lei_overview: start implementing format detection

We'll need it for IMAP support, at least.  Proper mbox family
detection will be expensive, so deal with it later.

1 files changed, 2 insertions, 0 deletions

diff --git a/t/lei.t b/t/lei.t
index 8bb4e439..64cb5f0e 100644
--- a/t/lei.t
+++ b/t/lei.t
@@ -232,6 +232,8 @@ my $test_external = sub {
                 my @res = $cat->();
                 is_deeply(\@res, [], "clobber w/o --augment $sfx");
         }
+        ok(!$lei->('q', '-o', "$home/mbox", 's:nope'),
+                        'fails if mbox format unspecified');
 };
 
 my $test_lei_common = sub {