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scenario-mock-server
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1.2.0 • Public • Published

Scenario Mock Server

Mock server powered by scenarios.

Table of contents

Installation

npm install scenario-mock-server

Example usage

const { run } = require('scenario-mock-server');

run({
	scenarios: {
		item: [
			{
				path: '/api/test-me',
				method: 'GET',
				response: { data: { blue: 'yoyo' } },
			},
		],
		cheese: [
			{
				path: '/api/test-me',
				method: 'GET',
				response: { data: { blue: 'cheese' } },
			},
		],
	},
});

Calls to http://localhost:3000/api/test-me will start by returning { blue: 'yoyo' }.

Visiting http://localhost:3000 will allow you to select a scenario. The first declared scenario will be initially selected. In this case, enabling cheese will modify /api/test-me so that it returns { blue: 'cheese' }.

Cookie mode

By default Scenario Mock Server runs in server mode storing the current selected scenario and context in server memory. Alternatively you can set cookieMode to true in the options, which stores the current scenario and context in a cookie instead. This is useful when you want to run a central mock server, but allow each user to select and store their own scenarios and associated contexts without it affecting other users.

Allowing for multiple responses

Sometimes you may want an endpoint to respond with different status codes depending on what is sent. It is the recommendation of this package that this can be achieved by using scenarios. However, given response can be a function, it is possible to respond with a different value for the status, headers, data and delay properties:

const mock = {
	path: '/some-path',
	method: 'GET',
	response: ({ body }) => {
		if (body.name === 'error1') {
			return {
				status: 400,
				data: { message: 'something went wrong' },
				delay: 1000,
			};
		}

		if (body.name === 'error2') {
			return {
				status: 500,
				data: { message: 'something else went wrong' },
				delay: 2000,
			};
		}

		if (body.name === 'notFound') {
			return {
				status: 404,
				data: { message: 'no data here' },
			};
		}

		// Default status is 200
		return { data: { message: 'success' } };
	},
};

Running tests in parallel

Scenario Mock Server aims for mock data to be readily available while you're devloping locally, but also when you're running your tests.

The default behaviour of Scenario Mock Server is to run with one scenario active at a time. However, this falls down if you want to use multiple scenarios at the same time when running your tests in parallel. This is where 2 custom headers will become useful: sms-scenario-id and sms-context-id.

Note: These headers are not currently supported in cookieMode.

sms-scenario-id header

When this header is set to the scenario id of choice, regardless of what the current scenario is set to in the server, all responses will behave as if this was the currently set scenario instead.

sms-context-id header

This header must also be set when context is being used, otherwise context will reset on each call to the server when using the sms-scenario-id header.

Additional API paths

In addition to responding to API requests as set up by the currently active scenario a few additional endpoints exist that return json:

  • /scenarios
  • /select-scenario
  • /groups

These paths can be modified by using options (in case they clash with paths from scnearios).

/scenarios

Returns an array of scenarios available. Use GET.

type ApiScenario = {
	id: string;
	name: string;
	description: null | string;
	selected: boolean;
	group: null | string;
};

/select-scenario

Allows you to select which scenario is active. Use PUT and the following body:

{
	"scenarioId": "{SCENARIO_YOU_WANT_TO_SELECT}"
}

/groups

Returns an array of groups. Use GET.

type ApiGroup = {
	id: string;
	name: string;
};

API

createExpressApp

Returns the internal express instance.

function({ scenarios, options })

run

Returns an http server, with an additional kill method.

function({ scenarios, options })

scenarios

{ [scenarioId]: Array<Mock> | { name, description, context, mocks, extend, group } }

Property Type Default Description
scenarioId string required Scenario id. Used in calls to /select-scenario.
Mock Mock required See Mock for more details.
name string ${scenarioId} Scenario name. Used in the UI and available in /scenarios.
description string undefined Scenario description. Used in the UI and available in /scenarios.
context object undefined Used to set up data across API calls.
mocks Array<Mock> required See Mock for more details.
extend string undefined Use for extending other scenarios. Requires a scenario id.
group string undefined Used for grouping scenarios in the UI.

