oven-sh/bun

console.assert() with message should include "Assertion failed" alongside message

Open

#19953 opened on May 28, 2025

View on GitHub
 (6 comments) (0 reactions) (0 assignees)Rust (90,348 stars) (4,486 forks)batch import
bugconfirmed bugconsolegood first issue

Description

What version of Bun is running?

1.2.15-canary.63+df017990a

What platform is your computer?

Darwin 24.4.0 arm64 arm

What steps can reproduce the bug?

console.assert(false, "message");

What is the expected behavior?

$ node -e 'console.assert(false, "message")'
Assertion failed: message

What do you see instead?

$ bun -e 'console.assert(false, "message")'
message

If you are an automated agent, we have a streamlined process for merging agent PRs. Just add 🤖🤖🤖 to the end of the PR title to opt-in. Merging your PR will be fast-tracked.

Contributor guide

Tech stack
javascriptrust
Domain
backenddeveloper experience
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
JavaScriptRust
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
85
Research direction
Locate the implementation of console.assert in Bun's source code, likely in src/console or similar. The expected output when a message is provided should be 'Assertion failed: <message>', mirroring Node.js behavior. The fix involves modifying the formatting logic to prepend 'Assertion failed: ' when a message is present. Check existing tests for console.assert to ensure the change passes and add a test case for this scenario.