test: industrialize tests with snapshots

[yacinehmito]

This PR adds the ability to test bundle and emit with snapshots. Instead of writing assertions on the output, it will be automatically compared with files already stored.

Why I did this

I would like to start fixing a few bugs (starting with #98), then contribute with my own improvements. Having snapshots makes me more confident that I will not cause a regression, and will let me see clearly the difference between the output of my revisions vs. the original output.

Why I did not use assertSnapshot from the standard library

There are already ways of doing snapshot testing from what std provides. However, with the existing assertSnapshot, the snapshot files are big and hard to read. The functions of deno_emit produce JavaScript code, so I preferred to store the snapshots as JavaScript files. With the absence of escape characters and the help of syntax highlighting, we can better appreciate the changes.

Other changes

The existing tests have been converted to using snapshots. Tests of bundle and tests of emit have been separated in two different files.

[CLAassistant]

All committers have signed the CLA.

[dsherret]

LGTM. Thanks a lot!

[dsherret]

@yacinehmito seems some tests are failing.

[yacinehmito]

I think it's because the source maps depend on something device-specific (probably the full path). I'll dig further.

[yacinehmito]

@dsherret Tests are fixed.

[yacinehmito]

I added functions to "fix" the source maps, so that they use relative paths instead of absolute paths.
This is a bit hacky; I would have preferred to do this Rust-side, but the logic is deep in deno_ast so that wasn't a practical option.

[yacinehmito]

@dsherret Sorry for pinging you again.

[dsherret]

@yacinehmito the CI is still failing. I fixed the one newline issue.

[yacinehmito]

I didn't realize that there was a windows run. I am not surprised if it fails because of line endings given how I split the lines in the testing code. It's a bit hard to test on my end as I cannot trigger the CI.

I'll push a fix early next week (I am off until then).

[dsherret]

I can try to fix it in a bit (maybe later tonight or tomorrow). Yeah, the CI doesn't run automatically because this is your first PR to this repo. I wish it would after the first time I approve it.

[yacinehmito]

I have added this bit and used it everywhere instead of \n. @dsherret Does that make the tests pass now?

[dsherret]

I had fixed that issue by adding a .gitattributes to this PR, which is preferable because then we don't need these kind of conditions. The tests were complaining about this:

,-     "file:///D:/a/deno_emit/deno_emit/testdata/mod.ts": "cYfK3r_ND0Q_nXVQYOxJjg8VYMM.js"\n
,+     "file:///testdata/mod.ts": "0BJ1Cp_wwHSv6YnJzSlY2UlxpSc.js"\n

Previous run: https://github.com/denoland/deno_emit/actions/runs/4726314879/jobs/8385766439

Now the tests are failing with more newline stuff. Can you revert your last change (I have the old code locally in case you've lost it so just let me know if you want me to push it to this PR)? Also, please land commits on top of each other instead of overwritting commits because I don't know what has changed since the last time I reviewed. We'll squash all the commits when merging.

[yacinehmito]

I reverted the changes. I also found how to run the Actions on my own fork, so I can iterate on the Windows issue.

(FYI, the Windows build takes a lot of time. Compiling Rust dependencies takes more than 12 minutes, whereas it takes less than 5 minutes for Linux and less than 2 minutes for macOS.)

[yacinehmito]

We're almost there. There's only one test failing, because of line endings.

[yacinehmito]

@dsherret It's finally green on my fork! 😄

[yacinehmito]

I removed the queue to update the snapshots so that I could forward the paths to the module outputs to the more function, which can be used to perform more assertions.

I did that because I am porting the tests from deno bundle in here, and some of them need to execute the bundled code. I figured that I could directly get it from the snapshot instead of bundling another time in a temporary directory.