groups

{ [groupId]: groupName }

Property Type Default Description
groupId string required Group id. Matches with group assigned to scenarios.
groupName string required Used for heading in UI when groups exist.

options

{ port, uiPath, selectScenarioPath, scenariosPath, groupsPath, cookieMode, parallelContextSize } | defaults to {}

Property Type Default Description
port number 3000 Port that the http server runs on.
uiPath string / Path that the UI will load on. http://localhost:{port}{uiPath}
selectScenarioPath string /select-scenario API path for selecting a scenario. http://localhost:{port}{selectScenarioPath}
scenariosPath string /scenarios API path for getting scenarios. http://localhost:{port}{scenariosPath}
groupsPath string /groups API path for getting groups. http://localhost:{port}{groupsPath}
cookieMode boolean false Whether or not to store scenario selections in a cookie rather than directly in the server
parallelContextSize number 10 How large to make the number of contexts that can run in parallel. See Running tests in parallel

Types

Mock

HttpMock | GraphQlMock

See HttpMock and GraphQlMock for more details.

HttpMock

{ path, method, response }

Property Type Default Description
path string / RegExp required Path of endpoint. Must start with /.
method 'GET' / 'POST' / 'PUT' / 'DELETE' / 'PATCH' required HTTP method of endpoint.
response undefined / Response / HttpResponseFunction undefined Response, HttpResponseFunction.

Response

{ status, headers, data, delay }

Property Type Default Description
status number 200 HTTP status code for response.
headers object / undefined See description Key/value pairs of HTTP headers for response. Defaults to undefined when response is undefined, adds 'Content-Type': 'application/json' when response is not undefined and Content-Type is not supplied.
data null / string / object undefined Response data
delay number 0 Number of milliseconds before the response is returned.

HttpResponseFunction

function({ query, body, params, headers, context, updateContext }): response | Promise<response>

Property Type Default Description
query object {} query object as defined by express.
body object {} body object as defined by express.
params object {} params object as defined by express.
headers object {} Request headers, lowercase keys, string values only.
context object {} Data stored across API calls.
updateContext Function partialContext => updatedContext Used to update context. partialContext can either be an object or a function (context => partialContext).
response undefined / Response required Response.

GraphQlMock

{ path, method, operations }

Property Type Default Description
path string required Path of endpoint.
method 'GRAPHQL' required Indentifies this mock as a GraphQlMock.
operations Array<Operation> required List of operations for GraphQL endpoint. See Operation for more details.

Operation

{ type, name, response }

Property Type Default Description
type 'query' / 'mutation' required Type of operation.
name string required Name of operation.
response undefined / GraphQlResponse / GraphQlResponseFunction undefined GraphQlResponse, GraphQlResponseFunction.

GraphQlResponse

{ status, headers, data, delay }

Property Type Default Description
status number 200 HTTP status code for response.
headers object / undefined See description Key/value pairs of HTTP headers for response. Defaults to undefined when response is undefined, adds 'Content-Type': 'application/json' when response is not undefined and Content-Type is not supplied.
data { data?: null / object, errors?: array } undefined Response data
delay number 0 Number of milliseconds before the response is returned.

GraphQlResponseFunction

function({ variables, headers, context, updateContext }): response | Promise<response>

Property Type Default Description
variables object {} variables sent by client.
headers object {} Request headers, lowercase keys, string values only.
context object {} Data stored across API calls.
updateContext Function partialContext => updatedContext Used to update context. partialContext can either be an object or a function (context => partialContext).
response undefined / GraphQlResponse required GraphQlResponse.

Readme

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Install

npm i scenario-mock-server

Repository

github.com/kenneth-gray/scenario-mock-server

Homepage

github.com/kenneth-gray/scenario-mock-server#readme

Weekly Downloads

19

Version

1.2.0

License

MIT

Unpacked Size

84.5 kB

Total Files

6

Last publish

Collaborators

  • kenneth-gray
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