When running iOS tests on devices, write stdout to a file, then dump to NSLog.

base/test/test_support_ios.mm

 // Copyright (c) 2012 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.
 
 #import <UIKit/UIKit.h>
 
 #include "base/debug/debugger.h"
 #include "base/logging.h"
 #include "base/mac/scoped_nsautorelease_pool.h"
 #include "base/memory/scoped_nsobject.h"
@@ skipping 40 matching lines @@
   // Yes, this is leaked, it's just to make what's running visible.
   window_.reset([[UIWindow alloc] initWithFrame:bounds]);
   [window_ makeKeyAndVisible];
 
   // Add a label with the app name.
   UILabel* label = [[[UILabel alloc] initWithFrame:bounds] autorelease];
   label.text = [[NSProcessInfo processInfo] processName];
   label.textAlignment = UITextAlignmentCenter;
   [window_ addSubview:label];
 
+  if ([self shouldRedirectOutputToFile])
+    [self redirectOutput];
+
   // Queue up the test run.
   [self performSelector:@selector(runTests)
              withObject:nil
              afterDelay:0.1];
   return YES;
 }
 
+// Returns true if the gtest output should be redirected to a file, then sent
+// to NSLog when compleete. This redirection is used because gtest only writes
+// output to stdout, but results must be written to NSLog in order to show up in
+// the device log that is retrieved from the device by the host.
+- (BOOL)shouldRedirectOutputToFile {
+#if !TARGET_IPHONE_SIMULATOR
+  return !base::debug::BeingDebugged();
+#endif  // TARGET_IPHONE_SIMULATOR
+  return NO;
+}
+
+// Returns the path to the directory to store gtest output files.
+- (NSString*)outputPath {
+  NSArray* searchPath =
+      NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,
+                                          NSUserDomainMask,
+                                          YES);
+  CHECK([searchPath count] > 0) << "Failed to get the Documents folder";
+  return [searchPath objectAtIndex:0];
+}
+
+// Returns the path to file that stdout is redirected to.
+- (NSString*)stdoutPath {
+  return [[self outputPath] stringByAppendingPathComponent:@"stdout.log"];
+}
+
+// Returns the path to file that stderr is redirected to.
+- (NSString*)stderrPath {
+  return [[self outputPath] stringByAppendingPathComponent:@"stderr.log"];
+}
+
+// Redirects stdout and stderr to files in the Documents folder in the app's
+// sandbox.
+- (void)redirectOutput {
+  freopen([[self stdoutPath] UTF8String], "w+", stdout);
+  freopen([[self stderrPath] UTF8String], "w+", stderr);
+}
+
+// Reads the redirected gtest output from a file and writes it to NSLog.
+- (void)writeOutputToNSLog {
+  for (NSString* path in @[ [self stdoutPath], [self stderrPath]]) {
+    NSString* content = [NSString stringWithContentsOfFile:path
+                                                  encoding:NSUTF8StringEncoding
+                                                     error:NULL];
+    NSArray* lines = [content componentsSeparatedByCharactersInSet:
+        [NSCharacterSet newlineCharacterSet]];
+
+    NSLog(@"Writing contents of %@ to NSLog", path);
+    for (NSString* line in lines) {
+      NSLog(@"%@", line);
+    }
+  }
+}
+
 - (void)runTests {
   int exitStatus = g_test_suite->Run();
 
+  if ([self shouldRedirectOutputToFile])
+    [self writeOutputToNSLog];
+
   // If a test app is too fast, it will exit before Instruments has has a
   // a chance to initialize and no test results will be seen.
   // TODO(ios): crbug.com/137010 Figure out how much time is actually needed,
   // and sleep only to make sure that much time has elapsed since launch.
   [NSThread sleepUntilDate:[NSDate dateWithTimeIntervalSinceNow:2.0]];
   window_.reset();
 
   // Use the hidden selector to try and cleanly take down the app (otherwise
   // things can think the app crashed even on a zero exit status).
   UIApplication* application = [UIApplication sharedApplication];
@@ skipping 38 matching lines @@
   if (!ran_hook) {
     ran_hook = true;
     mac::ScopedNSAutoreleasePool pool;
     int exit_status = UIApplicationMain(g_argc, g_argv, nil,
                                         @"ChromeUnitTestDelegate");
     exit(exit_status);
   }
 }
 
 }  // namespace base