@@ 4,24 4,27 @@ import subprocess
 from pathlib import Path
 
 
+def pcall(cmd, args, env=None):
+    try:
+        return subprocess.check_call([cmd] + args, env=env)
+    except OSError:
+        raise OSError('command %r failed, it it in your PATH ?' % cmd)
+
+
 def setup_local_pg_cluster(request, datadir, pgport):
     " create (if missing) a local cluster to use for the tests "
     dbpath = Path(datadir, 'pgdb')
     if not dbpath.exists():
-        subprocess.check_call(['initdb', '-D', dbpath.as_posix(),
-                               '-E', 'utf-8', '--locale=C'])
+        pcall('initdb', ['-D', dbpath.as_posix(), '-E', 'utf-8', '--locale=C'])
     env = os.environ.copy()
     sockdir = tempfile.mkdtemp(prefix='pgsocket')
     options = '-k %s -p %s' % (sockdir, pgport)
     options += ' -c fsync=off -c full_page_writes=off'
     options += ' -c synchronous_commit=off'
-    subprocess.check_call(['pg_ctl', 'start', '-w', '-D', dbpath.as_posix(),
-                           '-o', options],
-                          env=env)
+    pcall('pg_ctl', ['start', '-w', '-D', dbpath.as_posix(), '-o', options], env=env)
 
     def shutdown_postgres():
-        subprocess.call(['pg_ctl', 'stop', '-D', dbpath.as_posix(),
-                         '-m', 'fast'])
+        pcall('pg_ctl', ['stop', '-D', dbpath.as_posix(), '-m', 'fast'])
         try:
             os.rmdir(sockdir)
         except OSError: