Add more serializer tests based on code coverage data

Description

Contributor guide

Tech stack

javascript

Domain

testing

Issue type

test

DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.

3

Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.

1-2 days

Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.

stale

ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.

clear

Prerequisites

basic JavaScript testingcode coverage concepts

Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.

40

Research direction

Investigate the current code coverage data for Prepack, likely using Istanbul or similar tooling. Focus on serializer files (e.g., src/serializer/). Write tests that cover untested branches and edge cases. Look at existing test patterns in the test directory to ensure consistency.