Implement initial GraphQL interface

Why these changes are being introduced:

We need a GraphQL interface to record SearchEvents from TACOS
consumers.

Relevant ticket(s):

https://mitlibraries.atlassian.net/browse/ENGX-234

How this addresses that need:

This adds a SearchEvent type and corresponding query field that
returns information about the search event and creates a new
SearchEvent (and Term, if applicable).

Side effects of this change:

* Removed a couple of generated GraphQL test fields.
* Miscellaneous rubocop fixes.

app/graphql/types/mutation_type.rb

@@ -1,12 +1,4 @@
-# frozen_string_literal: true
-
 module Types
   class MutationType < Types::BaseObject
-    # TODO: remove me
-    field :test_field, String, null: false,
-      description: "An example field added by the generator"
-    def test_field
-      "Hello World"
-    end
   end
 end

app/graphql/types/query_type.rb

@@ -2,16 +2,17 @@
 
 module Types
   class QueryType < Types::BaseObject
-    field :node, Types::NodeType, null: true, description: "Fetches an object given its ID." do
-      argument :id, ID, required: true, description: "ID of the object."
+    field :node, Types::NodeType, null: true, description: 'Fetches an object given its ID.' do
+      argument :id, ID, required: true, description: 'ID of the object.'
     end
 
     def node(id:)
       context.schema.object_from_id(id, context)
     end
 
-    field :nodes, [Types::NodeType, null: true], null: true, description: "Fetches a list of objects given a list of IDs." do
-      argument :ids, [ID], required: true, description: "IDs of the objects."
+    field :nodes, [Types::NodeType, { null: true }], null: true,
+                                                     description: 'Fetches a list of objects given a list of IDs.' do
+      argument :ids, [ID], required: true, description: 'IDs of the objects.'
     end
 
     def nodes(ids:)
@@ -21,11 +22,15 @@ def nodes(ids:)
     # Add root-level fields here.
     # They will be entry points for queries on your schema.
 
-    # TODO: remove me
-    field :test_field, String, null: false,
-      description: "An example field added by the generator"
-    def test_field
-      "Hello World!"
+    field :log_search_event, SearchEventType, null: false,
+                                              description: 'Log a search and return information about it.' do
+      argument :search_term, String, required: true
+      argument :source_system, String, required: true
+    end
+
+    def log_search_event(search_term:, source_system:)
+      term = Term.create_or_find_by!(phrase: search_term)
+      term.search_events.create!(source: source_system)
     end
   end
 end

app/graphql/types/search_event_type.rb

@@ -0,0 +1,11 @@
+# frozen_string_literal: true
+
+module Types
+  class SearchEventType < Types::BaseObject
+    field :id, ID, null: false
+    field :term_id, Integer
+    field :source, String
+    field :created_at, GraphQL::Types::ISO8601DateTime, null: false
+    field :updated_at, GraphQL::Types::ISO8601DateTime, null: false
+  end
+end

test/controllers/graphql_controller_test.rb

@@ -0,0 +1,51 @@
+require 'test_helper'
+
+class GraphqlControllerTest < ActionDispatch::IntegrationTest
+  test 'search event query returns relevant data' do
+    post '/graphql', params: { query: '{
+                                 logSearchEvent(sourceSystem: "bento", searchTerm: "range life") {
+                                   termId
+                                   source
+                                   createdAt
+                                   updatedAt
+                                 }
+                               }' }
+    assert_equal(200, response.status)
+    json = JSON.parse(response.body)
+    term_id = Term.last.id
+
+    assert_equal 'bento', json['data']['logSearchEvent']['source']
+    assert_equal term_id, json['data']['logSearchEvent']['termId']
+    assert_equal Date.today, json['data']['logSearchEvent']['createdAt'].to_date
+    assert_equal Date.today, json['data']['logSearchEvent']['updatedAt'].to_date
+  end
+
+  test 'search event query creates a new term if one does not exist' do
+    initial_term_count = Term.count
+    post '/graphql', params: { query: '{
+                                 logSearchEvent(sourceSystem: "bento", searchTerm: "range life") {
+                                   termId
+                                   source
+                                   createdAt
+                                   updatedAt
+                                 }
+                               }' }
+    assert_equal(200, response.status)
+    assert_equal Term.count, (initial_term_count + 1)
+    assert_equal 'range life', Term.last.phrase
+  end
+
+  test 'search event query does not create a new term if phrase is already stored' do
+    initial_term_count = Term.count
+    post '/graphql', params: { query: '{
+                                 logSearchEvent(sourceSystem: "timdex", searchTerm: "Super cool search") {
+                                   termId
+                                   source
+                                   createdAt
+                                   updatedAt
+                                 }
+                               }' }
+    assert_equal(200, response.status)
+    assert_equal Term.count, initial_term_count
+  end
+end