NAME

Test::HexString - test binary strings with hex dump diagnostics

SYNOPSIS

use Test::More tests => 1;
use Test::HexString;

my $data = generate_some_output;

is_hexstr( $data, "\x01\x02\x03\x04", 'Generated output' );

DESCRIPTION

This testing module provides a single function, is_hexstr(), which asserts that the given string matches what was expected. When the strings match (i.e. compare equal using the eq operator), the behaviour is identical to the usual is() function provided by Test::More.

When the strings are different, a hex dump is produced as diagnostic, rather than the string values being printed raw. This may be beneficial if the string contains largely binary data, such as may be produced by binary file or network protocol modules.

To print the hex dump when it fails, each string is broken into 16 byte chunks. The first pair of chunks that fail to match are then printed, in both hexadecimal and character form, in a message in the following format:

#   Failed test at -e line 1.
#   at bytes 0-0xf (0-15)
#   got: | 61 20 6c 6f 6e 67 20 73 74 72 69 6e 67 20 68 65 |a long string he|
#   exp: | 61 20 6c 6f 6e 67 20 53 74 72 69 6e 67 20 68 65 |a long String he|
# Looks like you failed 1 test of 1.

Only bytes in the range 0x20-0x7e are printed as literal characters. Any other byte is rendered as .:

#   Failed test at -e line 1.
#   at bytes 0-0xf (0-15)
#   got: | 00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f |................|
#   exp: | 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f 10 |................|
# Looks like you failed 1 test of 1.

Only the first differing line is printed; because otherwise it may result in a long output because of misaligned bytes.

If STDOUT is a terminal, then different bytes are printed in bold for visibility.

FUNCTIONS

is_hexstr( $got, $expect, $name )

Test that the string $got is what was expected by $expect. If the strings are not equal, a hex dump is printed showing the region where they first start to differ.

AUTHOR

Paul Evans <leonerd@leonerd.org.uk>