Update test to include PYTHONPATH environment variable

Author: Kiguli

tests/test_main.py

@@ -5,20 +5,21 @@
 def test_benchmark_runs():
     """Check that the benchmark script runs without errors."""
 
-    # Path to the benchmark script (update if needed)
     benchmark_path = os.path.join(
         os.path.dirname(__file__),
         "..", "ex", "benchmarks-deterministic", "PRoTECT-versions", "ex1_dt_DS.py"
     )
 
-    # Verify the file exists before running
     assert os.path.exists(benchmark_path), f"Benchmark script not found: {benchmark_path}"
 
+    env = os.environ.copy()
+    env["PYTHONPATH"] = os.path.join(os.path.dirname(__file__), "..")
+
     result = subprocess.run(
         [sys.executable, benchmark_path],
         capture_output=True,
-        text=True
+        text=True,
+        env=env
     )
 
-    # Assert successful exit
     assert result.returncode == 0, f"Benchmark failed with error:\n{result.stderr}"