Merge pull request #42 from GrantBirki/copilot/fix-41

Add comprehensive test suite and improve code maintainability 🧪

Author: GrantBirki

__tests__/fixtures/empty.diff

@@ -0,0 +1 @@
+# Empty diff file for testing

__tests__/fixtures/large.diff

@@ -0,0 +1,7 @@
+diff --git a/old-file.txt b/new-file.txt
+similarity index 100%
+rename from old-file.txt
+rename to new-file.txt
+diff --git a/script.sh b/script.sh
+old mode 100644
+new mode 100755

__tests__/fixtures/rename-and-mode.diff

@@ -0,0 +1,9 @@
+diff --git a/test-file-with-special-chars.txt b/test-file-with-special-chars.txt
+new file mode 100644
+index 0000000..abc123
+--- /dev/null
++++ b/test-file-with-special-chars.txt
+@@ -0,0 +1,3 @@
++This file contains special characters: éñ√ßπ∆
++Unicode: 🚀 🎉 💻
++Symbols: !@#$%^&*()[]{}|;':\",./<>?