[test] Correctly deduce test-driver arguments on bots using GN

tools/run-tests.py

Index: tools/run-tests.py
diff --git a/tools/run-tests.py b/tools/run-tests.py
index 84fbfc18883556ce644ec6f2118067bcdfe756f5..e0e44aa5595dbe4e6d241460d1fbe3bb72cd74d5 100755
--- a/tools/run-tests.py
+++ b/tools/run-tests.py
@@ -452,8 +452,13 @@ def ProcessOptions(options):
       print(">>> Latest GN build found is %s" % latest_config)
       options.outdir = os.path.join(DEFAULT_OUT_GN, latest_config)
 
-  build_config_path = os.path.join(
-      BASE_DIR, options.outdir, "v8_build_config.json")
+  if options.buildbot:
+    build_config_path = os.path.join(
+        BASE_DIR, options.outdir, options.mode, "v8_build_config.json")

[Michael Achenbach, 2016/10/18 14:05:37]

It is a convention on buildbot that the build products are in outdir + mode,
e.g. out/Release.

+  else:
+    build_config_path = os.path.join(
+        BASE_DIR, options.outdir, "v8_build_config.json")
+
   if os.path.exists(build_config_path):
     try:
       with open(build_config_path) as f:
@@ -464,6 +469,10 @@ def ProcessOptions(options):
       return False
     options.auto_detect = True
 
+    # In auto-detect mode the outdir is always where we found the build config.
+    # This ensures that we'll also take the build products from there.
+    options.outdir = os.path.dirname(build_config_path)
+
     options.arch_and_mode = None
     options.arch = build_config["v8_target_cpu"]
     if options.arch == 'x86':
@@ -711,15 +720,15 @@ def Execute(arch, mode, args, options, suites):
 
   shell_dir = options.shell_dir
   if not shell_dir:
-    if options.buildbot:
+    if options.auto_detect:
+      # If an output dir with a build was passed, test directly in that
+      # directory.
+      shell_dir = os.path.join(BASE_DIR, options.outdir)
+    elif options.buildbot:

[Michael Achenbach, 2016/10/18 14:05:37]

This remains for gyp bots that don't support auto-detect.

       # TODO(machenbach): Get rid of different output folder location on
       # buildbot. Currently this is capitalized Release and Debug.
       shell_dir = os.path.join(BASE_DIR, options.outdir, mode)
       mode = BuildbotToV8Mode(mode)
-    elif options.auto_detect:
-      # If an output dir with a build was passed, test directly in that
-      # directory.
-      shell_dir = os.path.join(BASE_DIR, options.outdir)
     else:
       shell_dir = os.path.join(
           BASE_DIR,