exec command - test that format_info_output is actually called in rig…

…ht context

t/command-exec.t

@@ -148,7 +148,21 @@ describe 'exec exit code' => sub {
 Command [perl -E 'somesub 42'] terminated with exit code 7 (\$? = 1792) under the following perl environment:
 format_info_output_value
 OUT
-        }
+        };
+        it "should format info output for right perl" => sub {
+            my $app = App::perlbrew->new(qw(exec --with), "perl-5.14.1", qw(perl -E), "somesub 42");
+            $app->expects("format_info_output")->exactly(1)->returns(sub {
+                my ($self) = @_;
+                is $self->current_env, 'perl-5.14.1';
+                like $self->current_perl_executable, qr/perl-5.14.1/;
+                "format_info_output_value\n";
+            });
+            App::perlbrew->expects("do_exit_with_error_code")->exactly(1)->returns(sub {
+                die "simulate exit\n";
+            });
+            $app->expects("do_system_with_exit_code")->exactly(1)->returns(7<<8);
+            eval { $app->run; 1; };
+        };
     };
     describe "no halt-on-error" => sub {
         it "should exit with success code when several perls ran" => sub {