Version: 1.9.0

Defining fixtures and behaviors

Installation#

Follow the installation example in the intro in order to install and configure an npm script for starting the Mocks Server in your project.

Files structure#

Create a /mocks folder in your project root, containing a behaviors.json file, and a fixtures/users.json file:

/your/awesome/project
|-- node_modules
|-- src
|-- mocks
|   |-- behaviors.json
|   |-- fixtures
|   |   |-- users.json
|-- package.json

You can create as many files as you want in the mocks folder, no matter if they contain "behaviors", "fixtures" or both. The Mocks Server will load all of them automatically wherever they are. This structure is only a suggestion.

Create an users fixture#

Now we are going to add a fixture to the /mocks/fixtures/users.json file, which will be used when GET requests are received in the /api/users path or our "api mock":

// mocks/fixtures/users.json
{
  "id": "get-users",
  "url": "/api/users",
  "method": "GET",
  "response": {
    "status": 200,
    "body": [
      {
        "id": 1,
        "name": "John Doe"
      },
      {
        "id": 2,
        "name": "Jane Doe"
      }
    ]
  }
}

Fixtures format

Read the get started with fixtures chapter to know all possible fixtures properties.

Export a default behavior#

Create an "standard" behavior in the mocks/behaviors.json file, containing the recently created "users" fixture.

// mocks/behaviors.json
{
  "id": "standard",
  "fixtures": ["get-users"]
}

Fixtures format

Read the get started with behaviors chapter to know all possible behaviors properties.

Start the Mocks Server#

npm run mocks-server

The interactive CLI will be started:

Interactive CLI

Browse to http://localhost:3100/api/users to check that Mocks Server is serving your users collection fixture at the expected url. You should see the response in your browser:

[{"id":1,"name":"John Doe"},{"id":2,"name":"Jane Doe"}]

Add fixture for getting an specific user#

Now we have the mocked the response for the "users" collection. Let's add the fixture for getting an specific user:

Convert the object in mocks/fixtures/users.json into an array, and add the new "get-user" fixture to it:

// mocks/fixtures/users.json
[
  // ...
  {
    "id": "get-user",
    "url": "/api/users/:id",
    "method": "GET",
    "response": {
      "status": 200,
      "body": {
        "id": 1,
        "name": "John Doe"
      }
    }
  }
]

Add the fixture to the "standard" behavior:

// mocks/behaviors.json
{
  "id": "standard",
  "fixtures": ["get-users", "get-user"]
}

The Mocks Server is watching for file changes, so your fixtures should have been refreshed automatically.

Browse to http://localhost:3100/api/users/1. You should see the response in your browser:

{"id":1,"name":"John Doe"}

But... even when you change the user id in the request, (http://localhost:3100/api/users/2) obviously the response will be still the same:

{"id":1,"name":"John Doe"}

Well, this is the expected behavior of a mock server, but you can add a new "behavior" to change the response:

Add another behavior#

Let's add another "GET user" fixture, but now it will be always responded with the second user:

// mocks/fixtures/users.json
[
  // ...
  {
    "id": "get-user-2",
    "url": "/api/users/:id",
    "method": "GET",
    "response": {
      "status": 200,
      "body": {
        "id": 2,
        "name": "Jane Doe"
      }
    }
  }
]

And let's add a new Behavior extending the standard one:

// mocks/behaviors.json
[
  {
    "id": "standard",
    "fixtures": ["get-users", "get-user"]
  },
  {
    "id": "user2",
    "from": "standard",
    "fixtures": ["get-user-2"]
  }
]

Now the Mocks Server CLI indicates that it has two behaviors available.

Available behaviors

Change current behavior#

Use the CLI to change current behavior:

Available behaviors

Browse to http://localhost:3100/api/users/2. You should now see the second user:

{"id":2,"name":"Jane Doe"}

Browse to http://localhost:3100/api/users. Users collection is also available:

[{"id":1,"name":"John Doe"},{"id":2,"name":"Jane Doe"}]

Add multiple fixtures and behaviors#

Now you've seen what Mocks Server can do, you can add as much fixtures you need for your development or end-to-end tests, (such as error responses cases, "users" with very long name, another special cases, etc.)

You can combine all your fixtures in as much behaviors as you need, extending them or creating them from scratch.

And, very important, you can easily change the current behavior using the interactive CLI or the REST API while the server is running, which will make your development or tests environments very much agile and flexible, and not api dependant.