tasks.json

{
  "version": "0.1.0",
  "command": "${workspaceRoot}/node_modules/.bin/mocha",
  "isShellCommand": false,
  "showOutput": "never",
  "args": [],
  "tasks": [
    {
      "taskName": "test",
      "suppressTaskName": true,
      "args": [
        "test/unit",
        "--recursive"
      ],
      "isTestCommand": true,
      "showOutput": "silent",
      "isWatching": false,
      "problemMatcher": {
        "owner": "mocha",
        "fileLocation": [
          "absolute"
        ],
        "pattern": [
          {
            "regexp": "^\\s*\\d+\\)\\s+(.+):$",
            "message": 1
          },
          {
            "regexp": "^\\s+.*$"
          },
          {
            "regexp": "^\\s+.*$"
          },
          {
            "regexp": "^\\s+.*$"
          },
          {
            "regexp": "^\\s+.*$"
          },
          {
            "regexp": "^\\s+.*$"
          },
          {
            "regexp": "\\s+at\\s(.*)\\s\\((.*?:.*?):(\\d+):(\\d+)\\)",
            "file": 2,
            "line": 3,
            "column": 4
          }
        ]
      }
    }
  ]
}

add to .vscode/ folder in project root