fix(NODE-6608): calculateObjectSize returns the wrong value for bigint (#742)

Author: nbbeeken

Diff for: .evergreen/config.yml

@@ -131,8 +131,10 @@ tasks:
       - func: fetch source
         vars:
           NODE_LTS_VERSION: 16
+          NPM_VERSION: 9
       - func: install dependencies
         vars:
+          NODE_LTS_VERSION: 16
           NPM_VERSION: 9
       - func: run tests
         vars:
@@ -143,6 +145,7 @@ tasks:
       - func: fetch source
         vars:
           NODE_LTS_VERSION: 18
+          NPM_VERSION: 10
       - func: install dependencies
       - func: run tests
         vars:
@@ -246,6 +249,7 @@ tasks:
         vars:
           # This needs to stay pinned at Node v18.16.0 for consistency across perf runs.
           NODE_LTS_VERSION: v18.16.0
+          NPM_VERSION: 9
       - func: install dependencies
         vars:
           NPM_VERSION: 9
@@ -262,6 +266,7 @@ tasks:
         vars:
           # This needs to stay pinned at Node v18.16.0 for consistency across perf runs.
           NODE_LTS_VERSION: v18.16.0
+          NPM_VERSION: 9
       - func: install dependencies
         vars:
           NPM_VERSION: 9
@@ -275,6 +280,7 @@ tasks:
         vars:
           # This needs to stay pinned at Node v18.16.0 for consistency across perf runs.
           NODE_LTS_VERSION: v18.16.0
+          NPM_VERSION: 9
       - func: install dependencies
         vars:
           NPM_VERSION: 9

Diff for: .evergreen/prepare-shell.sh

@@ -33,12 +33,14 @@ cat <<EOT > expansion.yml
 CURRENT_VERSION: "$CURRENT_VERSION"
 PROJECT_DIRECTORY: "$PROJECT_DIRECTORY"
 NODE_LTS_VERSION: "$NODE_LTS_VERSION"
+NPM_VERSION: "$NPM_VERSION"
 DRIVERS_TOOLS: "$DRIVERS_TOOLS"
 PREPARE_SHELL: |
     set -o errexit
     set -o xtrace
     export PROJECT_DIRECTORY="$PROJECT_DIRECTORY"
     export NODE_LTS_VERSION="$NODE_LTS_VERSION"
+    export NPM_VERSION="$NPM_VERSION"
     export DRIVERS_TOOLS="$DRIVERS_TOOLS"
 EOT
 # See what we've done

Diff for: 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;

Diff for: test/node/parser/calculate_size.test.ts

@@ -24,4 +24,26 @@ describe('calculateSize()', () => {
       })
     ).to.throw(BSONVersionError, /Unsupported BSON version/i);
   });
+
+  describe('when given a bigint value with a single character key', function () {
+    beforeEach(function () {
+      if (BSON.__noBigInt__) {
+        this.currentTest?.skip();
+      }
+    });
+
+    it('returns 8 bytes (+4 bytes for document size + 1 type byte + 1 byte for "a" + 2 null terminators)', function () {
+      const doc = { a: BigInt(1) };
+      expect(BSON.calculateObjectSize(doc)).to.equal(8 + 4 + 1 + 1 + 1 + 1);
+      expect(BSON.calculateObjectSize(doc)).to.equal(BSON.serialize(doc).byteLength);
+    });
+  });
+
+  describe('when given a symbol value with a single character key', function () {
+    it('returns 0 bytes (+4 bytes for document size + 1 null terminator)', function () {
+      const doc = { a: Symbol() };
+      expect(BSON.calculateObjectSize(doc)).to.equal(4 + 1);
+      expect(BSON.calculateObjectSize(doc)).to.equal(BSON.serialize(doc).byteLength);
+    });
+  });
 });