test: fix five type errors that landed beside #44614

[robobun]

Behaviour change: none

Problem

• On main e655c58, cd test && bun check reports Found 5 errors in 4 files, checked 2,639 files. tsc 7.0.2 reports the same five. Fix every type error in test/ #44614 says this tree has none.
• bun check - a TypeScript type checker builtin to Bun #44361, Upgrade WebKit to dbdca7545d #44615 and ByteStream: report a stored producer error and keep the taken prefix with the buffer #38003 added the five lines. They merged after the last push to Fix every type error in test/ #44614 and before its merge.

Fix

• Five edits in four files: two casts, as const, a parameter type, and ! on server.hostname and server.port.
• The transpiler erases each edit. bun build --no-bundle gives the same bytes for each file as on main.
• One cast is as any on Bun.write(s3file, response): bun-types has no overload for it. Fix every type error in test/ #44614 lists that gap and casts the same call in fetch-backpressure.test.ts.
• Verified: bun bd check and tsc 7.0.2 in test/ report no errors in 2,639 files. On a release build of e655c58, the edited tests pass, and so does s3-stream-error-gc.test.ts, which runs the fixture. Notes has every run.

Background

• Server#hostname and Server#port are undefined for a server on a unix socket. Other Bun.connect calls in bun-server.test.ts use ! for that.
• TypeScript's libraries have no name for the argument of Intl.DurationFormat#format. Intl.DurationInput does not exist.
• Considered the Bun.write overload here. It changes declarations that users see, so it needs its own PR with a fixture case (bun-types: declare bytes() on ShellPromise #44725).

Downsides

• The tree can get type errors again. No CI job type checks test/: .github/workflows/lint.yml checks scripts, src/js, src and src/runtime/bake.
• Bun.write(s3file, response) stays a type error for users until bun-types has the overload.

Notes

The five errors on main (bun check and tsc 7.0.2 print the same text)

cli/check/check.test.ts(298,33): error TS2345: Argument of type '{ "b.ts": string; "tsconfig.json"?: undefined; } | { "b.ts"?: undefined; "tsconfig.json": string; }' is not assignable to parameter of type 'Record<string, string>'.
cli/check/check.test.ts(464,77): error TS2322: Type '"" | NonSharedBuffer | undefined' is not assignable to type 'ArrayBufferView<ArrayBufferLike> | undefined'.
js/bun/http/bun-server.test.ts(2180,5): error TS2769: No overload matches this call.
js/bun/jsc/webkit-upgrade-dbdca7545d.test.ts(84,73): error TS2694: Namespace 'Intl' has no exported member 'DurationInput'.
js/bun/s3/s3-stream-stored-error-fixture.ts(79,15): error TS2769: No overload matches this call.

Each edit

Line on main	From	Edit
check.test.ts:298	#44361	[...] as Record<string, string>[]. The object literals in the array have different keys, so each member of the element type gets the keys of the others as ?: undefined. proxy-stress-matrix.test.ts:313 has the same cast from #44614.
check.test.ts:464	#44361	as const on the list of file names at line 458. For a string name, name && readFileSync(...) can be "". For the literal names it cannot. A cast at line 464 moves the object literal to three lines, and then the transpiled file differs in line breaks.
bun-server.test.ts:2180	#38003	server.hostname! and server.port!, as in lines 90 and 2122 of that file.
webkit-upgrade-dbdca7545d.test.ts:84	#44615	Parameters<Intl.DurationFormat["format"]>[0]. lib.es2025.intl.d.ts declares format(duration: Partial<Record<DurationFormatUnit, number>>).
s3-stream-stored-error-fixture.ts:79	#38003	client.file("copy") as any, as in fetch-backpressure.test.ts:1723. S3File#write and S3Client#write take a Response. Only Bun.write has no overload for it.

Type checks, in test/

Checker	main e655c58	this branch
bun bd check (debug build)	Found 5 errors in 4 files, checked 2,639 files	No type errors in 2,639 files
bun check, canary 1.4.3-canary.1+e655c5803	the same five	No type errors in 2,639 files
tsc 7.0.2 (typescript7 of test/package.json)	the same five	no errors
tsc 6.0.2 (bun run typecheck)	not run	2 errors, the TS2786 in jsx-dev.tsx and jsx-production.tsx that #44614 describes

Same JavaScript

bun build --no-bundle --target=bun <file>, with the file in its place so that test/tsconfig.json applies, on main and on this branch. The output is identical for all four files: 968,848 bytes for check.test.ts, 120,847 for bun-server.test.ts, 4,960 for webkit-upgrade-dbdca7545d.test.ts, 5,396 for s3-stream-stored-error-fixture.ts.

