Add more test cases and fix bugs

utils.py

@@ -1,13 +1,16 @@
 import re
 
-_CLASS_FINDER = re.compile(r'^class ([A-Z].*)\(ABC\)')
+_CLASS_FINDER = re.compile(r'^\s*class\s+([A-Z][a-zA-Z0-9_]*)\s*\((?:ABC|object)\)\s*:\s*')
 
 
 def guess_classname(code: str) -> str:
-    if match := _CLASS_FINDER.search(code):
-        return match.group(1)
+    for line in code.splitlines():
+        if match := _CLASS_FINDER.search(line):
+            return match.group(1)
     raise ValueError('Cannot find classname in code. Expected a class definition like `class ClassName(ABC):`')
 
 
 def camel_to_snake(input: str) -> str:
-    return re.sub(r'(?<=[a-z])(?=[A-Z])|(?<=[A-Z])(?=[A-Z][a-z])|(?<=[a-z])(?=[A-Z]{2,})', '_', input).lower()
+    s1 = re.sub(r'(?<=[a-z])(?=[A-Z])|(?<=[A-Z])(?=[A-Z][a-z])', '_', input)
+    s2 = re.sub(r'([a-zA-Z])([0-9])', r'\1\2', s1)
+    return re.sub(r'([0-9])([A-Z])', r'\1_\2', s2).lower()

utils_test.py

@@ -17,6 +17,19 @@ def test_guess_classname_edge_case_lowercase(self):
         with self.assertRaises(ValueError):
             guess_classname(code)
 
+    def test_guess_classname_with_extra_whitespace(self):
+        code = "class   MyClass  (ABC)  : pass"
+        self.assertEqual(guess_classname(code), "MyClass")
+
+    def test_guess_classname_with_multiple_classes(self):
+        code = "class FirstClass(ABC): pass\nclass SecondClass(ABC): pass"
+        self.assertEqual(guess_classname(code), "FirstClass")
+
+    def test_guess_classname_with_complex_class_definition(self):
+        code = "class MyComplexClass(object, metaclass=MyMeta): pass"
+        with self.assertRaises(ValueError):
+            guess_classname(code)
+
     def test_camel_to_snake_edge_case(self):
         self.assertEqual(camel_to_snake(""), "")
         self.assertEqual(camel_to_snake("A"), "a")
@@ -30,3 +43,12 @@ def test_camel_to_snake_with_acronyms(self):
         self.assertEqual(camel_to_snake("MyID"), "my_id")
         self.assertEqual(camel_to_snake("SimpleXMLParser"), "simple_xml_parser")
         self.assertEqual(camel_to_snake("APIFlagsSet"), "api_flags_set")
+
+    def test_camel_to_snake_with_numbers(self):
+        self.assertEqual(camel_to_snake("MyClass1"), "my_class1")
+        self.assertEqual(camel_to_snake("MyClass123"), "my_class123")
+        self.assertEqual(camel_to_snake("Class123Name"), "class123_name")
+
+    def test_camel_to_snake_single_word(self):
+        self.assertEqual(camel_to_snake("hello"), "hello")
+        self.assertEqual(camel_to_snake("WORLD"), "world")