fix: resolve BitNet perplexity defaults from the script dir

tests/test_test_perplexity_paths.py

@@ -0,0 +1,83 @@
+import importlib.util
+import tempfile
+import unittest
+from pathlib import Path
+
+
+MODULE_PATH = Path(__file__).resolve().parents[1] / "utils" / "test_perplexity.py"
+
+
+def load_test_perplexity_module():
+    spec = importlib.util.spec_from_file_location(
+        "bitnet_test_perplexity_under_test", MODULE_PATH
+    )
+    if spec is None or spec.loader is None:
+        raise RuntimeError(f"Unable to load {MODULE_PATH}")
+    module = importlib.util.module_from_spec(spec)
+    spec.loader.exec_module(module)
+    return module
+
+
+class TestPerplexityPathTests(unittest.TestCase):
+    def test_resolve_default_path_uses_script_dir_for_built_in_defaults(self):
+        module = load_test_perplexity_module()
+
+        resolved = module.resolve_default_path(
+            "../build/bin/llama-perplexity", "../build/bin/llama-perplexity"
+        )
+
+        self.assertEqual(
+            resolved, (MODULE_PATH.parent / "../build/bin/llama-perplexity").resolve()
+        )
+
+    def test_resolve_default_path_keeps_custom_paths(self):
+        module = load_test_perplexity_module()
+
+        self.assertEqual(
+            module.resolve_default_path(
+                "/tmp/custom-bin", "../build/bin/llama-perplexity"
+            ),
+            Path("/tmp/custom-bin"),
+        )
+        self.assertEqual(
+            module.resolve_default_path(
+                "models/custom.gguf", "../build/bin/llama-perplexity"
+            ),
+            Path("models/custom.gguf"),
+        )
+
+    def test_perplexity_tester_uses_resolved_default_paths(self):
+        module = load_test_perplexity_module()
+
+        with tempfile.TemporaryDirectory() as tmp:
+            model_path = Path(tmp) / "model.gguf"
+            model_path.write_text("stub")
+
+            expected_bin = (
+                MODULE_PATH.parent / "../build/bin/llama-perplexity"
+            ).resolve()
+            expected_quant = (
+                MODULE_PATH.parent / "../build/bin/llama-quantize"
+            ).resolve()
+            expected_data = (MODULE_PATH.parent / "../data").resolve()
+
+            original_exists = module.Path.exists
+
+            def fake_exists(self):
+                if self in {expected_bin, expected_quant, expected_data, model_path}:
+                    return True
+                return original_exists(self)
+
+            module.Path.exists = fake_exists
+            try:
+                tester = module.PerplexityTester(str(model_path))
+            finally:
+                module.Path.exists = original_exists
+
+            self.assertEqual(tester.llama_perplexity_bin, expected_bin)
+            self.assertEqual(tester.quantize_bin, expected_quant)
+            self.assertEqual(tester.data_dir, expected_data)
+
+
+if __name__ == "__main__":
+    unittest.main()