[
  {
    "id": "$lookup example",
    "stage": "$lookup",
    "kind": "example",
    "pipeline": [
      {
        "$lookup": {
          "from": [
            {
              "sku": "P1",
              "price": 5
            }
          ],
          "localField": "sku",
          "foreignField": "sku",
          "as": "products"
        }
      }
    ],
    "input": [
      {
        "sku": "P1"
      },
      {
        "sku": "P2"
      }
    ],
    "result": [
      {
        "sku": "P1",
        "products": [
          {
            "sku": "P1",
            "price": 5
          }
        ]
      },
      {
        "sku": "P2",
        "products": []
      }
    ]
  },
  {
    "id": "$lookup empty input",
    "stage": "$lookup",
    "kind": "empty input",
    "pipeline": [
      {
        "$lookup": {
          "from": [
            {
              "sku": "P1",
              "price": 5
            }
          ],
          "localField": "sku",
          "foreignField": "sku",
          "as": "products"
        }
      }
    ],
    "input": [],
    "result": []
  },
  {
    "id": "$lookup invalid specification",
    "stage": "$lookup",
    "kind": "invalid specification",
    "pipeline": [
      {
        "$lookup": null
      }
    ],
    "input": [
      {
        "sku": "P1"
      },
      {
        "sku": "P2"
      }
    ],
    "error": "IllegalArgumentException",
    "message": "$lookup stage expects an object specification"
  },
  {
    "id": "$lookup missing named dataset",
    "stage": "$lookup",
    "kind": "missing named dataset",
    "pipeline": [
      {
        "$lookup": {
          "from": "products",
          "localField": "sku",
          "foreignField": "sku",
          "as": "products"
        }
      }
    ],
    "input": [
      {
        "sku": "P1"
      }
    ],
    "error": "IllegalArgumentException",
    "message": "foreign collection 'products' not available"
  }
]