test: add unit tests for TestFiles.add() deduplication

Author: KRRT7

tests/test_test_files_add.py

@@ -0,0 +1,46 @@
+from pathlib import Path
+
+import pytest
+
+from codeflash.models.models import TestFile, TestFiles
+from codeflash.models.test_type import TestType
+
+
+class TestTestFilesAdd:
+    def test_add_unique_test_file(self) -> None:
+        tf = TestFiles(test_files=[])
+        test_file = TestFile(
+            instrumented_behavior_file_path=Path("/tmp/test_behavior.py"),
+            benchmarking_file_path=Path("/tmp/test_perf.py"),
+            test_type=TestType.GENERATED_REGRESSION,
+        )
+        tf.add(test_file)
+        assert len(tf.test_files) == 1
+        assert tf.test_files[0] is test_file
+
+    def test_add_duplicate_raises(self) -> None:
+        tf = TestFiles(test_files=[])
+        test_file = TestFile(
+            instrumented_behavior_file_path=Path("/tmp/test_behavior.py"),
+            benchmarking_file_path=Path("/tmp/test_perf.py"),
+            test_type=TestType.GENERATED_REGRESSION,
+        )
+        tf.add(test_file)
+        with pytest.raises(ValueError, match="Test file already exists"):
+            tf.add(test_file)
+
+    def test_add_many_files_performance(self) -> None:
+        tf = TestFiles(test_files=[])
+        for i in range(100):
+            test_file = TestFile(
+                instrumented_behavior_file_path=Path(f"/tmp/test_behavior_{i}.py"),
+                benchmarking_file_path=Path(f"/tmp/test_perf_{i}.py"),
+                test_type=TestType.GENERATED_REGRESSION,
+            )
+            tf.add(test_file)
+
+        assert len(tf.test_files) == 100
+        assert len(tf._seen_paths) == 100
+        # Verify all paths are unique in the set
+        expected_paths = {Path(f"/tmp/test_behavior_{i}.py") for i in range(100)}
+        assert tf._seen_paths == expected_paths