fix(tests): keep Git from rewriting fixture line endings on Windows

[MohammedAlkindi]

Closes #181

Replaces #1449, reopened only to correct the source branch name. Same commit (fcff40e), same diff, body unchanged.

Symptom

On a clean clone on Windows, npm test gives 12 failing / 71 passing before any code is touched:

AssertionError [ERR_ASSERTION]: Expected values to be strictly equal:
1803 !== 1778

Cause

test/files/ holds opaque upload payloads whose exact byte size the suite hardcodes, and nothing marked them as binary. With core.autocrlf=true — Git's default on Windows — checkout rewrites LF to CRLF in the text-like fixtures:

fixture	committed blob	on disk after checkout
medium.dat	13196	13386
small0.dat	1778	1803
small1.dat	315	329
tiny0.dat	122	128
empty.dat, tiny1.dat	0, 7	unchanged (no line terminators)
large.jpg	2413677	unchanged (Git detects it as binary)

The committed blobs already hold exactly the LF bytes the tests expect — 1778 for small0.dat, matching every assert.strictEqual(..., 1778). Only the checkout conversion is wrong.

Fix

One .gitattributes marking test/files/** as binary. Because the blobs are already correct, suppressing the end-of-line conversion is sufficient on its own — the fixtures are not modified, so the hardcoded sizes stay valid and there is no fixture churn to review.

This follows the second option @jonchurch laid out on the issue — "changing the behavior of git with a .gitattributes file" — rather than @LinusU's original suggestion of regenerating the fixtures as random binary data. Both stop the conversion; this one leaves the recorded sizes and the fixtures themselves untouched. binary also implies -diff, which is what you want for opaque payloads.

I kept this to a single file on purpose: the previous attempt, #832, was closed after the feedback that it "changes too many things to be easily evaluated".

Deliberately unchanged

The 12th failure is a different bug and is not touched here. Functionality > should rename the destination directory to a different directory asserts req.files[0].path.indexOf('/testforme-') >= 0, hardcoding a forward slash as the path separator, so it can never match a Windows path regardless of line endings. It fails before and after this change. It deserves its own issue and PR.

Testing

Windows 11, Node v24.18.0, core.autocrlf=true.

	passing	failing
clean clone, before	71	12
with this change	79	1

The 11 fixed failures span disk-storage, functionality, memory-storage, reuse-middleware and select-field; the 1 remaining is the path-separator assertion above.

Verified end to end rather than only in place: after pushing this branch I made a fresh git clone of it on Windows and confirmed every fixture arrives at its committed size with no CR bytes, then ran npm install && npm test in that new clone — 79 passing, 1 failing. npm run lint (standard) is clean.

I have no way to run the macOS or Linux jobs locally; those platforms do not convert line endings on checkout, so their behaviour is unchanged by this, and CI is the authority.

[MohammedAlkindi]

For context: this supersedes #1449, which I closed after opening this. Nothing about the change differs — same commit fcff40e, same single .gitattributes file.

[UlisesGascon]

Thanks @MohammedAlkindi!