...
$file = File->new('t/file7.test');

eval {
    # declare as local so default is restored on block exit
    local *CORE::GLOBAL::read = sub (*\$$;$) { return undef };

    $file->header();
};
...

##</code><code>##

...
sub header {
    my ( $self ) = @_;

    my $seek_rc = $self->{FH}->seek($self->{Header}->{OFFSET}, SEEK_SET );

    if ($seek_rc == 0) {
	croak( 'Cannot seek to absolute file position on opened file handle - ', $! );
    }

    my $length = $self->{FH}->read(my $header, $self->{Header}->{Length});

    # check if read() had an error
    croak( "Error in reading file header - $!") # pathological test
      unless defined $length;

    croak( 'Error in reading file header - Mismatch between expected length (', $self->{Header}->{Length}, ") and returned  length ($length) byte count")
      unless $length == $self->{Header}->{_Length};

    $header =~ s/(?:\015+)?\012.*$/\n/;   # remove any garbage at end of header and replace with \n

    return $header;
}
...