Test runs

Release build of e655c58 (the canary), on this branch:

• bun-server.test.ts: 81 pass, 1 skip.
• webkit-upgrade-dbdca7545d.test.ts: 9 pass, 1 todo.
• s3-stream-error-gc.test.ts, which runs the fixture: 4 pass.
• check.test.ts -t "what stops the type check says how many files it leaves" and -t "are those of TypeScript 7, byte for byte": both pass.
• All of check.test.ts, four runs on main and four on this branch, in turns: 8, 24, 7 and 10 tests fail on main, 8, 15, 5 and 14 on this branch. Each failure is the 5000 ms timeout, none is a failed assertion. My machine has 12 cores with a cap.

Debug build (bun bd test), on this branch:

• webkit-upgrade-dbdca7545d.test.ts: 9 pass, 1 todo. s3-stream-error-gc.test.ts: 4 pass.
• bun-server.test.ts: the edited test passes. 5 other tests reach the 5000 ms timeout. On main 13 do. They start a debug build of bun in a child process.
• check.test.ts -t "are those of TypeScript 7, byte for byte" passes.
• check.test.ts -t "what stops the type check says how many files it leaves" reaches the 5000 ms timeout in 3 of 3 runs, and in 2 of 2 runs on main. It starts bun nine times. With --timeout 120000 it passes in 13.1 s.

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no test proof · iteration 0 · platform-specific test(s) that do not run on this machine, deferring to CI, which covers all platforms: test/js/bun/http/bun-server.test.ts, test/cli/check/check.test.ts

[robobun]

Status: ready for review.

Reproduction

1. On main e655c58, run bun install in the repository root and in test/.
2. Run cd test && bun check with a build of that commit. ./node_modules/typescript7/bin/tsc --noEmit in test/ gives the same result.
3. On main it prints five errors and Found 5 errors in 4 files, checked 2,639 files:

   cli/check/check.test.ts(298,33): error TS2345
   cli/check/check.test.ts(464,77): error TS2322
   js/bun/http/bun-server.test.ts(2180,5): error TS2769
   js/bun/jsc/webkit-upgrade-dbdca7545d.test.ts(84,73): error TS2694
   js/bun/s3/s3-stream-stored-error-fixture.ts(79,15): error TS2769
   

4. On this branch it prints No type errors in 2,639 files.

PR: #44861

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

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📥 Commits

Reviewing files that changed from the base of the PR and between e655c58 and ac0030f.

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📒 Files selected for processing (4)

• test/cli/check/check.test.ts
• test/js/bun/http/bun-server.test.ts
• test/js/bun/jsc/webkit-upgrade-dbdca7545d.test.ts
• test/js/bun/s3/s3-stream-stored-error-fixture.ts

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Walkthrough

Test code updates adjust TypeScript expressions and types in CLI, HTTP, Intl, and S3 tests. The test cases and expected results remain unchanged.

Changes

Test Type Adjustments

Layer / File(s)	Summary
Test typing and expressions test/cli/check/check.test.ts, test/js/bun/http/bun-server.test.ts, test/js/bun/jsc/webkit-upgrade-dbdca7545d.test.ts, test/js/bun/s3/s3-stream-stored-error-fixture.ts	CLI tests parenthesize a mapped array and assert a dictionary-name array as const. The HTTP test adds non-null assertions. The Intl helper derives its parameter type from format, and the S3 test casts the file argument to any.

Suggested reviewers: jarred-sumner

Priority: ⬇️ Low

Merge Risk: ⚪ Minimal · up to ac003

The changes are limited to test typing and preserve test behavior; no production-impacting merge risk is evident.

🚥 Pre-merge checks | ✅ 4

✅ Passed checks (4 passed)

Check name	Status	Explanation
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.
Description check		The description clearly explains the five type errors, the four-file fix, verification results, test coverage, and known limitations. It does not use the exact template headings, but it provides the r…
Title check		The title clearly and concisely identifies the test-only change and its purpose: fixing five type errors related to #44614.

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[claude]

Code review found no issues

No high-confidence issues detected in this change.