validation code moved over and updated to meet new naming conventions. test coverage not passing.

Author: twof

src/validation/__tests__/harness.ts

@@ -2,6 +2,7 @@ import { expectJSON } from '../../__testUtils__/expectJSON';
 
 import type { Maybe } from '../../jsutils/Maybe';
 
+import type { ParseOptions } from '../../language/parser';
 import { parse } from '../../language/parser';
 
 import type { GraphQLSchema } from '../../type/schema';
@@ -119,17 +120,24 @@ export function expectValidationErrorsWithSchema(
   schema: GraphQLSchema,
   rule: ValidationRule,
   queryStr: string,
+  parseOptions?: ParseOptions,
 ): any {
-  const doc = parse(queryStr);
+  const doc = parse(queryStr, parseOptions);
   const errors = validate(schema, doc, [rule]);
   return expectJSON(errors);
 }
 
 export function expectValidationErrors(
   rule: ValidationRule,
   queryStr: string,
+  parseOptions?: ParseOptions,
 ): any {
-  return expectValidationErrorsWithSchema(testSchema, rule, queryStr);
+  return expectValidationErrorsWithSchema(
+    testSchema,
+    rule,
+    queryStr,
+    parseOptions,
+  );
 }
 
 export function expectSDLValidationErrors(

src/validation/rules/OverlappingFieldsCanBeMergedRule.ts

@@ -28,6 +28,7 @@ import {
   isObjectType,
 } from '../../type/definition';
 
+import { applyRequiredStatus } from '../../utilities/applyRequiredStatus';
 import { sortValueNode } from '../../utilities/sortValueNode';
 import { typeFromAST } from '../../utilities/typeFromAST';
 
@@ -605,17 +606,22 @@ function findConflict(
   const type1 = def1?.type;
   const type2 = def2?.type;
 
-  if (type1 && type2 && doTypesConflict(type1, type2)) {
-    return [
-      [
-        responseName,
-        `they return conflicting types "${inspect(type1)}" and "${inspect(
-          type2,
-        )}"`,
-      ],
-      [node1],
-      [node2],
-    ];
+  if (type1 && type2) {
+    const modifiedType1 = applyRequiredStatus(type1, node1.nullabilityAssertion);
+    const modifiedType2 = applyRequiredStatus(type2, node2.nullabilityAssertion);
+
+    if (doTypesConflict(modifiedType1, modifiedType2)) {
+      return [
+        [
+          responseName,
+          `they return conflicting types "${inspect(
+            modifiedType1,
+          )}" and "${inspect(modifiedType2)}"`,
+        ],
+        [node1],
+        [node2],
+      ];
+    }
   }
 
   // Collect and compare sub-fields. Use the same "visited fragment names" list