Add basic coverage for `TagSearchService` class (#29319)

spec/services/tag_search_service_spec.rb

@@ -0,0 +1,21 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe TagSearchService do
+  describe '#call' do
+    let!(:one) { Fabricate(:tag, name: 'one') }
+
+    before { Fabricate(:tag, name: 'two') }
+
+    it 'runs a search for tags' do
+      results = subject.call('#one', limit: 5)
+
+      expect(results)
+        .to have_attributes(
+          size: 1,
+          first: eq(one)
+        )
+    end
+  end
+end