Add specs for callback_url + fixes

lib/omniauth/strategies/pagerduty.rb

@@ -42,7 +42,7 @@ def me
       end
 
       def callback_url
-        full_host + script_name + callback_path
+        options.redirect_url || (full_host + callback_path)
       end
     end
   end

spec/omniauth/strategies/pagerduty_spec.rb

@@ -57,11 +57,24 @@
   end
 
   describe '#callback_url' do
-    it 'is a combination of host, script name, and callback path' do
-      allow(subject).to receive(:full_host).and_return('https://example.com')
-      allow(subject).to receive(:script_name).and_return('/sub_uri')
+    let(:base_url) { 'https://example.com' }
 
-      expect(subject.callback_url).to eq('https://example.com/sub_uri/auth/pagerduty/callback')
+    context 'no script name present' do
+      it 'has the correct default callback path' do
+        allow(subject).to receive(:full_host) { base_url }
+        allow(subject).to receive(:script_name) { '' }
+        allow(subject).to receive(:query_string) { '' }
+        expect(subject.callback_url).to eq(base_url + '/auth/pagerduty/callback')
+      end
+    end
+
+    context 'script name' do
+      it 'should set the callback path with script_name' do
+        allow(subject).to receive(:full_host) { base_url }
+        allow(subject).to receive(:script_name) { '/v1' }
+        allow(subject).to receive(:query_string) { '' }
+        expect(subject.callback_url).to eq(base_url + '/v1/auth/pagerduty/callback')
+      end
     end
   end
 end