Theia: [Question] How to debug Theia plugin folder

[kvbhat]

Hi All,
I would like to contribute and work on plugin-system of theia.

But I'm unable to make the debug setup for the same.

I have followed these setups to debug the ~/theia/packages/plugin-ext/src/plugin/languages/hover.ts file-

1) Build Theia on VSCode.
2) From Debug "Launch Backend" Configuration.
3) From Debug "Launch Frontend" Configuration.
4) Create a plugin in the launched instance (hello world using the guide from https://www.theia-ide.org/doc/authoring_plugins ) and updated it to use the below code-

import * as theia from '@theia/plugin';

export function start() {
    theia.languages.registerHoverProvider({scheme: 'file'}, {
    provideHover(doc: theia.TextDocument, position: theia.Position) {
        const range = doc.getWordRangeAtPosition(position);
        const text = doc.getText(range);
        return new theia.Hover(text);
    }
    });
}

export function stop() {

}

so that hover.ts source code is called.

5) Run command "Hosted mode: start instance"

After this step i get the below error-

yarn run v1.7.0
$ /home/kvbhat/git/IDE/theia/node_modules/.bin/theia start --port=3030
module.js:549
    throw err;
    ^
Error: Cannot find module '/home/kvbhat/git/IDE/theia/src-gen/backend/main.js'
    at Function.Module._resolveFilename (module.js:547:15)
    at Function.Module._load (module.js:474:25)
    at Function.Module.runMain (module.js:693:10)
    at startup (bootstrap_node.js:191:16)
    at bootstrap_node.js:612:3
Done in 0.47s.

Could someone please guide me on how to debug the plugin-system that are being develop for theia?

Update:
If i launch backend via command line and just launch fronted i dont get the above error but then breakpoints in hover.ts are not getting hit even though the hover plugin is activated and called.

Thanks

[elaihau]

i tried the "hosted plugin: debug instance" command, which asks me for the path of the plugin (in my local environment it is theia/plugins/the-plugin-to-debug). And, the command populates a dialog that helps me to open another instance of theia.

however, my break points are not hit either. I tried dropping break point in both theia instances (i.e., the one running on port 3000, and the one on 3030), and neither worked. Could you @benoitf please point us to the wiki that explains how debugging

• theia plugins, and
• vsCode extensions as theia plugins
  should work ?

Thank you !

[benoitf]

@elaihau you're using master branch and examples/browser or a different config ?

[elaihau]

yes i am on the master branch, using examples/browser

[benoitf]

@elaihau I made this quick video https://www.youtube.com/watch?v=Kjwovxq38Ms&feature=youtu.be

was trying against a Theia plug-in.

[elaihau]

Thank you @benoitf !
Following your video I made a GIF to show how to debug a vscode extension as a theia plugin.

[akosyakov]

You can create a node debug launch configuration: https://github.com/theia-ide/theia/issues/4224#issuecomment-459752557

In order to debug just press F5:

Example of debug configuration:

        {
            "name": "Launch VS Code extension",
            "type": "node",
            "request": "launch",
            "port": 9339,
            "timeout": 100000,
            "args": [
                "${workspaceFolder}/examples/browser/src-gen/backend/main.js",
                "${workspaceFolder}",
                "--port=3030",
                "--hosted-plugin-inspect=9339",
                "--plugins=local-dir:${workspaceFolder}/plugins"
            ],
            "stopOnEntry": false,
            "sourceMaps": true,
            "outFiles": [
                "${workspaceFolder}/**/*.js"
            ],
            "internalConsoleOptions": "openOnSessionStart",
            "outputCapture": "std"
        }