v3 - updated service plan cost

[#172146647](https://www.pivotaltracker.com/story/show/172146647)

Author: FelisiaM

app/presenters/v3/service_plan_presenter.rb

@@ -63,13 +63,13 @@ def costs
             metadata[:costs].each do |cost|
               unit = cost[:unit].to_s
               cost[:amount].each do |currency, amount|
-                unless currency.empty?
-                  cost_result << {
-                    currency: currency.to_s.upcase,
-                    amount: amount.to_f,
-                    unit: unit
-                  }
-                end
+                return [] if currency.empty?
+
+                cost_result << {
+                  currency: currency.to_s.upcase,
+                  amount: amount.to_f,
+                  unit: unit
+                }
               end
             end
           end
@@ -142,6 +142,7 @@ def costs_schema
               'properties' => {
                 'amount' => {
                   'type' => 'object',
+                  'minProperties' => 1,
                   'additionalProperties' => {
                     'type' => 'number'
                   }

spec/unit/presenters/v3/service_plan_presenter_spec.rb

@@ -211,35 +211,6 @@
         expect(result[:costs][0][:currency]).to eq('$')
         expect(result[:costs][0][:unit]).to eq('Daily')
       end
-
-      it 'skips when currency is empty string' do
-        service_plan =
-          VCAP::CloudController::ServicePlan.make(extra: '{"costs": [
-          {
-            "amount": {
-              "gpb": 0.06
-            },
-            "unit": "Daily"
-          },
-          {
-            "amount": {
-              "": 0.06,
-              "usd": 0.10
-            },
-            "unit": "Daily"
-          }
-        ]}')
-
-        result = described_class.new(service_plan).to_hash.deep_symbolize_keys
-
-        expect(result[:costs][0][:amount]).to eq(0.06)
-        expect(result[:costs][0][:currency]).to eq('GPB')
-        expect(result[:costs][0][:unit]).to eq('Daily')
-
-        expect(result[:costs][1][:amount]).to eq(0.10)
-        expect(result[:costs][1][:currency]).to eq('USD')
-        expect(result[:costs][1][:unit]).to eq('Daily')
-      end
     end
 
     context 'when plan has no cost' do
@@ -285,6 +256,12 @@
         ['unit is missing',
          '{
             "costs": [
+              {
+                "amount": {
+                  "usd": 649.0
+                },
+                "unit": "Daily"
+              },
               {
                 "amount": {
                   "usd": 649.0,
@@ -300,6 +277,12 @@
               {
                 "amount": {},
                 "unit": "Daily"
+              },
+              {
+                "amount": {
+                  "usd": 649.0
+                },
+                "unit": "Daily"
               }
             ]
            }'
@@ -315,6 +298,25 @@
               }
             ]
            }'
+        ],
+        ['currency is empty string',
+         '{
+             "costs": [
+                {
+                  "amount": {
+                    "gpb": 0.06
+                  },
+                  "unit": "Daily"
+                },
+                {
+                  "amount": {
+                    "": 0.06,
+                    "usd": 0.10
+                  },
+                  "unit": "Daily"
+                }
+            ]
+          }'
         ]
       ].each do |scenario, extra|
         it "returns empty cost array when #{scenario}" do