Added fix for is_nullish() that works with numpy arrays equality test (#60)

Author: coretl

src/graphql/pyutils/is_nullish.py

@@ -1,3 +1,4 @@
+import math
 from typing import Any
 
 from ..error import INVALID
@@ -7,4 +8,8 @@
 
 def is_nullish(value: Any) -> bool:
     """Return true if a value is null, undefined, or NaN."""
-    return value is None or value is INVALID or value != value
+    return (
+        value is None
+        or value is INVALID
+        or (isinstance(value, float) and math.isnan(value))
+    )

tests/pyutils/test_is_nullish.py

@@ -4,6 +4,22 @@
 from graphql.pyutils import is_nullish
 
 
+class FakeNumpyArray:
+    def __eq__(self, other):
+        # Numpy arrays return an array when compared with another numpy array
+        # containing the pointwise equality of the two
+        if isinstance(other, FakeNumpyArray):
+            return FakeNumpyArray()
+        else:
+            return False
+
+    def __bool__(self):
+        raise TypeError(
+            "The truth value of an array with more than one element is "
+            "ambiguous. Use a.any() or a.all()"
+        )
+
+
 def describe_is_nullish():
     def null_is_nullish():
         assert is_nullish(None) is True
@@ -29,3 +45,6 @@ def undefined_is_nullish():
 
     def nan_is_nullish():
         assert is_nullish(nan)
+
+    def numpy_arrays_are_not_nullish():
+        assert is_nullish(FakeNumpyArray()) is False