feat: support unwatchFile

[aleung]

• implement unwatchFile
• add unit test case for it
• format the code with prettier

[tstordyallison]

+1 for this if anyone is around to review...

I stumbled across the error and it led me here!

[G-Rath]

@aleung it looks like your test might be a bit unstable - would you be willing to look into that for us?

[aleung]

@G-Rath The test failed in "union › Union › Streams › can create Writable Streams" but I didn't change this one. The test added in my PR is "union › Union › sync methods › watch() › can watchFile and unwatchFile". Anyway, I'll try to run test locally to verify it.

[G-Rath]

@aleung yeah that failure is a different one. The failure from this PR seems to only happen when you run the tests multiple times (so won't show up in CI) due to files being created so it looks like it behaves differently on subsequent runs.

Thanks for looking into this! I'm a bit slammed at the moment so any time you can spare is appreciated 😊

[G-Rath]

@aleung it looks like the issue was just timing - adding another call to sleep between setting up the watcher and the initial writing to file looks to have resolved the issue.

[aleung]

@G-Rath Great. Do you need any more action from me?

[G-Rath]

@aleung at the time no, but now it looks like after a general lockfile update (#758) a new issue has start occuring:

● union › Union › sync methods › watch() › should create a watcher

    expect(jest.fn()).toBeCalledWith(...expected)

    Expected: "change", "/tmp/foo.js"
    Received
           1: "change", ""
           2: "change", ""

    Number of calls: 2

       95 |
       96 |           ufs.use(fs).use(Volume.fromJSON({ 'foo.js': '' }, '/tmp') as any);
    >  97 |
          | ^
       98 |           expect(ufs.existsSync(__filename)).toBe(true);
       99 |           expect(fs.existsSync(__filename)).toBe(true);
      100 |           expect(ufs.existsSync('/tmp/foo.js')).toBe(true);

      at Object.<anonymous> (src/__tests__/union.test.ts:97:42)

[G-Rath]

It looks like the issue is because of streamich/memfs#902

[G-Rath]

This has now been released in 4.5.0 🎉