Add Github package.json dependency version badge (#2709)

Close #2259 which is mostly about a `package.json` dependency badge.

services/github/github-package-json.tester.js

@@ -3,6 +3,7 @@
 const Joi = require('joi')
 const ServiceTester = require('../service-tester')
 const { isSemver } = require('../test-validators')
+const { semverRange } = require('../validators')
 
 const t = (module.exports = new ServiceTester({
   id: 'GithubPackageJson',
@@ -23,7 +24,7 @@ t.create('Package version (repo not found)')
   .get('/v/badges/helmets.json')
   .expectJSON({
     name: 'version',
-    value: 'package.json missing or repo not found',
+    value: 'repo not found, branch not found, or package.json missing',
   })
 
 t.create('Package name')
@@ -46,3 +47,57 @@ t.create('Package array')
 t.create('Package object')
   .get('/dependencies/badges/shields.json')
   .expectJSON({ name: 'package.json', value: 'invalid key value' })
+
+t.create('Peer dependency version')
+  .get('/dependency-version/paulmelnikow/react-boxplot/peer/react.json')
+  .expectJSONTypes(
+    Joi.object({
+      name: 'react',
+      value: semverRange,
+    })
+  )
+
+t.create('Dev dependency version')
+  .get(
+    '/dependency-version/paulmelnikow/react-boxplot/dev/react.json?label=react%20tested'
+  )
+  .expectJSONTypes(
+    Joi.object({
+      name: 'react tested',
+      value: semverRange,
+    })
+  )
+
+t.create('Prod prod dependency version')
+  .get('/dependency-version/paulmelnikow/react-boxplot/simple-statistics.json')
+  .expectJSONTypes(
+    Joi.object({
+      name: 'simple-statistics',
+      value: semverRange,
+    })
+  )
+
+t.create('Scoped dependency')
+  .get('/dependency-version/badges/shields/dev/@babel/core.json')
+  .expectJSONTypes(
+    Joi.object({
+      name: '@babel/core',
+      value: semverRange,
+    })
+  )
+
+t.create('Scoped dependency on branch')
+  .get('/dependency-version/zeit/next.js/dev/babel-eslint/alpha.json')
+  .expectJSONTypes(
+    Joi.object({
+      name: 'babel-eslint',
+      value: semverRange,
+    })
+  )
+
+t.create('Unknown dependency')
+  .get('/dependency-version/paulmelnikow/react-boxplot/dev/i-made-this-up.json')
+  .expectJSON({
+    name: 'dependency',
+    value: 'dev dependency not found',
+  })