feat(backends): Enable creation of backends

Backends can now be created using `createBackend(version, data)`. In addition, safe creation/update
is possible with `writeBackend(version, name, data)`

fixes #5

README.md

@@ -269,6 +269,7 @@ HTTP status code can be retrieved. Known error status codes include:</p>
     * [.readDomains(version)](#Fastly+readDomains) ⇒ <code>Promise</code>
     * [.readBackends(version)](#Fastly+readBackends) ⇒ <code>Promise</code>
     * [.updateBackend(version, name, data)](#Fastly+updateBackend) ⇒ <code>Promise</code>
+    * [.createBackend(version, data)](#Fastly+createBackend) ⇒ <code>Promise</code>
     * [.createSnippet(version, data)](#Fastly+createSnippet) ⇒ <code>Promise</code>
     * [.updateSnippet(version, name, data)](#Fastly+updateSnippet) ⇒ <code>Promise</code>
     * [.createVCL(version, data)](#Fastly+createVCL) ⇒ <code>Promise</code>
@@ -749,6 +750,21 @@ instance.updateBackend('34', 'slow-server', { name: 'fast-server' })
      console.log(err.message);
    });
 ```
+<a name="Fastly+createBackend"></a>
+
+#### fastly.createBackend(version, data) ⇒ <code>Promise</code>
+Create a new backend for a particular service and version.
+
+**Kind**: instance method of [<code>Fastly</code>](#Fastly)  
+**Returns**: <code>Promise</code> - The reponse object.  
+**Fulfil**: [<code>Response</code>](#Response)  
+**See**: https://docs.fastly.com/api/config#backend_85c170418ee71191dbb3b5046aeb6c2c  
+
+| Param | Type | Description |
+| --- | --- | --- |
+| version | <code>number</code> | The version number (current if omitted). |
+| data | <code>Object</code> | The backend definition. |
+
 <a name="Fastly+createSnippet"></a>
 
 #### fastly.createSnippet(version, data) ⇒ <code>Promise</code>

src/index.js

@@ -277,6 +277,7 @@ class Fastly {
 
     this.writeVCL = this.upsertFn(this.createVCL, this.updateVCL);
     this.writeSnippet = this.upsertFn(this.createSnippet, this.updateSnippet);
+    this.writeBackend = this.upsertFn(this.createBackend, this.updateBackend);
   }
   /**
    * @typedef {Object} FastlyError
@@ -686,6 +687,19 @@ class Fastly {
   async updateBackend(version, name, data) {
     return this.request.put(`/service/${this.service_id}/version/${await this.getVersion(version, 'current')}/backend/${encodeURIComponent(name)}`, data);
   }
+
+  /**
+   * Create a new backend for a particular service and version.
+   *
+   * @see https://docs.fastly.com/api/config#backend_85c170418ee71191dbb3b5046aeb6c2c
+   * @param {number} version - The version number (current if omitted).
+   * @param {Object} data - The backend definition.
+   * @returns {Promise} The reponse object.
+   * @fulfil {Response}
+   */
+  async createBackend(version, data) {
+    return this.request.post(`/service/${this.service_id}/version/${await this.getVersion(version, 'current')}/backend`, data);
+  }
   /**
    * @typedef {Object} Snippet
    * @property {String} name The name of the snippet, as visible in the Fastly UI

test/createBackend.test.js

@@ -0,0 +1,84 @@
+'use strict';
+
+/* eslint-env mocha */
+
+const nock = require('nock');
+const expect = require('expect');
+const config = require('../src/config');
+const fastlyPromises = require('../src/index');
+const response = require('./response/createBackend.response');
+
+describe('#createBackend', () => {
+  const fastly = fastlyPromises('923b6bd5266a7f932e41962755bd4254', 'SU1Z0isxPaozGVKXdv0eY');
+  let res;
+
+  nock(config.mainEntryPoint)
+    .post('/service/SU1Z0isxPaozGVKXdv0eY/version/1/backend')
+    .reply(200, response.createBackend);
+
+  before(async () => {
+    res = await fastly.createBackend(1, {
+      ipv4: '127.0.0.1',
+      name: 'backend-name',
+      port: 80,
+    });
+  });
+
+  it('response should be a status 200', () => {
+    expect(res.status).toBe(200);
+  });
+
+  it('response body should exist', () => {
+    expect(res.data).toBeTruthy();
+  });
+
+  it('response body should be an object', () => {
+    expect(typeof res.data).toBe('object');
+  });
+
+  it('response body properties should be created', () => {
+    expect(res.data.name).toBe('backend-name');
+    expect(res.data.port).toBe(80);
+    expect(res.data.ipv4).toBe('127.0.0.1');
+  });
+
+  it('response body should contain all properties', () => {
+    [
+      'address',
+      'auto_loadbalance',
+      'between_bytes_timeout',
+      'client_cert',
+      'comment',
+      'connect_timeout',
+      'error_threshold',
+      'first_byte_timeout',
+      'healthcheck',
+      'hostname',
+      'ipv4',
+      'ipv6',
+      'locked',
+      'max_conn',
+      'max_tls_version',
+      'min_tls_version',
+      'name',
+      'port',
+      'request_condition',
+      'service_id',
+      'shield',
+      'override_host',
+      'ssl_ca_cert',
+      'ssl_cert_hostname',
+      'ssl_check_cert',
+      'ssl_ciphers',
+      'ssl_client_cert',
+      'ssl_client_key',
+      'ssl_hostname',
+      'ssl_sni_hostname',
+      'use_ssl',
+      'version',
+      'weight',
+    ].forEach((e) => {
+      expect(Object.keys(res.data)).toContain(e);
+    });
+  });
+});

test/response/createBackend.response.js

@@ -0,0 +1,37 @@
+'use strict';
+
+module.exports.createBackend = {
+  address: '127.0.0.1',
+  auto_loadbalance: false,
+  between_bytes_timeout: 10000,
+  client_cert: null,
+  comment: '',
+  connect_timeout: 1000,
+  error_threshold: 0,
+  first_byte_timeout: 15000,
+  healthcheck: null,
+  hostname: null,
+  ipv4: '127.0.0.1',
+  ipv6: null,
+  locked: true,
+  max_conn: 200,
+  max_tls_version: null,
+  min_tls_version: null,
+  name: 'backend-name',
+  port: 80,
+  request_condition: '',
+  service_id: 'SU1Z0isxPaozGVKXdv0eY',
+  shield: null,
+  override_host: null,
+  ssl_ca_cert: null,
+  ssl_cert_hostname: null,
+  ssl_check_cert: true,
+  ssl_ciphers: null,
+  ssl_client_cert: null,
+  ssl_client_key: null,
+  ssl_hostname: null,
+  ssl_sni_hostname: null,
+  use_ssl: false,
+  version: 1,
+  weight: 100,
+};