Add test for custom scalars (#93)

Author: Cito

tests/type/test_custom_scalars.py

@@ -0,0 +1,195 @@
+from typing import Any, Dict, NamedTuple
+
+from graphql import graphql_sync
+from graphql.error import GraphQLError
+from graphql.language import ValueNode
+from graphql.pyutils import inspect, is_finite
+from graphql.type import (
+    GraphQLArgument,
+    GraphQLField,
+    GraphQLFloat,
+    GraphQLObjectType,
+    GraphQLScalarType,
+    GraphQLSchema,
+)
+from graphql.utilities import value_from_ast_untyped
+
+# this test is not (yet) part of GraphQL.js, see
+# https://github.com/graphql/graphql-js/issues/2657
+
+
+class Money(NamedTuple):
+    amount: float
+    currency: str
+
+
+def serialize_money(output_value: Any) -> Dict[str, float]:
+    if not isinstance(output_value, Money):
+        raise GraphQLError("Cannot serialize money value: " + inspect(output_value))
+    return output_value._asdict()
+
+
+def parse_money_value(input_value: Any) -> Money:
+    if not isinstance(input_value, Money):
+        raise GraphQLError("Cannot parse money value: " + inspect(input_value))
+    return input_value
+
+
+def parse_money_literal(value_node: ValueNode, variables=None) -> Money:
+    money = value_from_ast_untyped(value_node, variables)
+    if variables is not None and (
+        # variables are not set when checked with ValuesIOfCorrectTypeRule
+        not money
+        or not is_finite(money.get("amount"))
+        or not isinstance(money.get("currency"), str)
+    ):
+        raise GraphQLError("Cannot parse literal money value: " + inspect(money))
+    return Money(**money)
+
+
+MoneyScalar = GraphQLScalarType(
+    name="Money",
+    serialize=serialize_money,
+    parse_value=parse_money_value,
+    parse_literal=parse_money_literal,
+)
+
+
+def resolve_balance(root, _info):
+    return root
+
+
+def resolve_to_euros(_root, _info, money):
+    amount = money.amount
+    currency = money.currency
+    if not amount or currency == "EUR":
+        return amount
+    if currency == "DM":
+        return amount * 0.5
+    raise ValueError("Cannot convert to euros: " + inspect(money))
+
+
+schema = GraphQLSchema(
+    query=GraphQLObjectType(
+        name="RootQueryType",
+        fields={
+            "balance": GraphQLField(MoneyScalar, resolve=resolve_balance),
+            "toEuros": GraphQLField(
+                GraphQLFloat,
+                args={"money": GraphQLArgument(MoneyScalar)},
+                resolve=resolve_to_euros,
+            ),
+        },
+    )
+)
+
+
+def describe_custom_scalar():
+    def serialize():
+        source = """
+            {
+              balance
+            }
+            """
+
+        result = graphql_sync(schema, source, root_value=Money(42, "DM"))
+        assert result == ({"balance": {"amount": 42, "currency": "DM"}}, None)
+
+    def serialize_with_error():
+        source = """
+            {
+              balance
+            }
+            """
+
+        result = graphql_sync(schema, source, root_value=21)
+        assert result == (
+            {"balance": None},
+            [
+                {
+                    "message": "Cannot serialize money value: 21",
+                    "locations": [(3, 15)],
+                    "path": ["balance"],
+                }
+            ],
+        )
+
+    def parse_value():
+        source = """
+            query Money($money: Money!) {
+              toEuros(money: $money)
+            }
+            """
+
+        result = graphql_sync(
+            schema, source, variable_values={"money": Money(24, "EUR")}
+        )
+        assert result == ({"toEuros": 24}, None)
+
+        result = graphql_sync(
+            schema, source, variable_values={"money": Money(42, "DM")}
+        )
+        assert result == ({"toEuros": 21}, None)
+
+    def parse_value_with_error():
+        source = """
+            query Money($money: Money!) {
+              toEuros(money: $money)
+            }
+            """
+
+        result = graphql_sync(
+            schema, source, variable_values={"money": Money(42, "USD")}
+        )
+        assert result == (
+            {"toEuros": None},
+            [
+                {
+                    "message": "Cannot convert to euros: (42, 'USD')",
+                    "locations": [(3, 15)],
+                }
+            ],
+        )
+
+        result = graphql_sync(schema, source, variable_values={"money": 21})
+        assert result == (
+            None,
+            [
+                {
+                    "message": "Variable '$money' got invalid value 21;"
+                    " Cannot parse money value: 21",
+                    "locations": [(2, 25)],
+                }
+            ],
+        )
+
+    def parse_literal():
+        source = """
+            query Money($amount: Float!, $currency: String!) {
+              toEuros(money: {amount: $amount, currency: $currency})
+            }
+            """
+
+        variable_values = {"amount": 42, "currency": "DM"}
+        result = graphql_sync(schema, source, variable_values=variable_values)
+        assert result == ({"toEuros": 21}, None)
+
+    def parse_literal_with_errors():
+        source = """
+            query Money($amount: String!, $currency: Float!) {
+              toEuros(money: {amount: $amount, currency: $currency})
+            }
+            """
+
+        variable_values = {"amount": "DM", "currency": 42}
+        result = graphql_sync(schema, source, variable_values=variable_values)
+        assert result == (
+            {"toEuros": None},
+            [
+                {
+                    "message": "Argument 'money' has invalid value"
+                    " {amount: $amount, currency: $currency}.",
+                    "locations": [(3, 30)],
+                },
+            ],
+        )