Improve specs and GraphQL field descriptions

ee/app/graphql/resolvers/epic_resolver.rb

@@ -24,11 +24,11 @@ module Resolvers
 
     argument :author_username, GraphQL::STRING_TYPE,
              required: false,
-             description: 'List epics for author'
+             description: 'Filter epics by author'
 
     argument :label_name, [GraphQL::STRING_TYPE],
              required: false,
-             description: 'List epics that has given label names'
+             description: 'Filter epics by labels'
 
     argument :start_date, Types::TimeType,
              required: false,

ee/spec/graphql/resolvers/epic_resolver_spec.rb

@@ -154,25 +154,25 @@ describe Resolvers::EpicResolver do
         it 'orders epics by start date in descending order' do
           epics = resolve_epics(sort: 'start_date_desc')
 
-          expect(epics).to match_array([epic3, epic2, epic1])
+          expect(epics).to eq([epic1, epic2, epic3])
         end
 
         it 'orders epics by start date in ascending order' do
           epics = resolve_epics(sort: 'start_date_asc')
 
-          expect(epics).to match_array([epic1, epic2, epic3])
+          expect(epics).to eq([epic3, epic2, epic1])
         end
 
         it 'orders epics by end date in descending order' do
-          epics = resolve_epics(sort: 'start_date_asc')
+          epics = resolve_epics(sort: 'end_date_desc')
 
-          expect(epics).to match_array([epic1, epic2, epic3])
+          expect(epics).to eq([epic3, epic2, epic1])
         end
 
         it 'orders epics by end date in ascending order' do
-          epics = resolve_epics(sort: 'start_date_asc')
+          epics = resolve_epics(sort: 'end_date_asc')
 
-          expect(epics).to match_array([epic3, epic2, epic1])
+          expect(epics).to eq([epic1, epic2, epic3])
         end
       end