Here's how you obtain the handles with the same methods you use for setting them: 
my $b = Test::More->builder;
binmode STDOUT, $b->failure_output, ':utf8';

[download]
# both of the following are too late for Test::More
# because it has already duplicated STDOUT, STDERR

[download]

That's not quite the cause. If it where, the following would work: 

BEGIN {
   binmode STDOUT, ':utf8';
   binmode STDERR, ':utf8';
}
use Test::More;

[download]
however, it doesn't work for me.

still for a general-purpose module I wouldn't assume that the terminal necessarily accepts UTF-8.

In reply to Re^3: How can I enable utf8 layer on Test::More diag output by moritz
in thread How can I enable utf8 layer on Test::More diag output by mje

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