Feat add circle area

src/arithmetic.py

@@ -4,6 +4,8 @@
 Python 3.6+ is required to run this module, since it uses type hints.
 """
 
+from math import pow
+
 
 def add(a: int | float, b: int | float) -> int | float:
     """Add two numbers."""
@@ -27,7 +29,7 @@ def divide(a: int | float, b: int | float) -> float:
 
 def power(a: int | float, b: int | float) -> int | float:
     """Raise a to the power of b."""
-    raise NotImplementedError("power is not implemented yet")
+    return pow(a, b)
 
 
 def factorial(n: int) -> int:

src/geometry.py

@@ -4,7 +4,7 @@
 
 from math import pi
 
-from .arithmetic import multiply
+from .arithmetic import multiply, power
 
 
 def rectangle_area(width: int | float, height: int | float) -> float:
@@ -30,6 +30,6 @@ def circle_circumference(radius: int | float) -> float:
 
 def circle_area(radius: int | float) -> float:
     """Calculate the area of a circle."""
-    raise NotImplementedError(
-        "circle_area is not implemented yet. Should be implmented only after src.arithmetic.power is implemented."
-    )
+    if radius < 0:
+        raise ValueError("Radius must be non-negative.")
+    return multiply(pi, power(radius, 2))

tests/test_arithmetic.py

@@ -4,7 +4,7 @@
 
 import pytest
 
-from src.arithmetic import add, divide, multiply, subtract
+from src.arithmetic import add, divide, multiply, power, subtract
 
 
 def test_add():
@@ -41,5 +41,12 @@ def test_divide_by_zero():
         divide(1, 0)
 
 
+def test_power():
+    """Test the power function."""
+    assert power(2, 3) == 8
+    assert power(0, 0) == 1
+    assert power(-1, 1) == -1
+
+
 if __name__ == "__main__":
     pytest.main()

tests/test_geometry.py

@@ -7,7 +7,12 @@
 import numpy as np
 import pytest
 
-from src.geometry import circle_circumference, rectangle_area, triangle_area
+from src.geometry import (
+    circle_area,
+    circle_circumference,
+    rectangle_area,
+    triangle_area,
+)
 
 
 def test_rectangle_area():
@@ -34,5 +39,13 @@ def test_circle_circumference():
         circle_circumference(-1)
 
 
+def test_circle_area():
+    """Test the circle_area function."""
+    assert np.isclose(circle_area(1), pi)
+    assert np.isclose(circle_area(0), 0)
+    with pytest.raises(ValueError):
+        circle_area(-1)
+
+
 if __name__ == "__main__":
     pytest.main()