fix: return explicit message when changes() compares identical versions (#2)

Author: MohammadYusif

graver/core.py

@@ -84,6 +84,9 @@ def changes(self, v1: str | None = None, v2: str | None = None) -> str:
         added = [line for line in result["added"] if line.strip()]
         removed = [line for line in result["removed"] if line.strip()]
 
+        if not added and not removed:
+            return f"No changes between {v1} and {v2}."
+
         lines = [
             f"\n{self.name}  |  {v1} -> {v2}",
             "=" * 55,

tests/test_core.py

@@ -205,3 +205,12 @@ def test_list_all_returns_sorted(tmp_path):
     Prompt("alpha", base_dir=str(tmp_path)).save("content")
     names = Prompt.list_all(base_dir=str(tmp_path))
     assert names == sorted(names)
+
+
+def test_changes_identical_versions_returns_no_changes_message(tmp_path):
+    p = Prompt("system", base_dir=str(tmp_path))
+    same_content = "You are a helpful assistant."
+    p.save(same_content)
+    p.save(same_content)
+    result = p.changes()
+    assert result == "No changes between v1 and v2."