mb-graphql

Welcome, friend

mb-graphql is a mountebank plugin that makes creating test doubles for GraphQL APIs a lot simpler... and fun: there's no code to write.

Wraps Apollo Server to allow easy declaration of a mock GraphQL server via mountebank stubs (see below).

Features

• No code to write: Use mountebank's REST API to create test doubles
• Create mock GraphQL APIs based on in-line or remote schema definitions
• Run as a proxy to an existing GraphQL API
• Record requests made against mocked GraphQL API (useful for Golden Master Testing)

Getting started

Option 1: Run with Docker (the easiest option)

docker run -p 2525:2525 [-p IMPOSTER_PORT:IMPOSTER_PORT] -d bashj79/mountebank-graphql

NOTE: mountebank itself runs on port 2525.

Check out Docker Hub for further details.

Option 2: Install and Run

Prerequisite:

• mountebank

npm install -g mb-graphql

Start mountebank with the following protocols.json file (master on GitHub):

{
  "graphql": {
    "createCommand": "mb-graphql"
  }
}

mb start --protofile protocols.json

Example

imposter.json

{
  "port": 4000,
  "protocol": "graphql",
  "schema": "type Thing { alpha: Int beta: String } type Query { myQuery(myFirstArg: Int, mySecondArg: Int): Thing }",
  "stubs": [
    {
      "predicates": [
        {
          "equals": {
            "query": "myQuery",
            "args": {
              "myFirstArg": 123
            }
          }
        }
      ],
      "responses": [
        {
          "is": {
            "data": {
              "beta": "abcdef"
            }
          }
        }
      ]
    }
  ]
}

Create the imposter via mountebank (assuming it's running on localhost:2525):

curl -i -X POST -H 'Content-Type: application/json' http://localhost:2525/imposters --data @imposter.json

You can now access the GraphQL playground for the imposter at http://localhost:4000:

Request

query {
    myQuery(myFirstArg: 123, mySecondArg: 456) {
        alpha
        beta
    }
}

Response

{
  "data": {
    "myQuery": {
      "alpha": 42,
      "beta": "abcdef"
    }
  }
}

Note: The value for myQuery.alpha has been randomly generated as it was omitted from the stub's response.

For further examples please check out the features folder.

Imposter Creation Parameters

For further information about mountebank imposters, stubs and related concepts please refer to the mountbank mental model.

Parameter	Description	Required?	Default
protocol	Must be set to graphql	Yes	N/A
port	The port to run the imposter on.	No	A randomly assigned port. mountebank will return the actual value in the POST response.
name	Included in the logs, useful when multiple imposters are set up.	No	An empty string.
schema	A string presenting a valid GraphQL schema definition.	No, if schemaEndpoint is set	N/A
schemaEndpoint	URL of a GraphQL schema file or the endpoint of an existing GraphQL API which exposes the GraphQL introspection query.	No, if schema is set	N/A
schemaEndpointHeaders	An object representing headers to passed to the schema endpoint defined in schemaEndpoint e.g. Authorization header.	No	An empty object.
stubs	The list of stubs responsible for matching a GraphQL request and returning a response. See further details below.	No	An empty array.
defaultResponse	The default response for any top-level query/mutation performed against the schema.	No	Default behaviour for the imposter is to return random data according to the defined schema.

GraphQL Request Predicates

Field	Description	Type
query	The name of the GraphQL query e.g. myQuery.	String
mutation	The name of the GraphQL mutation e.g. myMutation.	String
args	The arguments passed to the GraphQL query/mutation.	Object
headers	The HTTP headers passed to the GraphQL query/mutation.	Object

Please see the mountebank predicate documentation for further details of mountebank's stub predicates and their usage.