feat: Add test_string.py

Author: yyossy5

test/basic/test_string.py

@@ -0,0 +1,59 @@
+"""
+Test module for string operations.
+"""
+
+import unittest
+
+from src.basic.string import extract_alphanumeric, reverse_string
+
+
+class TestString(unittest.TestCase):
+    """Test class for string operations"""
+
+    def test_reverse_string_basic(self):
+        """Test for basic string reversal"""
+        self.assertEqual(reverse_string("hello"), "olleh")
+        self.assertEqual(reverse_string("python"), "nohtyp")
+
+    def test_reverse_string_empty(self):
+        """Test for empty string"""
+        self.assertEqual(reverse_string(""), "")
+
+    def test_reverse_string_single_char(self):
+        """Test for single character string"""
+        self.assertEqual(reverse_string("a"), "a")
+
+    def test_reverse_string_japanese(self):
+        """Test for Japanese string"""
+        self.assertEqual(reverse_string("こんにちは"), "はちにんこ")
+
+    def test_reverse_string_with_spaces(self):
+        """Test for string with spaces"""
+        self.assertEqual(reverse_string("hello world"), "dlrow olleh")
+
+    def test_extract_alphanumeric_basic(self):
+        """Test for basic alphanumeric extraction"""
+        self.assertEqual(extract_alphanumeric("Hello123"), "Hello123")
+        self.assertEqual(extract_alphanumeric("Python3.9"), "Python39")
+
+    def test_extract_alphanumeric_with_spaces(self):
+        """Test for strings with spaces"""
+        self.assertEqual(extract_alphanumeric("Hello World 123"), "HelloWorld123")
+        self.assertEqual(extract_alphanumeric("   abc   123   "), "abc123")
+
+    def test_extract_alphanumeric_with_special_chars(self):
+        """Test for strings with special characters"""
+        self.assertEqual(extract_alphanumeric("Hello@World!123"), "HelloWorld123")
+        self.assertEqual(extract_alphanumeric("$#@123abc!?"), "123abc")
+
+    def test_extract_alphanumeric_empty(self):
+        """Test for empty string"""
+        self.assertEqual(extract_alphanumeric(""), "")
+
+    def test_extract_alphanumeric_no_alphanumeric(self):
+        """Test for string with no alphanumeric characters"""
+        self.assertEqual(extract_alphanumeric("@#$%^&*()"), "")
+
+    def test_extract_alphanumeric_japanese_and_alphanumeric(self):
+        """Test for string with Japanese and alphanumeric characters"""
+        self.assertEqual(extract_alphanumeric("こんにちは123ABC"), "123ABC")