This PR improves the integration tests in two ways:
1. Make the integration tests more reliable and thus less flakey
2. Make the integration tests faster (by introducing concurrency)
Tried a lot of different things to make sure that these tests are fast
and stable.
---
The biggest issue we noticed is that some tests are flakey, these are
tests with long running dev-mode processes where watchers are being used
and/or dev servers are created.
To solve this, all the tests that spawn a process look at stdout/stderr
and wait for a message from the process to know whether we can start
making changes.
For example, in case of an Astro project, you get a `watching for file
changes` message. In case of Nuxt project you can wait for an `server
warmed up in` and in case of Next.js there is a `Ready in` message.
These depend on the tools being used, so this is hardcoded per test
instead of a magically automatic solution.
These messages allow us to wait until all the initial necessary work,
internal watchers and/or dev servers are setup before we start making
changes to the files and/or request CSS stylesheets before the server(s)
are ready.
---
Another improvement is how we setup the dev servers. Before, we used to
try and get a free port on the system and use a `--port` flag or a
`PORT` environment variable. Instead of doing this (which is slow), we
rely on the process itself to show a URL with a port. Basically all
tools will try to find a free port if the default port is in use. We can
then use the stdout/stderr messages to get the URL and the port to use.
To reduce the amount of potential conflicts in ports, we used to run
every test and every file sequentially to basically guarantee that ports
are free. With this new approach where we rely on the process, I noticed
that we don't really run into this issue again (I reran the tests
multiple times and they were always stable)
<img width="316" alt="image"
src="https://github.com/user-attachments/assets/b75ddab4-f919-4995-85d0-f212b603e5c2"
/>
Note: these tests run Linux, Windows and macOS in this branch just for
testing purposes. Once this is done, we will only run Linux tests on PRs
and run all 3 of them on the `next` branch.
We do make the tests concurrent by default now, which in theory means
that there could be conflicts (which in practice means that the process
has to do a few more tries to find a free port). To reduce these
conflicts, we split up the integration tests such that Vite, PostCSS,
CLI, … tests all run in a separate job in the GitHub actions workflow.
<img width="312" alt="image"
src="https://github.com/user-attachments/assets/fe9a58a1-98eb-4d9b-8845-a7c8a7af5766"
/>
Comparing this branch against the `next` branch, this is what CI looks
like right now:
| `next` | `feat/improve-integration-tests` |
| --- | --- |
| <img width="594" alt="image"
src="https://github.com/user-attachments/assets/540d21eb-ab03-42e8-9f6f-b3a071fc7635"
/> | <img width="672" alt="image"
src="https://github.com/user-attachments/assets/8ef2e891-08a1-464b-9954-4153174ebce7"
/> |
There also was a point in time where I introduced sequential tests such
that all spawned processes still run after each other, but so far I
didn't run into issues if we keep them concurrent so I dropped that
code.
Some small changes I made to make things more reliable:
1. When relying on stdout/stderr messages, we split lines on `\n` and we
strip all the ANSI escapes which allows us to not worry about special
ANSI characters when finding the URL or a specific message to wait for.
2. Once a test is done, we `child.kill()` the spawned process. If that
doesn't work, for whatever reason, we run a `child.kill('SIGKILL')` to
force kill the process. This could technically lead to some memory or
files not being cleaned up properly, but once CI is done, everything is
thrown away anyway.
3. As you can see in the screenshots, I used some nicer names for the
workflows.
| `next` | `feat/improve-integration-tests` |
| --- | --- |
| <img width="276" alt="image"
src="https://github.com/user-attachments/assets/e574bb53-e21b-4619-9cdb-515431b255b9"
/> | <img width="179" alt="image"
src="https://github.com/user-attachments/assets/8bc75119-fb91-4500-a1d0-bd09f74c93ad"
/> |
They also look a bit nicer in the PR overview as well:
<img width="929" alt="image"
src="https://github.com/user-attachments/assets/04fc71fc-74b0-4e7c-9047-2aada664efef"
/>
The very last commit just filters out Windows and macOS tests again for
PRs (but they are executed on the `next` branch.
---
### Nest steps
I think for now we are in a pretty good state, but there are some things
we can do to further improve everything (mainly make things faster) but
aren't necessary. I also ran into issue while trying it so there is more
work to do.
1. More splits — instead of having a Vite folder and PostCSS folder, we
can go a step further and have folders for Next.js, Astro, Nuxt, Remix,
…
2. Caching — right now we have to run the build step for every OS on
every "job". We can re-use the work here by introducing a setup job that
the other jobs rely on. @thecrypticace and I tried it already, but were
running into some Bun specific Standalone CLI issues when doing that.
3. Remote caching — we could re-enable remote caching such that the
`build` step can be full turbo (e.g.: after a PR is merged in `next` and
we run everything again)
There are still instances in which CI is flaky after #14332. This PR
applies the same fix (that is, moving the file write into the retrying
block) to all `retryAssertion` callbacks.
This PR fixes an issue introduced with the changed candidate cache
behavior in #14187.
Prior to #14187, candidates were cached globally within an instance of
Oxide. This meant that once a candidate was discovered, it would not
reset until you either manually cleared the cache or restarted the Oxide
process. With the changes in #14187 however, the cache was scoped to the
instance of the `Scanner` class with the intention of making the caching
behavior more easy to understand and to avoid a global cache.
This, however, had an unforeseen side-effect in our Vite extension.
Vite, in dev mode, discovers files _lazily_. So when a developer goes to
`/index.html` the first time, we will scan the `/index.html` file for
Tailwind candidates and then build a CSS file with those candidate. When
they go to `/about.html` later, we will _append_ the candidates from the
new file and so forth.
The problem now arises when the dev server detects changes to the input
CSS file. This requires us to do a re-scan of that CSS file which, after
#14187, caused the candidate cache to be gone. This is usually fine
since we would just scan files again for the changed candidate list but
in the Vite case we would only get the input CSS file change _but no
subsequent change events for all other files, including those currently
rendered in the browser_). This caused updates to the CSS file to remove
all candidates from the CSS file again.
Ideally, we can separate between two concepts: The candidate cache and
the CSS input file scan. An instance of the `Scanner` could re-parse the
input CSS file without having to throw away previous candidates. This,
however, would have another issue with the current Vite extension where
we do not properly retain instances of the `Scanner` class anyways. To
properly improve the cache behavior, we will have to fix the Vite
`Scanner` retaining behavior first. Unfortunately this means that for
the short term, we have to add some manual bookkeeping to the Vite
client and retain the candidate cache between builds ourselves.
---------
Co-authored-by: Jordan Pittman <jordan@cryptica.me>
Using the [new integration test
setup](https://github.com/tailwindlabs/tailwindcss/pull/14089), this PR
adds a test for a V4 Next.js setup using the Postcss plugin. It's
testing both a full build and the dev mode (non-turbo for now).
Because of webpack, tests are quite slow which is worrisome since we
probably need to add many more integrations in the future. One idea I
have is that we separate tests in two buckets: _essential_ tests that
run often and are fast and advanced suites that we only run on CI via
custom, non-blocking, jobs.
---------
Co-authored-by: Jordan Pittman <jordan@cryptica.me>
