Support Workspace Launch Configuration

[RomanNikitenko]

Feature Description:

VS Code supports adding launch configurations to the workspace configuration file.

Please see more details here: https://code.visualstudio.com/docs/editor/multi-root-workspaces#_workspace-launch-configurations

[RomanNikitenko]

Theia supports Workspace Launch configurations.

The configurations should be defined in workspace config file like:

"settings": {
        "launch": {
            "configurations": [
                {
                    "name": "Launch Chrome",
                    "request": "launch",
                    "type": "pwa-chrome",
                    "url": "http://localhost:8080",
                    "webRoot": "${workspaceFolder}"
                }
            ]
        }
    },

At creating the issue I tested another format described in the docs of VS Code: https://code.visualstudio.com/docs/editor/multi-root-workspaces#_workspace-launch-configurations, so like:

"launch": {
    "configurations": [
      {
        "name": "Launch Chrome",
        "request": "launch",
        "type": "pwa-chrome",
        "url": "http://localhost:8080",
        "webRoot": "${workspaceFolder}"
      }
    ],
    "compounds": []
  },

Please pay attention that for the first case the configuration is placed within settings object. The second way (launch field is outside settings) doesn't work for Theia at the moment.

VS Code supports both formats: configs inside and outside settings. But configurations outside settings obscure configs insidesettings - so user should use only one way - either ... either. Please see https://github.com/eclipse-theia/theia/pull/8917#issuecomment-764709137

[colin-grant-work]

A few more details: There are two kinds of clobbering going on.

• In a workspace file, launch outside of the settings object overrides launch inside the settings object (or they will once #8917 is merged). This is consistent with VSCode behavior.
• In a multi-root workspace, if a particular folder has no launch.json then any configurations present in the workspace file will be listed (e.g. in the DebugConfigurationWidget) for that folder as well. If you add a launch.json to that folder, then workspace-scoped debug configurations will no longer be listed for that folder. In VSCode, in the analog of the DebugConfigurationWidget, workspace-scoped debug configurations are always listed separately and never listed as associated with a particular folder.

That means that there are two bugs in the current code:

1. Workspace-scoped configurations are being associated with folders
2. Workspace-scoped configurations are not being listed separately.

The cause of the first bug is a peculiarity of the way DebugConfigurationManager.parseConfigurations gets data from PreferenceService.resolve:

https://github.com/eclipse-theia/theia/blob/42042974c59f148974de5e8fd90cba7222cee82f/packages/core/src/browser/preferences/preference-service.ts#L495-L513

Since .resolve loops through all scopes and retrieves data, merging the data as it goes, if it picks up a value for launch from workspace scope and not one from the folder, then it will keep the workspace-scoped value, and the DebugConfigurationModel for the folder will report it as though the data belonged to it.

The cause of the second bug is that in the DebugConfigurationManager there is no DebugConfigurationModel associated with workspace scope.

[RomanNikitenko]

@colin-grant-work thanks for your investigation and provided details!

Yesterday I created one more issue related to launch configurations: https://github.com/eclipse-theia/theia/issues/8985 I created it as enhancement, I thought the current behavior is the result of the first implementation of launch configs in Theia without alignment of the behavior with VS Code.
But now for me it looks like a bug and your investigation contains some details related to the cause of the problem.