From 4c7cc73ae2ff27cc1b00bff079a9c4cfe1eee926 Mon Sep 17 00:00:00 2001
From: Khushi Pal <khushipaltwt@gmail.com>
Date: Thu, 19 Jun 2025 15:43:24 +0530
Subject: [PATCH 1/3] Add recursive factorial method with tests

---
 recursion/__init__.py             |  0
 recursion/factorial.py            | 28 ++++++++++++++++++++++++++++
 recursion/tests/__init__.py       |  0
 recursion/tests/test_factorial.py | 18 ++++++++++++++++++
 4 files changed, 46 insertions(+)
 create mode 100644 recursion/__init__.py
 create mode 100644 recursion/factorial.py
 create mode 100644 recursion/tests/__init__.py
 create mode 100644 recursion/tests/test_factorial.py

diff --git a/recursion/__init__.py b/recursion/__init__.py
new file mode 100644
index 000000000000..e69de29bb2d1
diff --git a/recursion/factorial.py b/recursion/factorial.py
new file mode 100644
index 000000000000..3150ce17bce3
--- /dev/null
+++ b/recursion/factorial.py
@@ -0,0 +1,28 @@
+"""
+Fibonacci
+https://en.wikipedia.org/wiki/Fibonacci_number
+"""
+def factorial(number: int) -> int:
+    """
+    Compute the factorial of a non-negative integer using recursion.
+
+    >>> factorial(5)
+    120
+    >>> factorial(0)
+    1
+    >>> factorial(1)
+    1
+    >>> factorial(3)
+    6
+    >>> factorial(10)
+    3628800
+    >>> factorial(-1)
+    Traceback (most recent call last):
+        ...
+    ValueError: Input must be a non-negative integer.
+    """
+    if number < 0:
+        raise ValueError("Input must be a non-negative integer.")
+    if number == 0:
+        return 1
+    return number * factorial(number - 1)
diff --git a/recursion/tests/__init__.py b/recursion/tests/__init__.py
new file mode 100644
index 000000000000..e69de29bb2d1
diff --git a/recursion/tests/test_factorial.py b/recursion/tests/test_factorial.py
new file mode 100644
index 000000000000..13cf907491e2
--- /dev/null
+++ b/recursion/tests/test_factorial.py
@@ -0,0 +1,18 @@
+import unittest
+from recursion.factorial import factorial
+
+
+class TestFactorial(unittest.TestCase):
+    def test_factorial_valid_inputs(self):
+        self.assertEqual(factorial(0), 1)
+        self.assertEqual(factorial(1), 1)
+        self.assertEqual(factorial(5), 120)
+        self.assertEqual(factorial(10), 3628800)
+
+    def test_factorial_invalid_input(self):
+        with self.assertRaises(ValueError):
+            factorial(-1)
+
+
+if __name__ == "__main__":
+    unittest.main()

From 137dda1a8c507f5a5b5ea1c6530977a44ff58ec4 Mon Sep 17 00:00:00 2001
From: "pre-commit-ci[bot]"
 <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Date: Thu, 19 Jun 2025 10:35:17 +0000
Subject: [PATCH 2/3] [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci
---
 recursion/factorial.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/recursion/factorial.py b/recursion/factorial.py
index 3150ce17bce3..0fe09e2005bf 100644
--- a/recursion/factorial.py
+++ b/recursion/factorial.py
@@ -2,6 +2,8 @@
 Fibonacci
 https://en.wikipedia.org/wiki/Fibonacci_number
 """
+
+
 def factorial(number: int) -> int:
     """
     Compute the factorial of a non-negative integer using recursion.

From 9696330432148d50b29d08e699c41ce1e462a7dc Mon Sep 17 00:00:00 2001
From: Khushi Pal <114483555+khushipy@users.noreply.github.com>
Date: Thu, 19 Jun 2025 17:03:47 +0530
Subject: [PATCH 3/3] Update test_factorial.py

---
 recursion/tests/test_factorial.py | 23 ++++++++++-------------
 1 file changed, 10 insertions(+), 13 deletions(-)

diff --git a/recursion/tests/test_factorial.py b/recursion/tests/test_factorial.py
index 13cf907491e2..91bcc2bb2c61 100644
--- a/recursion/tests/test_factorial.py
+++ b/recursion/tests/test_factorial.py
@@ -1,18 +1,15 @@
-import unittest
-from recursion.factorial import factorial
+import pytest
 
+from recursion.factorial import factorial
 
-class TestFactorial(unittest.TestCase):
-    def test_factorial_valid_inputs(self):
-        self.assertEqual(factorial(0), 1)
-        self.assertEqual(factorial(1), 1)
-        self.assertEqual(factorial(5), 120)
-        self.assertEqual(factorial(10), 3628800)
 
-    def test_factorial_invalid_input(self):
-        with self.assertRaises(ValueError):
-            factorial(-1)
+def test_factorial_valid_inputs() -> None:
+    assert factorial(0) == 1
+    assert factorial(1) == 1
+    assert factorial(5) == 120
+    assert factorial(10) == 3628800
 
 
-if __name__ == "__main__":
-    unittest.main()
+def test_factorial_invalid_input() -> None:
+    with pytest.raises(ValueError):
+        factorial(-1)