Mocha 12
Mocha 12 (sometimes “v12”) is an upcoming release of Mocha which updates internal dependencies while maintaining a stable end-user experience. There are no planned breaking changes between Mocha 11 and Mocha 12.
We released 11 unique betas through early April 2026, and I was personally aiming for a release candidate in early April and a full release in late April. However, I got super sick and am still not healthy as of 2026-04-08. We won’t get an RC until a few weeks after I’m healthy, whenever that is.
Dates and times are PDT (UTC-7). All links are to GitHub unless otherwise specified.
Remaining work
Items are ordered by ascending creation time.
- #5357: Mocha 12 Release Plan
- I asked about necessary docs on 2026-03-26
- I started drafting #5848: chore: add v12 release notes on 2026-04-02
- #5400: Repo: Switch from CJS to ESM internally
- Pelle started working on this one (2026-03-26)
- Pelle still drafting things offline, will work with him to get a clearer timeline (2026-04-02)
- I re-opened #5767: chore: migrate lib/pending and lib/error-constants to ESM as a first PR to ensure we are on the same page about implementation details after discussion with Pelle (2026-04-04)
Recently completed work
- #5763: Bug: beta versions should use semver-style dot numeric separator (instead of dash)
- I proposed a fix in the evening of 2026-03-26
- I fixed the fix, got it approved, then merged it on 2026-04-02
Removed from milestone
Currently removed from milestone
These issues weren’t super important for v12, and turned out to be more complicated than we thought, so I’ve pushed them to other milestones after a brief discussion. There’s a small chance they come back.
- #5335: Package: Bump supports-color from 8 to 10
- Asked to push out of v12 given weird complexities (2026-03-26)
- Best alternative is forking picocolors, which I think is a bit much, so I pushed this to 12.x (2026-04-02)
- #5471: feat: remove supports-color dependency
- Would replace #5335, called it out again in that issue on 2026-03-26
- Requires dependency PR to merge (picocolors#96: Don’t force-enable color if env.CI is set)
picocolorshasn’t been updated in 2+ years, asked maintainers publicly about forking it- Best alternative is forking picocolors, which I think is a bit much, so I pushed this to chores milestone (2026-04-02)
Definitely removed from milestone
- #5672: Bug: process.exit(0) ends mocha silently
- Has a fix PR (#5776: fix!: intercept process.exit during test execution) that I can review, but… (2026-03-26)
- Asked about landing this in v12 vs v13 given major release strategy (2026-03-26)
- We chose to move this to v13 on 2026-03-30
- #5835: refactor!: remove unused legacy errors.js functions
- Pelle opened this on 2026-03-31
- Josh noted that it had a breaking change on 2026-04-01
- I asked to move this to v13 on 2026-04-02 evening
- We moved this to v13 per discussion (2026-04-04 morning)
References
See also Mocha - markwiemer.com