Ensure Patient#teams doesn't return duplicates

If a patient belongs to multiple sessions for the same team (which is
normal) then this method returns the same team multiple times. Although
this is not really an issue in the way this method is used, it does
cause a problem when creating archive reasons when the patient is
deceased as we try and create multiple archive reasons for the same team
which results in a unique constraint failing.

Sentry-Issue: 6902363114

Author: thomasleese

app/models/patient.rb

@@ -428,12 +428,12 @@ def sessions
   end
 
   def teams
-    Team.left_outer_joins(:sessions).joins(<<-SQL)
-        INNER JOIN patient_locations
-        ON patient_locations.patient_id = #{id}
-        AND patient_locations.location_id = sessions.location_id
-        AND patient_locations.academic_year = sessions.academic_year 
-      SQL
+    Team.distinct.joins(:sessions).joins(<<-SQL)
+      INNER JOIN patient_locations
+      ON patient_locations.patient_id = #{id}
+      AND patient_locations.location_id = sessions.location_id
+      AND patient_locations.academic_year = sessions.academic_year 
+    SQL
   end
 
   def archived?(team:)

spec/models/patient_spec.rb

@@ -51,6 +51,22 @@
 describe Patient do
   describe "associations" do
     it { should have_many(:archive_reasons) }
+
+    describe "#vaccination_records" do
+      subject(:vaccination_records) { patient.vaccination_records }
+
+      let(:patient) { create(:patient) }
+      let(:programme) { create(:programme) }
+      let(:kept_vaccination_record) do
+        create(:vaccination_record, patient:, programme:)
+      end
+      let(:discarded_vaccination_record) do
+        create(:vaccination_record, :discarded, patient:, programme:)
+      end
+
+      it { should include(kept_vaccination_record) }
+      it { should_not include(discarded_vaccination_record) }
+    end
   end
 
   describe "scopes" do
@@ -464,20 +480,39 @@
     it { should normalize(:address_postcode).from(" SW111AA ").to("SW11 1AA") }
   end
 
-  describe "#vaccination_records" do
-    subject(:vaccination_records) { patient.vaccination_records }
+  describe "#teams" do
+    subject(:teams) { patient.teams }
 
     let(:patient) { create(:patient) }
-    let(:programme) { create(:programme) }
-    let(:kept_vaccination_record) do
-      create(:vaccination_record, patient:, programme:)
-    end
-    let(:discarded_vaccination_record) do
-      create(:vaccination_record, :discarded, patient:, programme:)
-    end
 
-    it { should include(kept_vaccination_record) }
-    it { should_not include(discarded_vaccination_record) }
+    it { should be_empty }
+
+    context "when a team exists" do
+      let!(:team) { create(:team) }
+
+      it { should be_empty }
+
+      context "and the patient belongs to the team" do
+        let(:session) { create(:session, team:) }
+        let(:patient) { create(:patient, session:) }
+
+        it { should include(team) }
+      end
+
+      context "and the patient belongs to multiple sessions under the same team" do
+        let(:menacwy_session) do
+          create(:session, team:, programmes: [create(:programme, :menacwy)])
+        end
+        let(:td_ipv_session) do
+          create(:session, team:, programmes: [create(:programme, :td_ipv)])
+        end
+        let(:patient) { create(:patient, session: menacwy_session) }
+
+        before { create(:patient_location, patient:, session: td_ipv_session) }
+
+        it { should contain_exactly(team) }
+      end
+    end
   end
 
   describe "#match_existing" do