+# not a method
+sub _show_diff {
+ my $SNIPPET_SIZE = 10;
+
+ my ($expected, $actual) = @_;
+
+ my $str = '';
+ my $explen = length $expected;
+ my $actlen = length $actual;
+
+ if ($explen != $actlen) {
+ $str .= "Sizes don't match: expected = $explen, actual = $actlen\n";
+ }
+
+ my $min = $explen <= $actlen? $explen : $actlen;
+ my $line = 1;
+ my $col = 1;
+ my $i;
+ for ($i=0; $i != $min; ++$i) {
+ last if substr($expected, $i, 1) ne substr($actual, $i, 1);
+ if (substr($expected, $i, 1) eq '\n') {
+ $line++;
+ $col = 0;
+ } else {
+ $col++;
+ }
+ }
+ my $snip_start = $i - ($SNIPPET_SIZE / 2);
+ if ($snip_start < 0) {
+ $SNIPPET_SIZE += $snip_start; # Take it from the end.
+ $snip_start = 0;
+ }
+ my $exp_snip = substr($expected, $snip_start, $SNIPPET_SIZE);
+ my $act_snip = substr($actual, $snip_start, $SNIPPET_SIZE);
+ $exp_snip =~s/[^[:print:]]/ quotechar($&) /ge;
+ $act_snip =~s/[^[:print:]]/ quotechar($&) /ge;
+ $str .= "Mismatch at line $line, col $col:\n";
+ $str .= " $exp_snip\n";
+ $str .= " $act_snip\n";
+
+ return $str;
+}