diff --git a/tools/gn/ninja_binary_target_writer_unittest.cc b/tools/gn/ninja_binary_target_writer_unittest.cc
index 5fa5639..388c96f 100644
--- a/tools/gn/ninja_binary_target_writer_unittest.cc
+++ b/tools/gn/ninja_binary_target_writer_unittest.cc
@@ -983,10 +983,14 @@
 
   EXPECT_FALSE(scheduler().is_failed());
 
+  scheduler().SuppressOutputForTesting(true);
+
   std::ostringstream out;
   NinjaBinaryTargetWriter writer(&target, out);
   writer.Run();
 
+  scheduler().SuppressOutputForTesting(false);
+
   // Should have issued an error.
   EXPECT_TRUE(scheduler().is_failed());
 }
diff --git a/tools/gn/scheduler.cc b/tools/gn/scheduler.cc
index cf66dc7..0feb4a1 100644
--- a/tools/gn/scheduler.cc
+++ b/tools/gn/scheduler.cc
@@ -21,6 +21,7 @@
       verbose_logging_(false),
       pool_work_count_cv_(&pool_work_count_lock_),
       is_failed_(false),
+      suppress_output_for_testing_(false),
       has_been_shutdown_(false) {
   g_scheduler = this;
 }
@@ -166,6 +167,11 @@
   }
 }
 
+void Scheduler::SuppressOutputForTesting(bool suppress) {
+  base::AutoLock lock(lock_);
+  suppress_output_for_testing_ = suppress;
+}
+
 void Scheduler::LogOnMainThread(const std::string& verb,
                                 const std::string& msg) {
   OutputString(verb, DECORATION_YELLOW);
@@ -173,7 +179,8 @@
 }
 
 void Scheduler::FailWithErrorOnMainThread(const Err& err) {
-  err.PrintToStdout();
+  if (!suppress_output_for_testing_)
+    err.PrintToStdout();
   runner_.Quit();
 }
 
diff --git a/tools/gn/scheduler.h b/tools/gn/scheduler.h
index 02c1d8a..447551e 100644
--- a/tools/gn/scheduler.h
+++ b/tools/gn/scheduler.h
@@ -90,6 +90,8 @@
   void IncrementWorkCount();
   void DecrementWorkCount();
 
+  void SuppressOutputForTesting(bool suppress);
+
  private:
   void LogOnMainThread(const std::string& verb, const std::string& msg);
   void FailWithErrorOnMainThread(const Err& err);
@@ -127,6 +129,8 @@
   mutable base::Lock lock_;
   bool is_failed_;
 
+  bool suppress_output_for_testing_;
+
   // Used to track whether the worker pool has been shutdown. This is necessary
   // to clean up after tests that make a scheduler but don't run the message
   // loop.
diff --git a/tools/gn/string_utils_unittest.cc b/tools/gn/string_utils_unittest.cc
index 372e227..77d8f42 100644
--- a/tools/gn/string_utils_unittest.cc
+++ b/tools/gn/string_utils_unittest.cc
@@ -54,7 +54,6 @@
 
   if (!success)
     return true;  // Don't check result on failure.
-  printf("%s\n", result.string_value().c_str());
   return result.string_value() == expected;
 }