Configure xctest build settings to prevent Xcode from linking objects.

tools/gn/xcode_writer.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "tools/gn/xcode_writer.h"
 
 #include <iomanip>
 #include <map>
 #include <memory>
 #include <sstream>
@@ skipping 414 matching lines @@
 
         main_project->AddNativeTarget(
             target->label().name(), "compiled.mach-o.executable",
             target->output_name().empty() ? target->label().name()
                                           : target->output_name(),
             "com.apple.product-type.tool",
             GetBuildScript(target->label().name(), ninja_extra_args,
                            env.get()));
         break;
 
-      case Target::CREATE_BUNDLE:
+      case Target::CREATE_BUNDLE: {
         if (target->bundle_data().product_type().empty())
           continue;
 
+        // Test files need to be known to Xcode for proper indexing and for
+        // discovery of tests function for XCTest, but the compilation is done
+        // via ninja and thus must prevent Xcode from linking object files via
+        // this hack.
+        PBXAttributes extra_attributes;
+        if (IsXCTestModuleTarget(target)) {
+          extra_attributes["OTHER_LDFLAGS"] = "-help";
+          extra_attributes["ONLY_ACTIVE_ARCH"] = "YES";
+          extra_attributes["DEBUG_INFORMATION_FORMAT"] = "dwarf";
+        }
+
         main_project->AddNativeTarget(
             target->label().name(), std::string(),
             RebasePath(target->bundle_data()
                            .GetBundleRootDirOutput(target->settings())
                            .value(),
                        build_settings->build_dir()),
             target->bundle_data().product_type(),
-            GetBuildScript(target->label().name(), ninja_extra_args,
-                           env.get()));
+            GetBuildScript(target->label().name(), ninja_extra_args, env.get()),
+            extra_attributes);
         break;
+      }
 
       default:
         break;
     }
   }
 
   projects_.push_back(std::move(main_project));
 }
 
 void XcodeWriter::CreateSourcesProject(
@@ skipping 102 matching lines @@
     for (auto* object : pair.second) {
       object->Print(out, 2);
     }
     out << "/* End " << ToString(pair.first) << " section */\n";
   }
 
   out << "\t};\n"
       << "\trootObject = " << project->Reference() << ";\n"
       << "}\n";
 }