Repository navigation
withArgs stops matching Buffers by content in 21.0.2 (samsam major bump in patch release) #2678
Description
Describe the bug
stub.withArgs() no longer matches Buffer arguments by content when called with a different reference holding the same bytes. This regression was introduced in 21.0.2.
To Reproduce
const sinon = require('sinon')
const buf1 = Buffer.from([255, 216, 255, 224])
const buf2 = Buffer.from([255, 216, 255, 224]) // same content, different reference
const stub = sinon.stub()
stub.withArgs({ buffer: buf1 }).returns('ok')
console.log(stub({ buffer: buf2 }))
// sinon@21.0.1 → 'ok'
// sinon@21.0.2 → undefinedExpected behavior
withArgs should match Buffer instances with equal content, as it did in 21.0.1.
Screenshots
N/A
Context:
- Sinon version: 21.0.2 (broken), verified working on 21.0.1
- Runtime: Node 22.14.0
- Output of
npx envinfo --browsers --binaries:
Binaries:
Node: 22.14.0 - /usr/local/.nvm/versions/node/v22.14.0/bin/node
Yarn: 4.9.2 - /usr/local/.nvm/versions/node/v22.14.0/bin/yarn
npm: 10.9.2 - /usr/local/.nvm/versions/node/v22.14.0/bin/npm
bun: 1.2.23 - /usr/local/.bun/bin/bun
Browsers:
Chrome: 145.0.7632.159
Firefox: 148.0
Firefox Developer Edition: 148.0
- Other relevant environmental info: the root cause is a dependency bump in sinon's own package.json between 21.0.1 and 21.0.2:
21.0.1 → "@sinonjs/samsam": "^8.0.3"
21.0.2 → "@sinonjs/samsam": "^9.0.2" - A major samsam version was introduced in a patch sinon release, which violates semver and silently breaks any project using "sinon": "^21.0.0" on the next install.
- Other libraries you are using: none required to reproduce
- Example URL: N/A
Additional context:
Suggested fix: revert the samsam bump in a 21.0.3 patch, or re-release with a minor/major version bump to properly signal the breaking change.
Workaround in the meantime: pin sinon to 21.0.1.
Activity
mattbaileyuk commentedon Mar 10, 2026
We're having the same problem with
.calledWith()where the contents has a Buffer, so it does look like there's a matching issue withsamsam@9; if we override@sinonjs/samsaminpackage.jsonback to 8.0.3 then our failing test cases work again.Agree it feels like it should be rolled back for a 21.0.3, and then breaking changes handled in a new major version of
sinon.mattbaileyuk commentedon Mar 10, 2026
I've raised sinonjs/samsam#289 as I was able to put together a simple recreate in
samsamfatso83 commentedon Mar 16, 2026
Fix coming up shortly. Ref #2681 (comment)
fatso83 commentedon Mar 16, 2026
Fix from sinonjs/samsam#291 released . Running
rm -r node_modules/@sinonjs/*; npm installshould fix it, as will bump the patch version of the package.fatso83 commentedon Mar 16, 2026
Not releasing new major version as this was an unintended breakage. Hopefully the new tests put in place into samsam should catch future regressions.
fix(#2678): upgrade samsam to fix buffer comparisons