resolving multiple tasks with type npm and same script fails

[Strandinator]

Issue Type: Bug

Create 2 tasks with "type": "npm" and same "script"

Expected both tasks to be resolved by their label

• VsCode will list only one of those tasks when listing available tasks with "Tasks: Run Task".
• Depending tasks will fail with "Couldn't resolve dependent task 'x' in workspace folder 'y'" in the "Tasks" output.

tasks.json:

{
    "version": "2.0.0",
    "tasks": [
        {
            "label": "start_both",
            "type": "shell",
            "dependsOn": [
                "start_nr_1",
                "start_nr_2"
            ],
            "problemMatcher": []
        },
        {
            "label": "start_nr_1",
            "type": "npm",
            "script": "start",
            "problemMatcher": []
        },
        {
            "label": "start_nr_2",
            "type": "npm",
            "script": "start",
            "options": {
                "env": {
                    "SOME": "option"
                }
            },
            "problemMatcher": []
        },
    ]
}

package.json:

{
  "scripts": {
    "start": "echo running 'start' script"
  }
}

VS Code version: Code 1.43.1 (fe22a96, 2020-03-18T07:01:20.184Z)
OS version: Windows_NT x64 10.0.19041

System Info

Item	Value
CPUs	Intel(R) Core(TM) i7-4790 CPU @ 3.60GHz (8 x 3592)
GPU Status	2d_canvas: enabled flash_3d: enabled flash_stage3d: enabled flash_stage3d_baseline: enabled gpu_compositing: enabled multiple_raster_threads: enabled_on oop_rasterization: disabled_off protected_video_decode: unavailable_off rasterization: enabled skia_renderer: disabled_off_ok video_decode: enabled viz_display_compositor: enabled_on viz_hit_test_surface_layer: disabled_off_ok webgl: enabled webgl2: enabled
Load (avg)	undefined
Memory (System)	15.92GB (8.47GB free)
Process Argv
Screen Reader	no
VM	0%

Extensions: none

[vscodebot]

(Experimental duplicate detection)
Thanks for submitting this issue. Please also check if it is already covered by an existing one, like:

• Change debugging tab to be tasks tab (#38969)
• Provide Task Runner viewlet (#28235)
• NPM scripts in different folders with same name not working (#92508)
• Keyboard shortcut for named global task shows selection (#90344)
• Cannot specify global problemMatcher in tasks.json (#81237)

[Strandinator]

Workaround would be to simply define a separate script in package.json for each task

[alexr00]

This is by design. An extension provided task, such as a task of "type": "npm" is identified by it task-type-specific properties (for npm tasks, this is script). Tasks are not identified by label, a label is just a nice human readable string.

Since this is very easily worked around by having a separate npm script in your package.json I wouldn't make any changes in the behavior. However, it is not nice that the first time you learn that you can't have two of the same task is when you try to run a task that depends on it. I will add an error earlier, so that it's clear what's happening when the task list shows.

[GordonSmith]

@alexr00 I just hit this today as well, in my situation both script calls had different working directories:

		{
			"label": "server tsc watch",
			"type": "npm",
			"script": "compile-watch",
			"options": {
				"cwd": "web/server"
			},
			"problemMatcher": [
				"$tsc-watch"
			],
			"presentation": {
				"group": "group-build"
			}
		},
		{
			"label": "client tsc watch",
			"type": "npm",
			"script": "compile-watch",
			"options": {
				"cwd": "web/client"
			},
			"problemMatcher": [
				"$tsc-watch"
			],
			"presentation": {
				"group": "group-build"
			}
		},

In my case I don't really have ownership of the web/client and web/server package.json files, so renaming or adding script sections is not an option...

[nelisbijl]

Workaround: add a path property and use '.', or './.' or '././.' etc.

[joyceerhl]

@alexr00 would it be possible to include the options (particularly cwd) in the unique identification of a task? I just ran into this while trying to configure build tasks in an npm workspace where the sub-workspaces had identically named scripts with different cwds. As you note, it's easy to work around this, but it was definitely surprising behavior and I wasted time trying to figure out what I'd misconfigured.

[alexr00]

It's not possible with the way that the tasks system is currently implemented. The npm extension already provides a way to do this without renaming scrips using the path property too.

[clshortfuse]

My workaround is to just add spaces to the script name:

script": "debug" => script": "debug " => script": " debug "

Also, on @alexr00 point:

Tasks are not identified by label, a label is just a nice human readable string.

That's not entirely true. launch.json specifically picks tasks by label. This is how I found this issue in the first place. preLaunchTask expects a label. So it's strange launch.json can "see" labels, but tasks.json can't.

I also don't think this is a "polish" issue. Having to add spaces is a sloppy workaround, and it's confusing trying to integrate launch.json, where when it's clearly defined in tasks.json, but refuses to work.

[clshortfuse]

After a lot of digging, it seems npm tasks aren't considered CustomTask objects, so it uses the TaskRegistry to build the identifier. If it was a CustomTask, then it works by label.

vscode/src/vs/workbench/contrib/tasks/common/taskConfiguration.ts

Line 1409 in 4a130c4

identifier = { type: 'npm', script: customize.substring(npm.length + 4) };

Basically, it creates an identifier, and then a keyed one based on its properties:

vscode/src/vs/workbench/contrib/tasks/common/taskConfiguration.ts

Line 1425 in fb4c12b

let taskIdentifier: Tasks.KeyedTaskIdentifier | undefined = Tasks.TaskDefinition.createTaskIdentifier(identifier, context.problemReporter);

Since the fields passed aren't unique enough, the key is duplicated and only the last entry will persist when it eventually moves to a Map. One solution is to move to entry tuples (eg: [key, value][]), or increase uniqueness by uses more fields in the npm identifier. I think just including options property is enough.

It also seems this bug isn't just npm, but grunt, jake, gulp, and typescript as well.

Edit: Oh, I think I'm wrong about some of that. Basically, createTaskIdentifier will build a unique key around required parameters. Because options isn't required, it won't be included when creating a unique identifier.

[clshortfuse]

Workaround of using spaces no longer works as of v1.66.2 :(

[jakebailey]

I just hit this in the TS repo, where I'm changing our build but leaving some tasks behind for backwards compat. I had:

        {
            "label": "npm: build:tests",
            "type": "npm",
            "script": "build:tests",
            "group": "build",
            "problemMatcher": [
                "$tsc"
            ]
        },
        {
            "label": "gulp: tests",
            "type": "npm",
            "script": "build:tests",
            "group": "build",
            "hide": true,
            "problemMatcher": [
                "$tsc"
            ]
        },

We don't commit launch.json, but we do commit tasks.json, so I was leaving an old task behind as to not cause breakage for the people on my team with old launch configs. But, when I opened the task menu, I only saw the latter open.

The "fix" for me was to move the deprecated gulp task to the top (with a big explanatory comment), as the last use of a script is the one that appears to win. Obviously, this only works because I am content with just one of the scripts showing up, and we don't set cwd or anything.

[starball5]

Related on Stack Overflow: Why does only the last NPM task in VS Code of several that only vary by label and options (and not the script) get picked up?

[golf1052]

@alexr00 @meganrogge If an external contributor wanted to try and fix this what would be the next steps?