Implement Recursive Array Flattening Function with Comprehensive Tests

src/array_utils.py

@@ -0,0 +1,26 @@
+from typing import List, Union, Any
+
+def flatten_array(arr: Union[List[Any], Any]) -> List[Any]:
+    """
+    Recursively flatten a nested list/array into a single-level list.
+
+    Args:
+        arr (Union[List[Any], Any]): The input array to be flattened.
+
+    Returns:
+        List[Any]: A flattened list containing all non-list elements.
+
+    Raises:
+        TypeError: If the input is not a list or does not support iteration.
+    """
+    # Base case: if input is not a list or is a string, return as single-element list
+    if not isinstance(arr, list) or isinstance(arr, str):
+        return [arr]
+
+    # Recursive flattening
+    flattened = []
+    for item in arr:
+        # Recursively flatten each item and extend the result
+        flattened.extend(flatten_array(item))
+
+    return flattened

tests/test_array_utils.py

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+import pytest
+from src.array_utils import flatten_array
+
+def test_flatten_simple_list():
+    """Test flattening a simple list"""
+    assert flatten_array([1, 2, 3]) == [1, 2, 3]
+
+def test_flatten_nested_list():
+    """Test flattening a nested list"""
+    assert flatten_array([1, [2, 3], 4]) == [1, 2, 3, 4]
+
+def test_flatten_deeply_nested_list():
+    """Test flattening a deeply nested list"""
+    assert flatten_array([1, [2, [3, 4]], 5]) == [1, 2, 3, 4, 5]
+
+def test_flatten_multiple_levels_of_nesting():
+    """Test flattening multiple levels of nested lists"""
+    nested = [1, [2, [3, [4, 5]]], 6]
+    assert flatten_array(nested) == [1, 2, 3, 4, 5, 6]
+
+def test_flatten_mixed_types():
+    """Test flattening a list with mixed types"""
+    mixed = [1, 'a', [2, [3.14]], {'key': 'value'}]
+    assert flatten_array(mixed) == [1, 'a', 2, 3.14, {'key': 'value'}]
+
+def test_flatten_empty_list():
+    """Test flattening an empty list"""
+    assert flatten_array([]) == []
+
+def test_flatten_non_nested_element():
+    """Test flattening a non-nested element"""
+    assert flatten_array(42) == [42]
+
+def test_flatten_string():
+    """Test that strings are treated as single elements"""
+    assert flatten_array('hello') == ['hello']