feat: Add a tool to search Linear Issues in copilot (#11518)

This PR adds a tool to search Linear issues. If the integration is
enabled for the account, the tool will return results as expected. Also
introduces support for an `active?` method, which allows third-party
Copilot tools to be conditionally enabled based on the status of the
integration on the account.

spec/enterprise/services/captain/tools/copilot/search_linear_issues_service_spec.rb

@@ -0,0 +1,125 @@
+require 'rails_helper'
+
+RSpec.describe Captain::Tools::Copilot::SearchLinearIssuesService do
+  let(:account) { create(:account) }
+  let(:assistant) { create(:captain_assistant, account: account) }
+  let(:service) { described_class.new(assistant) }
+
+  describe '#name' do
+    it 'returns the correct service name' do
+      expect(service.name).to eq('search_linear_issues')
+    end
+  end
+
+  describe '#description' do
+    it 'returns the service description' do
+      expect(service.description).to eq('Search Linear issues based on a search term')
+    end
+  end
+
+  describe '#parameters' do
+    it 'returns the expected parameter schema' do
+      expect(service.parameters).to eq(
+        {
+          type: 'object',
+          properties: {
+            term: {
+              type: 'string',
+              description: 'The search term to find Linear issues'
+            }
+          },
+          required: %w[term]
+        }
+      )
+    end
+  end
+
+  describe '#active?' do
+    context 'when Linear integration is enabled' do
+      before do
+        create(:integrations_hook, :linear, account: account)
+      end
+
+      it 'returns true' do
+        expect(service.active?).to be true
+      end
+    end
+
+    context 'when Linear integration is not enabled' do
+      it 'returns false' do
+        expect(service.active?).to be false
+      end
+    end
+  end
+
+  describe '#execute' do
+    context 'when Linear integration is not enabled' do
+      it 'returns error message' do
+        expect(service.execute({ 'term' => 'test' })).to eq('Linear integration is not enabled')
+      end
+    end
+
+    context 'when Linear integration is enabled' do
+      let(:linear_service) { instance_double(Integrations::Linear::ProcessorService) }
+
+      before do
+        create(:integrations_hook, :linear, account: account)
+        allow(Integrations::Linear::ProcessorService).to receive(:new).and_return(linear_service)
+      end
+
+      context 'when term is blank' do
+        it 'returns error message' do
+          expect(service.execute({ 'term' => '' })).to eq('Missing required parameters')
+        end
+      end
+
+      context 'when search returns error' do
+        before do
+          allow(linear_service).to receive(:search_issue).and_return({ error: 'API Error' })
+        end
+
+        it 'returns the error message' do
+          expect(service.execute({ 'term' => 'test' })).to eq('API Error')
+        end
+      end
+
+      context 'when search returns no issues' do
+        before do
+          allow(linear_service).to receive(:search_issue).and_return({ data: [] })
+        end
+
+        it 'returns no issues found message' do
+          expect(service.execute({ 'term' => 'test' })).to eq('No issues found, I should try another similar search term')
+        end
+      end
+
+      context 'when search returns issues' do
+        let(:issues) do
+          [{
+            'title' => 'Test Issue',
+            'id' => 'TEST-123',
+            'state' => { 'name' => 'In Progress' },
+            'priority' => 4,
+            'assignee' => { 'name' => 'John Doe' },
+            'description' => 'Test description'
+          }]
+        end
+
+        before do
+          allow(linear_service).to receive(:search_issue).and_return({ data: issues })
+        end
+
+        it 'returns formatted issues' do
+          result = service.execute({ 'term' => 'test' })
+          expect(result).to include('Total number of issues: 1')
+          expect(result).to include('Title: Test Issue')
+          expect(result).to include('ID: TEST-123')
+          expect(result).to include('State: In Progress')
+          expect(result).to include('Priority: Low')
+          expect(result).to include('Assignee: John Doe')
+          expect(result).to include('Description: Test description')
+        end
+      end
+    end
+  end
+end