Early errors for misuse of deprecation

It was too easy to accidentally misuse the field and enum deprecation API. This adds an early error explaining the correct form.

Closes #185

Author: leebyron

src/type/__tests__/validation.js

@@ -1653,4 +1653,37 @@ describe('Objects must adhere to Interface they implement', () => {
     );
   });
 
+  it('does not allow isDeprecated without deprecationReason on field', () => {
+    expect(() => {
+      var OldObject = new GraphQLObjectType({
+        name: 'OldObject',
+        fields: {
+          field: {
+            type: GraphQLString,
+            isDeprecated: true
+          }
+        }
+      });
+
+      return schemaWithFieldType(OldObject);
+    }).to.throw(
+      'OldObject.field should provide "deprecationReason" instead ' +
+      'of "isDeprecated".'
+    );
+  });
+
+  it('does not allow isDeprecated without deprecationReason on enum', () => {
+    expect(() =>
+      new GraphQLEnumType({
+        name: 'SomeEnum',
+        values: {
+          value: { isDeprecated: true }
+        }
+      })
+    ).to.throw(
+      'SomeEnum.value should provide "deprecationReason" instead ' +
+      'of "isDeprecated".'
+    );
+  });
+
 });

src/type/definition.js

@@ -388,6 +388,11 @@ function defineFieldMap(
       ...fieldMap[fieldName],
       name: fieldName
     };
+    invariant(
+      !field.hasOwnProperty('isDeprecated'),
+      `${type}.${fieldName} should provide "deprecationReason" instead ` +
+      `of "isDeprecated".`
+    );
     invariant(
       isOutputType(field.type),
       `${type}.${fieldName} field type must be Output Type but ` +
@@ -827,6 +832,11 @@ function defineEnumValues(
       `${type}.${valueName} must refer to an object with a "value" key ` +
       `representing an internal value but got: ${value}.`
     );
+    invariant(
+      !value.hasOwnProperty('isDeprecated'),
+      `${type}.${valueName} should provide "deprecationReason" instead ` +
+      `of "isDeprecated".`
+    );
     value.name = valueName;
     if (isNullish(value.value)) {
       value.value = valueName;