add basic API specs

.rubocop.yml

@@ -34,6 +34,7 @@ Metrics/MethodLength:
   Max: 30
   Exclude:
     - 'db/migrate/**'
+    - 'spec/**/*'
 
 Metrics/CyclomaticComplexity:
   Max: 15
@@ -46,6 +47,8 @@ Layout/LineLength:
 
 Metrics/AbcSize:
   Max: 45
+  Exclude:
+    - spec/**/*
 
 Metrics/ModuleLength:
   Max: 500