Added proper exit-code-checking test for restart issue.

When the process is restarted (and results in an error),
we can now properly check the exit code that comes out of
the 'root' buildout process.

src/zc/buildout/testing.py

@@ -107,7 +107,7 @@ def clean_up_pyc(*path):
 ## FIXME - check for other platforms
 MUST_CLOSE_FDS = not sys.platform.startswith('win')
 
-def system(command, input=''):
+def system(command, input='', with_exit_code=False):
     p = subprocess.Popen(command,
                          shell=True,
                          stdin=subprocess.PIPE,
@@ -121,7 +121,13 @@ def system(command, input=''):
     result = o.read() + e.read()
     o.close()
     e.close()
-    return result.decode()
+    output = result.decode()
+    if with_exit_code:
+        # Use the with_exit_code=True parameter when you want to test the exit
+        # code of the command you're running.
+        p.wait()  # Sets the return code.
+        output += 'EXIT CODE: %s' % p.returncode
+    return output
 
 def get(url):
     return str(urlopen(url).read().decode())

src/zc/buildout/update.txt

@@ -288,32 +288,14 @@ gives us a sys.exit:
     ... recipe = failrecipe
     ... """ % dict(new_releases=new_releases))
 
-Mock the sys.exit:
-
-    >>> import sys
-    >>> orig_exit = sys.exit
-    >>> def sys_exit(code):
-    ...     if code == 'Second exit':
-    ...         print_('Exiting with an error')
-    ...     else:
-    ...         print('Sys.exit with error %s' % code)
-    ...         #raise SystemExit(code)
-    >>> sys.exit = sys_exit
-
 Run the buildout:
 
-    >>> print_(system(buildout), end='')
+    >>> print_(system(buildout, with_exit_code=True), end='')
     Upgraded:
       zc.buildout version 1.4.4;
       distribute version 0.6;
     restarting.
     Generated script '/sample-buildout/bin/buildout'.
     Develop: '/sample-buildout/failrecipe'
-    sys.exit occurred. Exit code: recipe sys-exits
-
-Restore sys.exit:
-
-    >>> sys.exit = orig_exit
-
-    >>> print_("We are still alive")
-    We are still alive
+    recipe sys-exits
+    EXIT CODE: 1