All CLA requirements met.

Thanks for the pr, however this week we are wrapping up our milestone which means I will review this PR start of next week.

@dbaeumer fyi

Looking at the original issue I am not so convinced this is needed in our core. What is the big use case scenario that could profit from this PR?
Since none of the debug users asked for this afaik I am assigning to @dbaeumer so he can decide if this is good to have or not wrt to the tasks.json.

@yitongding I agree with @isidorn. Can you please outline in which cases a selected text is needed for tasks ?

@dbaeumer @isidorn Hi, thanks for reviewing!

Here is my use case for selected text:

As a frontend developer, I use a e2e test framework called nightwatch. When running the test, there is an option to choose which test case in the current test file I would like to run. So the command will be like nightwatch --test header.js --testcase 'should render'.

Currently, I use task.json to run the test with arg: ['--test', '${file}']. However, this will run the whole test file, and sometimes it could takes very long time before the test case I really care gets to run. With arg: ['--test', '${file}', '--testcase', '${selectedText}'], I'll be able to run the target text case only by selecting the test case title.

Hopefully, I made my self clear 😄

@yitongding thanks for the example. This makes sense to me.

@dbaeumer, actually, I see almost the the same case with running Karma tests in our project, that's why I voted for this issue.

@isidorn any comments on the code. It looks good to me.

@dbaeumer I will review a bit lataer today and if it looks good I will merge it in. Thanks

@yitongding I just reviewed the code and it looks good to me. Thanks a lot
@yitongding if you would also like to provide a pr to our vscode-docs that would also be really appreciated. If not @dbaeumer and me will cover this in our release notes and documentation in endgame week.

@isidorn Thanks for reviewing!
I've made a pr to microsoft/vscode-docs#1317

@yitongding @isidorn I'm having trouble getting this to work on 1.20 Insiders. Here's my tasks.json:

{
    "version": "2.0.0",
    "tasks": [
        {
            "label": "echo",
            "type": "shell",
            "command": "echo",
            "args": [
                "${selectedText}"
            ]
        }
    ]
}

I just see "Executing task: echo ${selectedText}". If I use "${file}" or "${lineNumber}" it works fine.

@gregvanl we have frozen insiders during the holidays - so no new updates are coming. So once we update the insiders start of january this should work just fine :)

It seems that ${selectedText} variable is not added yet. Anyone know in which release this will be added ? I need this for one of the task :(

Sorry this feature is already added in latest release but documentation is missing .

@nileshkhaire we accept PRs that fix this. Here's our repo https://github.com/microsoft/vscode-docs
fyi @gregvanl

Request:
${selectedText} gets truncated to the first line, please consider including a multi-line selection when populating the variable.
Example use:

"JS Block Quote": {
	"prefix": "c2",
	"body": [
		"/* ${selectedText} */",
	],
	"description": "JS Block Quote"
}

Thanks.