Updates logic to filter highlights

Why are these changes being introduced:

* Showing highlights for fields that are already displayed in the main
  result view is redundant and clutters the interface.
* We updated the displayed fields, but did not update the highlight
  filtering logic to match.

Relevant ticket(s):

* https://mitlibraries.atlassian.net/browse/USE-300

How does this address that need:

* Updates the list of displayed fields used to filter highlights
  to match the current set of displayed fields.
* Updates tests to match the new logic.

Document any side effects to this change:

* We are filtering out `citation` even thought we don't display it for
  timdex results. This is intentional as citation data is often
  redundant with other displayed fields like title and contributors.

Author: JPrevost

app/helpers/search_helper.rb

@@ -1,6 +1,8 @@
 module SearchHelper
+  # These fields are used to filter out highlights that are already displayed in the main result view. Keep in mind these values need to be the names of fields in TIMDEX, not the normalized record keys.
   def displayed_fields
-    ['title', 'title.exact_value', 'content_type', 'dates.value', 'contributors.value']
+    ['title', 'title.exact_value', 'content_type', 'dates.value', 'contributors.value', 'summary', 'citation',
+     'subjects.value']
   end
 
   def trim_highlights(result)

test/controllers/search_controller_test.rb

@@ -100,7 +100,7 @@ def mock_timdex_search_success
       'contributors' => [{ 'value' => 'Foo Barston', 'kind' => 'Creator' }],
       'highlight' => [
         {
-          'matchedField' => 'summary',
+          'matchedField' => 'notes',
           'matchedPhrases' => ['<span>sample</span> document']
         }
       ],

test/helpers/search_helper_test.rb

@@ -13,17 +13,17 @@ class SearchHelperTest < ActionView::TestCase
   end
 
   test 'does not remove undisplayed fields from highlights' do
-    result = { highlight: [{ 'matchedField' => 'summary', 'matchedPhrases' => 'Have some data' }] }
-    assert_equal [{ 'matchedField' => 'summary', 'matchedPhrases' => 'Have some data' }], trim_highlights(result)
+    result = { highlight: [{ 'matchedField' => 'notes', 'matchedPhrases' => 'Have some data' }] }
+    assert_equal [{ 'matchedField' => 'notes', 'matchedPhrases' => 'Have some data' }], trim_highlights(result)
   end
 
   test 'returns correct set of highlights when result includes displayed and undisplayed fields' do
     result = { highlight: [{ 'matchedField' => 'title', 'matchedPhrases' => 'Very important data' },
                            { 'matchedField' => 'content_type', 'matchedPhrases' => 'Dataset' },
-                           { 'matchedField' => 'summary', 'matchedPhrases' => '2022' },
-                           { 'matchedField' => 'citation', 'matchedPhrases' => 'Datascientist, Jane' }] }
-    assert_equal [{ 'matchedField' => 'summary', 'matchedPhrases' => '2022' },
-                  { 'matchedField' => 'citation', 'matchedPhrases' => 'Datascientist, Jane' }], trim_highlights(result)
+                           { 'matchedField' => 'numbering', 'matchedPhrases' => '2022' },
+                           { 'matchedField' => 'notes', 'matchedPhrases' => 'Datascientist, Jane' }] }
+    assert_equal [{ 'matchedField' => 'numbering', 'matchedPhrases' => '2022' },
+                  { 'matchedField' => 'notes', 'matchedPhrases' => 'Datascientist, Jane' }], trim_highlights(result)
   end
 
   test 'parse_geo_dates returns issued over coverage' do