Fix command parser: resizing tiling windows

i3 would accept an invalid resize command like 'resize shrink width 10
px or' without specifying the ppt value, and then crash. This patch
fixes the parser specification.

testcases/t/187-commands-parser.t

@@ -171,4 +171,19 @@ is(parser_calls('workspace "foo \"bar"'),
    'cmd_workspace_name(foo "bar)',
    'Command with escaped double quotes ok');
 
+################################################################################
+# 4: Verify that resize commands with a "px or ppt"-construction are parsed
+# correctly
+################################################################################
+
+is(parser_calls("resize shrink width 10 px or"),
+   "ERROR: Expected one of these tokens: <word>\n" .
+   "ERROR: Your command: resize shrink width 10 px or\n" .
+   "ERROR:                                           ",
+   "error for resize command with incomplete 'or'-construction ok");
+
+is(parser_calls("resize grow left 10 px or 20 ppt"),
+   "cmd_resize(grow, left, 10, 20)",
+   "resize command with 'or'-construction ok");
+
 done_testing;