Implement All Contributors Badge, run [GitHubAllContributors] (#5163)

* feat: added all-contributors badge and test

* Update services/github/github-all-contributors.service.js

Updated to schema to ensure the array always exists

Co-authored-by: Caleb Cartwright <calebcartwright@users.noreply.github.com>

* fix: added branch to parameters

Co-authored-by: Caleb Cartwright <calebcartwright@users.noreply.github.com>

services/github/github-all-contributors.service.js

@@ -0,0 +1,60 @@
+'use strict'
+
+const Joi = require('@hapi/joi')
+const { renderContributorBadge } = require('../contributor-count')
+const { ConditionalGithubAuthV3Service } = require('./github-auth-service')
+const { fetchJsonFromRepo } = require('./github-common-fetch')
+const { documentation } = require('./github-helpers')
+
+const schema = Joi.object({
+  contributors: Joi.array().required(),
+}).required()
+
+module.exports = class GithubAllContributorsService extends ConditionalGithubAuthV3Service {
+  static get category() {
+    return 'activity'
+  }
+
+  static get route() {
+    return {
+      base: 'github/all-contributors',
+      pattern: ':user/:repo/:branch*',
+    }
+  }
+
+  static get examples() {
+    return [
+      {
+        title: 'Github All Contributors',
+        namedParams: {
+          repo: 'all-contributors',
+          user: 'all-contributors',
+          branch: 'master',
+        },
+        staticPreview: this.render({ contributorCount: 66 }),
+        documentation,
+      },
+    ]
+  }
+
+  static get defaultBadgeData() {
+    return { label: 'all contributors' }
+  }
+
+  static render({ contributorCount }) {
+    return renderContributorBadge({ contributorCount })
+  }
+
+  async handle({ user, repo, branch }) {
+    const { contributors } = await fetchJsonFromRepo(this, {
+      schema,
+      user,
+      repo,
+      branch,
+      filename: '.all-contributorsrc',
+    })
+
+    const contributorCount = contributors.length
+    return this.constructor.render({ contributorCount })
+  }
+}

services/github/github-all-contributors.tester.js

@@ -0,0 +1,16 @@
+'use strict'
+
+const t = (module.exports = require('../tester').createServiceTester())
+const { isMetric } = require('../test-validators')
+
+t.create('all-contributors repo')
+  .get('/all-contributors/all-contributors.json')
+  .expectBadge({
+    label: 'all contributors',
+    message: isMetric,
+  })
+
+t.create('shields repo (not found)').get('/badges/shields.json').expectBadge({
+  label: 'all contributors',
+  message: 'repo not found, branch not found, or .all-contributorsrc missing',
+})