Add [Subreddit] subscribers (#3443)

* Add subreddit subscribers service file.

* Fix small detail in service and add the tests files.

* Apply suggested changes by the reviewer.

* Trying to make tests work.

* Update services/reddit/subreddit-subscribers.tester.js

Co-Authored-By: Caleb Cartwright <calebcartwright@users.noreply.github.com>

* Update services/reddit/subreddit-subscribers.tester.js

Co-Authored-By: Caleb Cartwright <calebcartwright@users.noreply.github.com>

* Apply suggested changes.

* Add different handler for non existing and invalid subreddits.

* Update services/reddit/subreddit-subscribers.service.js

Co-Authored-By: Caleb Cartwright <calebcartwright@users.noreply.github.com>

services/reddit/subreddit-subscribers.service.js

@@ -0,0 +1,83 @@
+'use strict'
+
+const { BaseJsonService, NotFound } = require('..')
+const Joi = require('joi')
+const { optionalNonNegativeInteger } = require('../validators')
+const { metric } = require('../text-formatters')
+
+const schema = Joi.object({
+  data: Joi.object({
+    subscribers: optionalNonNegativeInteger,
+  }).required(),
+}).required()
+
+module.exports = class SubredditSubscribers extends BaseJsonService {
+  static get category() {
+    return 'social'
+  }
+
+  static get route() {
+    return {
+      base: 'reddit/subreddit-subscribers',
+      pattern: ':subreddit',
+    }
+  }
+
+  static get examples() {
+    return [
+      {
+        title: 'Subreddit subscribers',
+        namedParams: { subreddit: 'drums' },
+        staticPreview: {
+          label: 'follow r/drums',
+          message: '77k',
+          color: 'red',
+          style: 'social',
+        },
+      },
+    ]
+  }
+
+  static get defaultBadgeData() {
+    return {
+      label: 'reddit',
+      namedLogo: 'reddit',
+    }
+  }
+
+  static render({ subreddit, subscribers }) {
+    return {
+      label: `follow r/${subreddit}`,
+      message: metric(subscribers),
+      color: 'red',
+      link: [`https://www.reddit.com/r/${subreddit}`],
+    }
+  }
+
+  async fetch({ subreddit }) {
+    return this._requestJson({
+      schema,
+      url: `https://www.reddit.com/r/${subreddit}/about.json`,
+      errorMessages: {
+        404: 'subreddit not found',
+      },
+    })
+  }
+
+  transform(json) {
+    const subscribers = json.data.subscribers
+    if (subscribers === undefined) {
+      throw new NotFound({ prettyMessage: 'subreddit not found' })
+    }
+    return { subscribers }
+  }
+
+  async handle({ subreddit }) {
+    const json = await this.fetch({ subreddit })
+    const { subscribers } = this.transform(json)
+    return this.constructor.render({
+      subreddit,
+      subscribers,
+    })
+  }
+}

services/reddit/subreddit-subscribers.tester.js

@@ -0,0 +1,25 @@
+'use strict'
+
+const { isMetric } = require('../test-validators')
+const t = (module.exports = require('../tester').createServiceTester())
+
+t.create('subreddit-subscribers (valid subreddit)')
+  .get('/drums.json')
+  .expectBadge({
+    label: 'follow r/drums',
+    message: isMetric,
+  })
+
+t.create('subreddit-subscribers (invalid subreddit)')
+  .get('/badfbasdfadfadfadfadfasdf.json')
+  .expectBadge({
+    label: 'reddit',
+    message: 'subreddit not found',
+  })
+
+t.create('subreddit-subscribers (not existing subreddit)')
+  .get('/not-a-real-rubreddit.json')
+  .expectBadge({
+    label: 'reddit',
+    message: 'subreddit not found',
+  })