 
     def test_detect_java_extension(self, language_detector):
+        """Test detecting Java files."""
         assert language_detector.detect_from_filename("Main.java") == "java"
 
     def test_detect_go_extension(self, language_detector):
+        """Test detecting Go files."""
         assert language_detector.detect_from_filename("main.go") == "go"
 
     def test_detect_rust_extension(self, language_detector):
+        """Test detecting Rust files."""
         assert language_detector.detect_from_filename("lib.rs") == "rust"
 
     def test_detect_c_extensions(self, language_detector):
+        """Test detecting C/C++ files."""
         assert language_detector.detect_from_filename("file.c") == "c"
+        assert language_detector.detect_from_filename("header.h") == "c"
         assert language_detector.detect_from_filename("source.cpp") == "cpp"
+        assert language_detector.detect_from_filename("file.cc") == "cpp"
+        assert language_detector.detect_from_filename("header.hpp") == "cpp"
 
     def test_detect_ruby_extension(self, language_detector):
+        """Test detecting Ruby files."""
         assert language_detector.detect_from_filename("script.rb") == "ruby"
+        assert language_detector.detect_from_filename("template.erb") == "ruby"
 
     def test_detect_php_extension(self, language_detector):
+        """Test detecting PHP files."""
         assert language_detector.detect_from_filename("index.php") == "php"
 
     def test_detect_unknown_extension(self, language_detector):
+        """Test detecting unknown file extensions."""
         assert language_detector.detect_from_filename("file.xyz") is None
         assert language_detector.detect_from_filename("README") is None
 
     def test_detect_from_content_python(self, language_detector):
+        """Test detecting Python from content."""
         code = """def hello():
-    return "Hello"
+    return "Hello, World!"
+
+if __name__ == "__main__":
+    hello()
 """
         assert language_detector.detect_from_content(code) == "python"
 
     def test_detect_from_content_javascript(self, language_detector):
+        """Test detecting JavaScript from content."""
         code = """function greet(name) {
-    return "Hello";
-}"""
+    return "Hello, " + name;
+}
+
+const result = greet("World");
+"""
         assert language_detector.detect_from_content(code) == "javascript"
 
+    def test_detect_from_content_rust(self, language_detector):
+        """Test detecting Rust from content."""
+        code = """fn main() {
+    println!("Hello, World!");
+}
+
+fn add(a: i32, b: i32) -> i32 {
+    a + b
+}
+"""
+        assert language_detector.detect_from_content(code) == "rust"
+
+    def test_detect_from_content_go(self, language_detector):
+        """Test detecting Go from content."""
+        code = """package main
+
+import "fmt"
+
+func main() {
+    fmt.Println("Hello")
+}
+"""
+        assert language_detector.detect_from_content(code) == "go"
+
     def test_detect_combined_filename_content(self, language_detector):
+        """Test detection with both filename and content."""
         result = language_detector.detect("test.py", "def hello(): pass")
         assert result == "python"
 
+    def test_detect_script_without_extension(self, language_detector):
+        """Test detecting script without file extension."""
+        result = language_detector.detect("Makefile", "all:\n\techo hello")
+        assert result == "text"
+
     def test_get_supported_languages(self, language_detector):
+        """Test getting list of supported languages."""
         languages = language_detector.get_supported_languages()
+        assert isinstance(languages, list)
         assert "python" in languages
         assert "javascript" in languages
         assert "java" in languages
 
     def test_is_language_supported(self, language_detector):
+        """Test checking if language is supported."""
         assert language_detector.is_language_supported("python")
+        assert language_detector.is_language_supported("javascript")
         assert not language_detector.is_language_supported("brainfuck")
 
 
 class TestDetectLanguageFunction:
+    """Tests for the detect_language convenience function."""
+
     def test_detect_language_python(self):
+        """Test detect_language function with Python."""
         result = detect_language("script.py", "def test(): pass")
         assert result == "python"
 
     def test_detect_language_unknown(self):
+        """Test detect_language function with unknown type and no content."""
         result = detect_language("file.xyz", "")
         assert result == "text" or result is None
+
+    def test_detect_language_from_filename_only(self):
+        """Test detect_language with filename only."""
+        result = detect_language("main.java")
+        assert result == "java"