fix(NODE-6608): calculateObjectSize returns the wrong value for bigint

src/parser/calculate_size.ts

@@ -1,6 +1,6 @@
 import { Binary } from '../binary';
 import type { Document } from '../bson';
-import { BSONVersionError } from '../error';
+import { BSONError, BSONVersionError } from '../error';
 import * as constants from '../constants';
 import { ByteUtils } from '../utils/byte_utils';
 import { isAnyArrayBuffer, isDate, isRegExp } from './utils';
@@ -205,6 +205,13 @@ function calculateElement(
           1
         );
       }
+      return 0;
+    case 'bigint':
+      return (name != null ? ByteUtils.utf8ByteLength(name) + 1 : 0) + (8 + 1);
+    case 'symbol':
+      return 0;
+    default:
+      throw new BSONError(`Unrecognized JS type: ${typeof value}`);
   }
 
   return 0;

test/node/parser/calculate_size.test.ts

@@ -24,4 +24,16 @@ describe('calculateSize()', () => {
       })
     ).to.throw(BSONVersionError, /Unsupported BSON version/i);
   });
+
+  it('returns 8 bytes (+7 meta bytes) size for a bigint value', function () {
+    const doc = { a: BigInt(1) };
+    expect(BSON.calculateObjectSize(doc)).to.equal(16);
+    expect(BSON.calculateObjectSize(doc)).to.equal(BSON.serialize(doc).byteLength);
+  });
+
+  it('returns 0 bytes (+5 meta bytes) for a symbol value', function () {
+    const doc = { a: Symbol() };
+    expect(BSON.calculateObjectSize(doc)).to.equal(5);
+    expect(BSON.calculateObjectSize(doc)).to.equal(BSON.serialize(doc).byteLength);
+  });
 });