python_api: handle array-like args in approx() (#8137)

testing/python/approx.py

@@ -447,6 +447,36 @@ class TestApprox:
         assert a12 != approx(a21)
         assert a21 != approx(a12)
 
+    def test_numpy_array_protocol(self):
+        """
+        array-like objects such as tensorflow's DeviceArray are handled like ndarray.
+        See issue #8132
+        """
+        np = pytest.importorskip("numpy")
+
+        class DeviceArray:
+            def __init__(self, value, size):
+                self.value = value
+                self.size = size
+
+            def __array__(self):
+                return self.value * np.ones(self.size)
+
+        class DeviceScalar:
+            def __init__(self, value):
+                self.value = value
+
+            def __array__(self):
+                return np.array(self.value)
+
+        expected = 1
+        actual = 1 + 1e-6
+        assert approx(expected) == DeviceArray(actual, size=1)
+        assert approx(expected) == DeviceArray(actual, size=2)
+        assert approx(expected) == DeviceScalar(actual)
+        assert approx(DeviceScalar(expected)) == actual
+        assert approx(DeviceScalar(expected)) == DeviceScalar(actual)
+
     def test_doctests(self, mocked_doctest_runner) -> None:
         import doctest