Add additional test, written by @spawnia

src/type/__tests__/validation-test.js

@@ -761,6 +761,46 @@ describe('Type System: Input Objects must have fields', () => {
     ]);
   });
 
+  it('rejects Input Objects with multiple non-breakable circular reference', () => {
+    const schema = buildSchema(`
+      type Query {
+        field(arg: SomeInputObject): String
+      }
+
+      input SomeInputObject {
+        startLoop: AnotherInputObject!
+      }
+
+      input AnotherInputObject {
+        closeLoop: SomeInputObject!
+        startSecondLoop: YetAnotherInputObject!
+      }
+
+      input YetAnotherInputObject {
+        closeSecondLoop: AnotherInputObject!
+        nonNullSelf: YetAnotherInputObject!
+      }
+    `);
+
+    expect(validateSchema(schema)).to.deep.equal([
+      {
+        message:
+          'Cannot reference Input Object "SomeInputObject" within itself through a series of non-null fields: "startLoop.closeLoop".',
+        locations: [{ line: 7, column: 9 }, { line: 11, column: 9 }],
+      },
+      {
+        message:
+          'Cannot reference Input Object "AnotherInputObject" within itself through a series of non-null fields: "startSecondLoop.closeSecondLoop".',
+        locations: [{ line: 12, column: 9 }, { line: 16, column: 9 }],
+      },
+      {
+        message:
+          'Cannot reference Input Object "YetAnotherInputObject" within itself through a series of non-null fields: "nonNullSelf".',
+        locations: [{ line: 17, column: 9 }],
+      },
+    ]);
+  });
+
   it('rejects an Input Object type with incorrectly typed fields', () => {
     const schema = buildSchema(`
       type Query {