Speed up createNext test suite isolation

[timneutkens]

What?

Before: 25.71s

After: 11.05s (-57%)

How?

Currently the system for isolation looks like this:

• Copy packages folder to an isolated directory
• Run pnpm pack for all folders in packages
• Collect the pack files, add them as dependencies in package.json of the isolated application
• Run pnpm install

Because the next-swc (Turbopack + SWC, yes we still need to rename the package) binary file is quite large in development (900MB+) it means we have to copy, then zip (pnpm pack), then unzip (pnpm install) that binary, which takes about 3+ seconds in each step.

The change in this PR is to skip the copy/zip/unzip completely by providing the folder path for the binary directly to Next.js, as it's a binary we don't need the special isolation for this, it's already standalone so running it directly allows us to skip 14,6 seconds of work that is required for each isolated test in development.

This will likely have little effect on CI times as we already do some tricks like only running the packing at the start of the CI process. Only thing that could be better and is probably worth doing is adopting this change for the time it saves for unzipping, that's almost 4 seconds per test still.

Closes NEXT-3200

[timneutkens]

• Speed up createNext test suite isolation #64909 👈
• canary

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[socket-security]

Removed dependencies detected. Learn more about Socket for GitHub ↗︎

🚮 Removed packages: npm/next@14.2.1

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[ijjk]

Failing test suites

Commit: 93a4d38

pnpm test-start test/e2e/app-dir/app-compilation/index.test.ts

• app dir > Loading > should render loading.js in initial html for slow page

Expand output

● app dir › Loading › should render loading.js in initial html for slow page

next build failed with code/signal 1

  89 |           if (code || signal)
  90 |             reject(
> 91 |               new Error(`next build failed with code/signal ${code || signal}`)
     |               ^
  92 |             )
  93 |           else resolve()
  94 |         })

  at ChildProcess.<anonymous> (lib/next-modes/next-start.ts:91:15)

Read more about building and testing Next.js in contributing.md.

[ijjk]

Tests Passed

[timneutkens]

This was causing another version of Next.js to be installed, i.e. 14.2.1 and as such caused conflicts and sometimes resolved to the older version incorrectly.

[huozhi]

Nice PR!