fix [gem] rank badge (#2659)

The ranking endpoints return a value for every day. This is rare, but it looks like sometimes this can be `null` (for example if you call http://bestgems.org/api/v1/gems/rack/daily_ranking.json the rank was `null` on `2013-07-02` ) and if the rank has _ever_ been `null` for a package in the past, the schema will fail validating the response.

This modifies the schema to allow a `null` value and adds a case to handle if the rank is `null` today.

closes #2647

services/gem/gem-rank.service.js

@@ -5,14 +5,17 @@ const Joi = require('joi')
 const BaseJsonService = require('../base-json')
 const { floorCount: floorCountColor } = require('../../lib/color-formatters')
 const { ordinalNumber } = require('../../lib/text-formatters')
-const { nonNegativeInteger } = require('../validators')
+const { InvalidResponse } = require('../errors')
 
 const keywords = ['ruby']
 
 const totalSchema = Joi.array()
   .items(
     Joi.object({
-      total_ranking: nonNegativeInteger,
+      total_ranking: Joi.number()
+        .integer()
+        .min(0)
+        .allow(null),
     })
   )
   .min(1)
@@ -20,7 +23,10 @@ const totalSchema = Joi.array()
 const dailySchema = Joi.array()
   .items(
     Joi.object({
-      daily_ranking: nonNegativeInteger,
+      daily_ranking: Joi.number()
+        .integer()
+        .min(0)
+        .allow(null),
     })
   )
   .min(1)
@@ -56,6 +62,9 @@ module.exports = class GemRank extends BaseJsonService {
   async handle({ period, gem }) {
     const json = await this.fetch({ period, gem })
     const rank = period === 'rt' ? json[0].total_ranking : json[0].daily_ranking
+    if (rank == null) {
+      throw new InvalidResponse({ prettyMessage: 'invalid rank' })
+    }
     return this.constructor.render({ period, rank })
   }
 

services/gem/gem-rank.tester.js

@@ -19,7 +19,7 @@ t.create('total rank (valid)')
   )
 
 t.create('daily rank (valid)')
-  .get('/rd/rspec-puppet-facts.json')
+  .get('/rd/rails.json')
   .expectJSONTypes(
     Joi.object().keys({
       name: 'rank',
@@ -30,3 +30,17 @@ t.create('daily rank (valid)')
 t.create('rank (not found)')
   .get('/rt/not-a-package.json')
   .expectJSON({ name: 'rank', value: 'not found' })
+
+t.create('rank is null')
+  .get('/rd/rails.json')
+  .intercept(nock =>
+    nock('http://bestgems.org')
+      .get('/api/v1/gems/rails/daily_ranking.json')
+      .reply(200, [
+        {
+          date: '2019-01-06',
+          daily_ranking: null,
+        },
+      ])
+  )
+  .expectJSON({ name: 'rank', value: 'invalid rank' })