coerce_value: correctly handle nan and similar values

Replicates graphql/graphql-js@670bbac

Author: Cito

README.md

@@ -16,7 +16,7 @@ The current version 3.0.0a2 of GraphQL-core is up-to-date
 with GraphQL.js version 14.4.2.
 
 All parts of the API are covered by an extensive test suite
-of currently 1903 unit tests.
+of currently 1905 unit tests.
 
 
 ## Documentation

src/graphql/utilities/coerce_value.py

@@ -2,7 +2,7 @@
 
 from ..error import GraphQLError, INVALID
 from ..language import Node
-from ..pyutils import did_you_mean, inspect, is_invalid, suggestion_list
+from ..pyutils import did_you_mean, inspect, suggestion_list
 from ..type import (
     GraphQLEnumType,
     GraphQLInputObjectType,
@@ -63,7 +63,7 @@ def coerce_value(
         type_ = cast(GraphQLScalarType, type_)
         try:
             parse_result = type_.parse_value(value)
-            if is_invalid(parse_result):
+            if parse_result is INVALID:
                 return of_errors(
                     [coercion_error(f"Expected type {type_.name}", blame_node, path)]
                 )
@@ -137,8 +137,8 @@ def coerce_value(
         # Ensure every defined field is valid.
         for field_name, field in fields.items():
             field_value = value.get(field_name, INVALID)
-            if is_invalid(field_value):
-                if not is_invalid(field.default_value):
+            if field_value is INVALID:
+                if field.default_value is not INVALID:
                     # Use out name as name if it exists (extension of GraphQL.js).
                     coerced_value_dict[
                         field.out_name or field_name

tests/utilities/test_coerce_value.py

@@ -1,3 +1,4 @@
+from math import nan
 from typing import Any, List
 
 from graphql.error import INVALID
@@ -65,6 +66,10 @@ def returns_no_error_for_null_result():
             result = coerce_value({"value": None}, TestScalar)
             assert expect_value(result) is None
 
+        def returns_no_error_for_nan_result():
+            result = coerce_value({"value": nan}, TestScalar)
+            assert expect_value(result) is nan
+
         def returns_an_error_for_undefined_result():
             error = ValueError("Some error message")
             result = coerce_value({"error": error}, TestScalar)
@@ -117,10 +122,10 @@ def returns_an_error_for_a_non_dict_value():
             ]
 
         def returns_an_error_for_an_invalid_field():
-            result = coerce_value({"foo": "abc"}, TestInputObject)
+            result = coerce_value({"foo": nan}, TestInputObject)
             assert expect_errors(result) == [
                 "Expected type Int at value.foo."
-                " Int cannot represent non-integer value: 'abc'"
+                " Int cannot represent non-integer value: nan"
             ]
 
         def returns_multiple_errors_for_multiple_invalid_fields():
@@ -182,7 +187,11 @@ def describe_for_graphql_input_object_with_default_value():
         def _get_test_input_object(default_value):
             return GraphQLInputObjectType(
                 "TestInputObject",
-                {"foo": GraphQLInputField(GraphQLInt, default_value=default_value)},
+                {
+                    "foo": GraphQLInputField(
+                        GraphQLScalarType("TestScalar"), default_value=default_value
+                    )
+                },
             )
 
         def returns_no_errors_for_valid_input_value():
@@ -197,6 +206,12 @@ def returns_null_as_value():
             result = coerce_value({}, _get_test_input_object(None))
             assert expect_value(result) == {"foo": None}
 
+        def returns_nan_as_value():
+            result = coerce_value({}, _get_test_input_object(nan))
+            result_value = expect_value(result)
+            assert "foo" in result_value
+            assert result_value["foo"] is nan
+
     def describe_for_graphql_list():
         TestList = GraphQLList(GraphQLInt)