Implement Recursive Array Flattening Function with Comprehensive Test Coverage

src/array_utils.py

@@ -0,0 +1,36 @@
+from typing import List, Union, Any
+
+def flatten_array(arr: Union[List[Any], Any]) -> List[Any]:
+    """
+    Recursively flatten a nested array into a single-level array.
+
+    Args:
+        arr (Union[List[Any], Any]): The input array to flatten. 
+               Can contain nested lists or other types of elements.
+
+    Returns:
+        List[Any]: A flattened list containing all non-list elements.
+
+    Examples:
+        >>> flatten_array([1, [2, 3], [4, [5, 6]]])
+        [1, 2, 3, 4, 5, 6]
+        >>> flatten_array([])
+        []
+        >>> flatten_array([1, 2, 3])
+        [1, 2, 3]
+    """
+    # Base case: if input is not a list, return it as a single-element list
+    if not isinstance(arr, list):
+        return [arr]
+
+    # If the list is empty, return an empty list
+    if not arr:
+        return []
+
+    # Recursive flattening
+    flattened = []
+    for item in arr:
+        # Recursively flatten each item
+        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 list with one level of nesting"""
+    assert flatten_array([1, [2, 3], 4]) == [1, 2, 3, 4]
+
+def test_flatten_deeply_nested_list():
+    """Test flattening a list with multiple levels of nesting"""
+    assert flatten_array([1, [2, [3, 4]], [5, 6]]) == [1, 2, 3, 4, 5, 6]
+
+def test_flatten_empty_list():
+    """Test flattening an empty list"""
+    assert flatten_array([]) == []
+
+def test_flatten_single_element():
+    """Test flattening a single non-list element"""
+    assert flatten_array(5) == [5]
+
+def test_flatten_mixed_types():
+    """Test flattening a list with mixed types and nesting"""
+    assert flatten_array([1, [2, 'three'], [4.5, [None]]]) == [1, 2, 'three', 4.5, None]
+
+def test_flatten_complex_nesting():
+    """Test flattening a list with complex, irregular nesting"""
+    assert flatten_array([1, [2, [3, [4]]], 5, [6], [[7]]]) == [1, 2, 3, 4, 5, 6, 7]