Test for searches with multiple detections

** Why are these changes being introduced:

* Some of our search traffic may meet conditions of multiple detections.
  We need our reports to correctly count these events in all relevant
  categories.

** Relevant ticket(s):

* https://mitlibraries.atlassian.net/browse/tco-43

** How does this address that need:

* This starts by creating a single term fixture that should trigger more
  than one detector - a citation which includes both a DOI and PubMedID
  for an article.

* A new test is also created, which generates a report based only on
  a search for this term, which asserts that two different counters
  should have non-zero numbers.

** Document any side effects to this change:

* It is a bit awkward to have too many tests that start by deleting
  existing records from our fixtures - but we're not yet at the point
  where we'd need something like a factory. We'll talk about that at
  some point if the need more clearly arises.

test/fixtures/terms.yml

@@ -28,3 +28,6 @@ isbn_9781319145446:
 
 journal_nature_medicine:
   phrase: 'nature medicine'
+
+multiple_detections:
+  phrase: 'Environmental and Health Impacts of Air Pollution: A Review. Frontiers in Public Health. PMID: 32154200. DOI: 10.3389/fpubh.2020.00014'

test/models/metrics/algorithms_test.rb

@@ -55,6 +55,18 @@ class Algorithms < ActiveSupport::TestCase
     assert_equal 2, aggregate.unmatched
   end
 
+  test 'searches with multiple patterns are accounted for correctly' do
+    # Drop all search events to ensure the report has only what we care about.
+    SearchEvent.delete_all
+
+    SearchEvent.create(term: terms(:multiple_detections), source: 'test')
+
+    aggregate = Metrics::Algorithms.new.generate(DateTime.now)
+
+    assert_equal 1, aggregate.doi
+    assert_equal 1, aggregate.pmid
+  end
+
   test 'creating lots of searchevents leads to correct data for monthly' do
     # drop all searchevents to make math easier and minimize fragility over time as more fixtures are created
     SearchEvent.delete_all
@@ -97,7 +109,7 @@ class Algorithms < ActiveSupport::TestCase
   test 'dois counts are included in total aggregation' do
     aggregate = Metrics::Algorithms.new.generate
 
-    assert_equal 1, aggregate.doi
+    assert_equal 2, aggregate.doi
   end
 
   test 'issns counts are included in total aggregation' do
@@ -115,7 +127,7 @@ class Algorithms < ActiveSupport::TestCase
   test 'pmids counts are included in total aggregation' do
     aggregate = Metrics::Algorithms.new.generate
 
-    assert_equal 2, aggregate.pmid
+    assert_equal 3, aggregate.pmid
   end
 
   test 'journal exact counts are included in total aggregation' do