fix: return true from BINMODE on mocked filehandles

lib/Test/MockFile/FileHandle.pm

@@ -556,7 +556,7 @@ exists on this method.
 
 sub BINMODE {
     my ($self) = @_;
-    return;
+    return 1;
 }
 
 =head2 OPEN

t/binmode.t

@@ -0,0 +1,42 @@
+#!/usr/bin/perl -w
+
+use strict;
+use warnings;
+
+use Test2::Bundle::Extended;
+use Test2::Tools::Explain;
+use Test2::Plugin::NoWarnings;
+
+use Test::MockFile ();
+
+subtest 'binmode returns true on mocked filehandle' => sub {
+    my $mock = Test::MockFile->file( '/tmp/binmode_test', "hello world" );
+
+    open my $fh, '<', '/tmp/binmode_test' or die "open: $!";
+    my $ret = binmode($fh);
+    ok( $ret, 'binmode() returns a true value on mocked filehandle' );
+    close $fh;
+};
+
+subtest 'binmode with encoding layer returns true' => sub {
+    my $mock = Test::MockFile->file( '/tmp/binmode_enc', "hello world" );
+
+    open my $fh, '<', '/tmp/binmode_enc' or die "open: $!";
+    my $ret = binmode( $fh, ':utf8' );
+    ok( $ret, 'binmode($fh, ":utf8") returns a true value on mocked filehandle' );
+    close $fh;
+};
+
+subtest 'binmode or die pattern works' => sub {
+    my $mock = Test::MockFile->file( '/tmp/binmode_die', "content" );
+
+    open my $fh, '<', '/tmp/binmode_die' or die "open: $!";
+    my $lived = eval {
+        binmode($fh) or die "binmode failed: $!";
+        1;
+    };
+    ok( $lived, 'binmode($fh) or die does not die on mocked filehandle' );
+    close $fh;
+};
+
+done_testing();