Extract RSpec matcher and make test more robust

Introduce shared matcher for Snowplow tracking

spec/requests/groups/email_campaigns_controller_spec.rb

@@ -12,6 +12,15 @@ RSpec.describe Groups::EmailCampaignsController do
     let_it_be(:user) { create(:user) }
     let(:track) { 'create' }
     let(:series) { '0' }
+    let(:schema) { described_class::EMAIL_CAMPAIGNS_SCHEMA_URL }
+    let(:data) do
+      {
+        namespace_id: group.id,
+        track: track.to_sym,
+        series: series.to_i,
+        subject_line: subject_line(track.to_sym, series.to_i)
+      }
+    end
 
     before do
       sign_in(user)
@@ -19,72 +28,58 @@ RSpec.describe Groups::EmailCampaignsController do
       allow(Gitlab::Tracking).to receive(:self_describing_event)
     end
 
-    subject(:get_index) do
+    subject do
       get group_email_campaigns_url(group, track: track, series: series)
       response
     end
 
-    RSpec::Matchers.define :track_event do |*args|
-      match do
-        expect(Gitlab::Tracking).to have_received(:self_describing_event).with(
-          described_class::EMAIL_CAMPAIGNS_SCHEMA_URL,
-          data: {
-            namespace_id: group.id,
-            track: track.to_sym,
-            series: series.to_i,
-            subject_line: subject_line(track.to_sym, series.to_i)
-          }
-        )
+    shared_examples 'track and redirect' do
+      it do
+        is_expected.to track_self_describing_event(schema, data)
+        is_expected.to have_gitlab_http_status(:redirect)
+      end
     end
 
-      match_when_negated do
-        expect(Gitlab::Tracking).not_to have_received(:self_describing_event)
+    shared_examples 'no track and 404' do
+      it do
+        is_expected.not_to track_self_describing_event
+        is_expected.to have_gitlab_http_status(:not_found)
       end
     end
 
-    context 'track parameter' do
-      where(:track, :valid) do
-        'create' | true
-        'verify' | true
-        'trial'  | true
-        'team'   | true
-        'xxxx'   | false
-        nil      | false
-      end
+    describe 'track parameter' do
+      context 'when valid' do
+        where(track: Namespaces::InProductMarketingEmailsService::TRACKS.keys)
 
         with_them do
-        it do
-          if valid
-            is_expected.to track_event
-            is_expected.to have_gitlab_http_status(:redirect)
-          else
-            is_expected.not_to track_event
-            is_expected.to have_gitlab_http_status(:not_found)
+          it_behaves_like 'track and redirect'
         end
       end
+
+      context 'when invalid' do
+        where(track: [nil, 'xxxx'])
+
+        with_them do
+          it_behaves_like 'no track and 404'
         end
       end
-
-    context 'series parameter' do
-      where(:series, :valid) do
-        '0'  | true
-        '1'  | true
-        '2'  | true
-        '-1' | false
-        '3'  | false
-        nil  | false
     end
 
+    describe 'series parameter' do
+      context 'when valid' do
+        where(series: (0..Namespaces::InProductMarketingEmailsService::INTERVAL_DAYS.length - 1).to_a)
+
         with_them do
-        it do
-          if valid
-            is_expected.to track_event
-            is_expected.to have_gitlab_http_status(:redirect)
-          else
-            is_expected.not_to track_event
-            is_expected.to have_gitlab_http_status(:not_found)
+          it_behaves_like 'track and redirect'
         end
       end
+
+      context 'when invalid' do
+        where(series: [-1, nil, Namespaces::InProductMarketingEmailsService::INTERVAL_DAYS.length])
+
+        with_them do
+          it_behaves_like 'no track and 404'
+        end
       end
     end
   end

spec/support/matchers/track_self_describing_event_matcher.rb

+# frozen_string_literal: true
+
+RSpec::Matchers.define :track_self_describing_event do |schema, data|
+  match do
+    expect(Gitlab::Tracking).to have_received(:self_describing_event)
+      .with(schema, data: data)
+  end
+
+  match_when_negated do
+    expect(Gitlab::Tracking).not_to have_received(:self_describing_event)
+  end
+end