rebaseline.py : add self-tests

tools/rebaseline.py

Index: tools/rebaseline.py
===================================================================
--- tools/rebaseline.py	(revision 9354)
+++ tools/rebaseline.py	(working copy)
@@ -17,7 +17,6 @@
 import os
 import subprocess
 import sys
-import tempfile
 
 # Mapping of gm-expectations subdir (under
 # https://skia.googlecode.com/svn/gm-expected/ )
@@ -76,12 +75,10 @@
             os.path.exists(os.path.join(os.pardir, '.git')))
 
     # Execute subprocess.call(), unless dry_run is True
-    def _Call(self, cmd, stdout=None):
+    def _Call(self, cmd):
         if self._dry_run:
             print '%s' % ' '.join(cmd)
             return 0
-        if stdout:
-            return subprocess.call(cmd, stdout=stdout)
         else:
             return subprocess.call(cmd)
 
@@ -91,14 +88,11 @@
         url = ('http://skia-autogen.googlecode.com/svn/gm-actual/' +
                expectations_subdir + '/' + builder_name + '/' +
                expectations_subdir + '/' + infilename)
-        cmd = [ 'curl', '--fail', '--silent', url ]
-        temp = tempfile.NamedTemporaryFile()

[Stephen White, 2013/05/30 20:34:16]

IIRC, the reason I used a temp file is that if the fetch fails, it'll clobber
the existing result with a 0-length file. I don't think we should do that.

[epoger, 2013/05/31 03:54:06]

Thanks for the explanation... although, if you run curl with --output instead of
piping to stdout, I don't know if that would still happen.  At any rate,
download-and-then-rename seems reasonable.

I have implemented a version of that with deterministic temporary filenames, so
that --dry_run works for the self-test.

-        ret = self._Call(cmd, stdout=temp)
+        cmd = [ 'curl', '--fail', '--silent', url, '--output', outfilename ]
+        ret = self._Call(cmd)
         if ret != 0:
             print '# Couldn\'t fetch ' + url
             return
-        cmd = [ 'cp', temp.name, outfilename ]
-        self._Call(cmd);
         if self._is_svn_checkout:
             cmd = [ 'svn', 'add', '--quiet', outfilename ]
             self._Call(cmd)