test: add RSpec specs for RiotApiService

- Test API initialization and configuration
- Add specs for summoner lookup endpoints
- Test error handling (NotFound, RateLimit, Unauthorized)
- Verify region mapping functionality
- Mock external API requests with WebMock

Author: Bulletdev

spec/services/riot_api_service_spec.rb

@@ -0,0 +1,74 @@
+require 'rails_helper'
+
+RSpec.describe RiotApiService do
+  let(:api_key) { 'test-api-key' }
+  let(:service) { described_class.new(api_key: api_key) }
+
+  describe '#initialize' do
+    it 'requires an API key' do
+      expect { described_class.new }.not_to raise_error
+    end
+
+    it 'accepts custom API key' do
+      expect(service.instance_variable_get(:@api_key)).to eq(api_key)
+    end
+  end
+
+  describe '#get_summoner_by_name' do
+    let(:summoner_name) { 'TestPlayer' }
+    let(:region) { 'BR' }
+
+    it 'fetches summoner data' do
+      stub_request(:get, /br1.api.riotgames.com/)
+        .to_return(
+          status: 200,
+          body: {
+            id: 'summoner-id',
+            puuid: 'puuid-123',
+            name: 'TestPlayer',
+            summonerLevel: 150,
+            profileIconId: 4567
+          }.to_json,
+          headers: { 'Content-Type' => 'application/json' }
+        )
+
+      result = service.get_summoner_by_name(summoner_name: summoner_name, region: region)
+
+      expect(result).to include(
+        summoner_id: 'summoner-id',
+        puuid: 'puuid-123',
+        summoner_name: 'TestPlayer'
+      )
+    end
+
+    it 'raises NotFoundError for non-existent summoner' do
+      stub_request(:get, /br1.api.riotgames.com/)
+        .to_return(status: 404)
+
+      expect {
+        service.get_summoner_by_name(summoner_name: summoner_name, region: region)
+      }.to raise_error(RiotApiService::NotFoundError)
+    end
+
+    it 'raises RateLimitError when rate limited' do
+      stub_request(:get, /br1.api.riotgames.com/)
+        .to_return(status: 429, headers: { 'Retry-After' => '120' })
+
+      expect {
+        service.get_summoner_by_name(summoner_name: summoner_name, region: region)
+      }.to raise_error(RiotApiService::RateLimitError)
+    end
+  end
+
+  describe 'region mapping' do
+    it 'maps BR to correct platform' do
+      expect(service.send(:platform_for_region, 'BR')).to eq('BR1')
+    end
+
+    it 'raises error for unknown region' do
+      expect {
+        service.send(:platform_for_region, 'INVALID')
+      }.to raise_error(RiotApiService::RiotApiError, /Unknown region/)
+    end
+  end
+end