Test::Mojo + prove leads to duplicate logging - perl

Question

I have the following test script that utilizes Test::Mojo. When I run it from the command line using perl, it outputs correctly. However, when I run it through "prove -v", the Mojo logging is duplicated and one of them isn't piped through "on message".
#!/usr/bin/env perl
use strict;
use warnings;
use Test::More tests => 1;
use Mojolicious::Lite;
use Test::Mojo;
app->log->on(
message => sub {
my ( $log, $level, #lines ) = #_;
note "MojoLog $level: #lines";
}
);
get '/debug/mojo/req_url' => sub {
my $c = shift;
$c->render( text => $c->req->url );
};
subtest 'Mojo - $c->req->url' => sub {
plan tests => 3;
my $t = Test::Mojo->new;
$t->get_ok('/debug/mojo/req_url') #
->status_is(200) #
->content_is('/debug/mojo/req_url');
};
The output when run directly:
$ perl dup_logging.t
1..1
# Subtest: Mojo - $c->req->url
1..3
# MojoLog debug: GET "/debug/mojo/req_url"
# MojoLog debug: Routing to a callback
# MojoLog debug: 200 OK (0.000797s, 1254.705/s)
ok 1 - GET /debug/mojo/req_url
ok 2 - 200 OK
ok 3 - exact match for content
ok 1 - Mojo - $c->req->url
And the output when run through prove:
$ prove -v dup_logging.t
dup_logging.t ..
1..1
# Subtest: Mojo - $c->req->url
1..3
[Thu Mar 8 12:16:35 2018] [debug] GET "/debug/mojo/req_url"
# MojoLog debug: GET "/debug/mojo/req_url"
[Thu Mar 8 12:16:35 2018] [debug] Routing to a callback
# MojoLog debug: Routing to a callback
[Thu Mar 8 12:16:35 2018] [debug] 200 OK (0.000842s, 1187.648/s)
# MojoLog debug: 200 OK (0.000842s, 1187.648/s)
ok 1 - GET /debug/mojo/req_url
ok 2 - 200 OK
ok 3 - exact match for content
ok 1 - Mojo - $c->req->url
ok
All tests successful.
Files=1, Tests=1, 1 wallclock secs ( 0.03 usr 0.01 sys + 0.34 cusr 0.03 csys = 0.41 CPU)
Result: PASS
The following is my version information:
$ perl -MMojolicious -E 'say Mojolicious->VERSION'
7.14
$ prove --version
TAP::Harness v3.36 and Perl v5.16.3
I discovered that one way to avoid this problem is to set the MOJO_LOG_LEVEL environment variable at the top of the script.
$ENV{MOJO_LOG_LEVEL} = 'fatal';
Any other suggestions on how to get prove and Test::Mojo to play well together with regard to the logging?

Answer 1

The prove testrunner uses the TAP::Harness infrastructure. When you run prove -v, this will set the HARNESS_IS_VERBOSE environment variable.
Then, Mojo::Test picks up this environment variable:
# Silent or loud tests
$ENV{MOJO_LOG_LEVEL} ||= $ENV{HARNESS_IS_VERBOSE} ? 'debug' : 'fatal';
You therefore get Mojo's debug log messages when running prove -v.
It seems that manually setting the MOJO_LOG_LEVEL env variable is the best approach if you do not want this output.