[trainer] check specifically for file url in failure_message, fixing crash in Xcode 15 when running in Apple Silicon

trainer/lib/trainer/xcresult.rb

@@ -391,7 +391,7 @@ def initialize(data)
 
       def failure_message
         new_message = self.message
-        if self.document_location_in_creating_workspace
+        if self.document_location_in_creating_workspace&.url
           file_path = self.document_location_in_creating_workspace.url.gsub("file://", "")
           new_message += " (#{file_path})"
         end

trainer/spec/test_parser_spec.rb

@@ -198,6 +198,15 @@
                                 }
                               ])
       end
+
+      it "still produces a test failure message when file url is missing", requires_xcode: true do
+        allow_any_instance_of(Trainer::XCResult::TestFailureIssueSummary).to receive(:document_location_in_creating_workspace).and_return(nil)
+        tp = Trainer::TestParser.new("./trainer/spec/fixtures/Test.test_result.xcresult")
+        test_failures = tp.data.last[:tests].select { |t| t[:failures] }
+        failure_messages = test_failures.map { |tf| tf[:failures].first[:failure_message] }
+        expect(failure_messages).to eq(["XCTAssertTrue failed", "XCTAssertTrue failed"])
+        RSpec::Mocks.space.proxy_for(Trainer::XCResult::TestFailureIssueSummary).reset
+      end
     end
   end
 end