Type pytest.approx

Author: MarcoGorelli

changelog/14373.improvement.rst

@@ -0,0 +1 @@
+Added type annotations for ``pytest.approx``.

src/_pytest/python_api.py

@@ -558,7 +558,12 @@ def __repr__(self) -> str:
         return f"{self.expected} ± {tol_str}"
 
 
-def approx(expected, rel=None, abs=None, nan_ok: bool = False) -> ApproxBase:
+def approx(
+    expected: Any,
+    rel: float | Decimal | None = None,
+    abs: float | Decimal | None = None,
+    nan_ok: bool = False,
+) -> ApproxBase:
     """Assert that two numbers (or two ordered sequences of numbers) are equal to each other
     within some tolerance.
 

testing/python/approx.py

@@ -616,6 +616,8 @@ def test_decimal(self):
             assert a != approx(x, rel=Decimal("5e-7"), abs=0)
             assert approx(x, rel=Decimal("5e-6"), abs=0) == a
             assert approx(x, rel=Decimal("5e-7"), abs=0) != a
+            assert approx(x, rel=0, abs=Decimal("5e-3")) == a
+            assert approx(x, rel=0, abs=Decimal("5e-7")) != a
 
     def test_fraction(self):
         within_1e6 = [