enhance(astFromValueUntyped): respect toJSON

.changeset/few-parents-love.md

@@ -0,0 +1,5 @@
+---
+"@graphql-tools/utils": patch
+---
+
+Respect JS `Date` in `astFromValueUntyped`

packages/utils/src/astFromValueUntyped.ts

@@ -41,8 +41,8 @@ export function astFromValueUntyped(value: any): ValueNode | null {
   }
 
   if (typeof value === 'object') {
-    if (value instanceof Date) {
-      return { kind: Kind.STRING, value: value.toISOString() };
+    if (value?.toJSON) {
+      return astFromValueUntyped(value.toJSON());
     }
     const fieldNodes: Array<ObjectFieldNode> = [];
     for (const fieldName in value) {

packages/utils/tests/astFromValueUntyped.test.ts

@@ -0,0 +1,19 @@
+import { Kind, valueFromASTUntyped } from 'graphql';
+import { astFromValueUntyped } from '../src/astFromValueUntyped.js';
+
+describe('astFromValueUntyped', () => {
+  it('supports Date', () => {
+    const date = new Date();
+    const ast = astFromValueUntyped(date);
+    expect(ast).toEqual({
+      kind: Kind.STRING,
+      value: date.toISOString(),
+    });
+  });
+  it('supports Buffer', () => {
+    const buffer = Buffer.from('test');
+    const ast = astFromValueUntyped(buffer);
+    const generatedValue = valueFromASTUntyped(ast!);
+    expect(generatedValue).toMatchObject(buffer.toJSON());
+  });
+});