Split up [github] testers (#2560)

- Update github contributors badge for `create-service-tester`.

services/github/github-tag.tester.js

@@ -0,0 +1,51 @@
+'use strict'
+
+const Joi = require('joi')
+const { colorScheme: colorsB } = require('../test-helpers')
+
+const t = (module.exports = require('../create-service-tester')())
+
+t.create('Tag')
+  .get('/tag/photonstorm/phaser.json')
+  .expectJSONTypes(Joi.object().keys({ name: 'tag', value: Joi.string() }))
+
+t.create('Tag (inc pre-release)')
+  .get('/tag-pre/photonstorm/phaser.json')
+  .expectJSONTypes(Joi.object().keys({ name: 'tag', value: Joi.string() }))
+
+t.create('Tag (repo not found)')
+  .get('/tag/badges/helmets.json')
+  .expectJSON({ name: 'tag', value: 'repo not found' })
+
+const tagsFixture = [
+  { name: 'cheese' }, // any old string
+  { name: 'v1.3-beta3' }, // semver pre-release
+  { name: 'v1.2' }, // semver release
+]
+
+t.create('Tag (mocked response, no pre-releases, semver ordering)')
+  .get('/tag/foo/bar.json?style=_shields_test')
+  .intercept(nock =>
+    nock('https://api.github.com')
+      .get('/repos/foo/bar/tags')
+      .reply(200, tagsFixture)
+  )
+  .expectJSON({ name: 'tag', value: 'v1.2', colorB: colorsB.blue })
+
+t.create('Tag (mocked response, include pre-releases, semver ordering)')
+  .get('/tag-pre/foo/bar.json?style=_shields_test')
+  .intercept(nock =>
+    nock('https://api.github.com')
+      .get('/repos/foo/bar/tags')
+      .reply(200, tagsFixture)
+  )
+  .expectJSON({ name: 'tag', value: 'v1.3-beta3', colorB: colorsB.orange })
+
+t.create('Tag (mocked response, date ordering)')
+  .get('/tag-date/foo/bar.json?style=_shields_test')
+  .intercept(nock =>
+    nock('https://api.github.com')
+      .get('/repos/foo/bar/tags')
+      .reply(200, tagsFixture)
+  )
+  .expectJSON({ name: 'tag', value: 'cheese', colorB: colorsB.blue })