Testsuite driver: fix encoding issue when calling ghc-pkg

Summary:
In Python 3, subprocess.communicate() returns a pair of bytes, which
need to be decoded. In runtests.py, we were just calling str() instead,
which converts b'x' to "b'x'". As a result, the loop that was checking
pkginfo for lines starting with 'library-dirs' couldn't work.

Reviewers: bgamari, thomie, Phyx

Reviewed By: thomie

Subscribers: Phyx, rwbarton, carter

Differential Revision: https://phabricator.haskell.org/D5046

1 files changed, 2 insertions, 3 deletions

diff --git a/testsuite/driver/testutil.py b/testsuite/driver/testutil.py
index 104bbffab4..15587e6960 100644
--- a/testsuite/driver/testutil.py
+++ b/testsuite/driver/testutil.py
@@ -10,8 +10,7 @@ def strip_quotes(s):
     return s.strip('\'"')
 
 def getStdout(cmd_and_args):
-    # Can't use subprocess.check_output as it's not available in Python 2.6;
-    # It's also not quite the same as check_output, since we also verify that
+    # Can't use subprocess.check_output, since we also verify that
     # no stderr was produced
     p = subprocess.Popen([strip_quotes(cmd_and_args[0])] + cmd_and_args[1:],
                          stdout=subprocess.PIPE,
@@ -22,7 +21,7 @@ def getStdout(cmd_and_args):
         raise Exception("Command failed: " + str(cmd_and_args))
     if stderr:
         raise Exception("stderr from command: %s\nOutput:\n%s\n" % (cmd_and_args, stderr))
-    return stdout
+    return stdout.decode('utf-8')
 
 def lndir(srcdir, dstdir):
     # Create symlinks for all files in src directory.