1 files changed, 104 insertions, 0 deletions
diff --git a/vcx_patch.t b/vcx_patch.t
new file mode 100644
index 0000000..d2b813f
--- /dev/null
+++ b/vcx_patch.t
@@ -0,0 +1,104 @@
+#!/usr/bin/perl
+use strict;
+use warnings;
+use Test::More;
+use File::Temp qw(tempfile);
+use File::Spec;
+
+# Overrides exit and silences the 'Usage' print during the 'do' call.
+BEGIN {
+	*CORE::GLOBAL::exit = sub { }; 
+}
+
+{
+	local @ARGV = (); 
+	open my $oldout, ">&STDOUT";
+	open STDOUT, ">", File::Spec->devnull();
+	eval { do './vcx' };
+	open STDOUT, ">&", $oldout;
+}
+
+subtest 'Binary Patching: Shrink & Truncate' => sub {
+	my ($fh_old, $old_path) = tempfile();
+	my ($fh_new, $new_path) = tempfile();
+
+	# 8KB of 'A' shrinking to 6 bytes
+	print $fh_old "A" x 8192; close $fh_old;
+	print $fh_new "SHRINK";   close $fh_new;
+
+	my $patch = main::make_bin_patch($new_path, $old_path);
+	ok(defined($patch), "Patch generated for shrinking file");
+	
+	main::apply_bin_patch($old_path, $patch);
+
+	is(-s $old_path, 6, "File size correctly truncated to 6 bytes");
+	
+	open my $check, '<:raw', $old_path;
+	my $content = <$check>;
+	is($content, "SHRINK", "Content matches perfectly (no stale trailing data)");
+	close $check;
+};
+
+subtest 'Binary Patching: Growth & Extension' => sub {
+	my ($fh_old, $old_path) = tempfile();
+	my ($fh_new, $new_path) = tempfile();
+
+	print $fh_old "Tiny";
+	close $fh_old;
+
+	# Create a 5KB string to cross a block boundary (4096)
+	my $big_data = "EXTENDED" . ("." x 5000);
+	print $fh_new $big_data;
+	close $fh_new;
+
+	my $patch = main::make_bin_patch($new_path, $old_path);
+	main::apply_bin_patch($old_path, $patch);
+
+	is(-s $old_path, 5008, "File size correctly extended");
+	
+	open my $check, '<:raw', $old_path;
+	my $result = do { local $/; <$check> };
+	is($result, $big_data, "Extended content matches perfectly");
+	close $check;
+};
+
+subtest 'Binary Patching: Sparse Block Edits' => sub {
+	my ($fh_old, $old_path) = tempfile();
+	my ($fh_new, $new_path) = tempfile();
+
+	# Create three 4KB blocks
+	my $data = ("X" x 4096) . ("Y" x 4096) . ("Z" x 4096);
+	print $fh_old $data; close $fh_old;
+
+	# Modify only the middle block ('Y' block)
+	substr($data, 5000, 10) = "MODIFIED!!";
+	print $fh_new $data; close $fh_new;
+
+	my $patch = main::make_bin_patch($new_path, $old_path);
+	
+	# Header (8) + Block Header (12) + Block (4096) = ~4116 bytes
+	ok(length($patch) < 4200, "Patch is efficient (only captured the changed block)");
+
+	main::apply_bin_patch($old_path, $patch);
+	
+	open my $check, '<:raw', $old_path;
+	my $final = do { local $/; <$check> };
+	is(substr($final, 5000, 10), "MODIFIED!!", "Middle block update applied");
+	is(substr($final, 0, 10), "XXXXXXXXXX", "First block preserved");
+	is(substr($final, -10), "ZZZZZZZZZZ", "Last block preserved");
+	close $check;
+};
+
+subtest 'Binary Patching: No Change Identity' => sub {
+	my ($fh_old, $old_path) = tempfile();
+	my ($fh_new, $new_path) = tempfile();
+
+	my $data = "Same data" x 50;
+	print $fh_old $data; close $fh_old;
+	print $fh_new $data; close $fh_new;
+
+	my $patch = main::make_bin_patch($new_path, $old_path);
+	is($patch, undef, "No patch generated for identical files");
+};
+
+done_testing();