Added a unittest for detected programming language

tests/lang_detection_testcase.py

@@ -0,0 +1,26 @@
+import unittest
+
+from pypacter.programming_lang_detector import detect_language
+
+
+class TestProgrammingLanguageDetection(unittest.TestCase):
+    """
+    Test case for the language detection function.
+    """
+
+    def test_programming_lang_detector_functionality(self) -> None:
+        """
+        Test the programming_lang_detector function with a simple code snippet.
+        """
+        # Creating a simple Python code snippet
+        python_code_snippet = "print('Hello, world!')"
+
+        # Calling the detect_language function for output
+        detected_language = detect_language(python_code_snippet)
+
+        # Printing the language detected
+        assert "python" in detected_language.lower()
+
+
+if __name__ == "__main__":
+    unittest.main()