add watch option

[derberg]

Reason/Context

We need native way for watching AsyncAPI resource and reiterate given command on it. So basically asyncapi validate -w works in a way that whenever users introduce change in a file, validation runs on it again without invoking it.

sure user can now just install watcher like brew install watch and do watch asyncapi validate, but this should be considered as a temporary workaround that is not a good UX.

Description

When working on this functionality we need to look on current functionality on Generator CLI and its current issues, to fix them here in the CLI -> asyncapi/generator#537 (comment)

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[imabp]

We need native way for watching AsyncAPI resource...

@derberg Do you mean Native as the NodeJS Runtime or based on operating system?

• If NodeJS Runtime, an oclif hook is required to watch over the file and run the command using nodejs built in module fs. here

Would like to take up this issue :)

[imabp]

A question @derberg
Do we need watch option as a global flag, or specific to validate ?

[derberg]

best would be if it is global but that you need to enable it for given command 😄

so validate, diff, should have it, but new, start not really. So would be awesome to have it generic in a sense that when we add new generate command, we easily enable watch for it

[derberg]

we already do some watching here

cli/src/models/Studio.ts

Line 17 in 058114c

chokidar.watch(filePath).on('all', (event, path) => {

.

so it is a matter of making a global function that can be reused by a command that needs it

[imabp]

That means the flow goes like this 👇

1. Create a global function for watch using chokidar
2. Conditional check --watch flag
3. If conditional check is true run the global function.

Correct me, if somewhere missing any point

[imabp]

@derberg please review, #220
Relax and watch specification files 🍻

[imabp]

@derberg The watcher PR is ready to review: #220

I got a bit in stuck moment when writing test for --watch flag using Mocha, @fmvilas because

• Mocha is unable to close the stream once the test is completed, (as watch mode works in stream), hence npm run test runs for indefinite period of time.

Need some solutions on how do we approach it? Mocking Streams or any other way ?

[derberg]

tbh I'm not sure, I would first try to check if chokidar community figured it out already, maybe something is already in their issues, or you can check others that use chokidar and how they solved testing. I would go first this direction to see how others tacked it

[imabp]

@derberg, we can close this issue, as #220 is merged :)

[derberg]

@imabp well done 👏🏼