Fixed Bug Regarding Attribute Error in pytest.approx For Types Implicitly Convertible to Numpy Arrays

AUTHORS

@@ -321,6 +321,7 @@ Pierre Sassoulas
 Pieter Mulder
 Piotr Banaszkiewicz
 Piotr Helm
+Poulami Sau
 Prakhar Gurunani
 Prashant Anand
 Prashant Sharma

changelog/12114.bugfix.rst

@@ -0,0 +1 @@
+Fixed attribute error in pytest.approx for types implicitly convertible to numpy arrays by converting other_side to a numpy array so that np_array_shape != other_side.shape can be properly checked.

src/_pytest/python_api.py

@@ -163,6 +163,9 @@ def get_value_from_nested_list(
             self._approx_scalar, self.expected.tolist()
         )
 
+        # convert other_side to numpy array to ensure shape attribute is available
+        other_side = _as_numpy_array(other_side)
+
         if np_array_shape != other_side.shape:
             return [
                 "Impossible to compare arrays with different shapes.",

testing/python/approx.py

@@ -763,6 +763,23 @@ def test_numpy_array_wrong_shape(self):
         assert a12 != approx(a21)
         assert a21 != approx(a12)
 
+    def test_numpy_array_implicit_conversion(self):
+        np = pytest.importorskip("numpy")
+
+        class ImplicitArray:
+            """Type which is implicitly convertible to a numpy array."""
+
+            def __init__(self, vals):
+                self.vals = vals
+
+            def __array__(self, dtype=None, copy=None):
+                return np.array(self.vals)
+
+        vec1 = ImplicitArray([1.0, 2.0, 3.0])
+        vec2 = ImplicitArray([1.0, 2.0, 4.0])
+        # see issue #12114 for test case
+        assert vec1 != approx(vec2)
+
     def test_numpy_array_protocol(self):
         """
         array-like objects such as tensorflow's DeviceArray are handled like ndarray.