VS Code: Task to run Elixir tests

tasks.json

{
  "version": "2.0.0",
  "tasks": [{
      "group": {
        "kind": "test",
        "isDefault": true
      },
      "label": "elixir: run stale tests",
      "type": "shell",
      "command": "mix test --stale",
      "problemMatcher": [],
      "presentation": {
        "clear": true
      }
    }, {
      "group": "test",
      "label": "elixir: run all tests",
      "type": "shell",
      "command": "mix test",
      "problemMatcher": [],
      "presentation": {
        "clear": true
      }
    },
    {
      "group": "test",
      "label": "elixir: run test at cursor",
      "type": "shell",
      "command": "mix test --only line:${lineNumber} ${relativeFile}",
      "problemMatcher": [],
      "presentation": {
        "clear": true
      }
    }
  ],
}