Attempt to fix tests from any directory

Author: jhale

test/conftest.py

@@ -5,11 +5,26 @@
 # SPDX-License-Identifier:    LGPL-3.0-or-later
 """Test configuration."""
 
+import os
 import sys
 
 import pytest
 
 
+@pytest.fixture(autouse=True, scope="session")
+def add_cwd_to_syspath():
+    """Ensure the current working directory is in sys.path.
+
+    CFFI and ffcx.main compile/generate files into CWD by default. Without
+    this, importlib.import_module cannot find those files when pytest is invoked
+    from a directory that is not already on sys.path (e.g. the project root
+    rather than the test/ subdirectory).
+    """
+    cwd = os.getcwd()
+    if cwd not in sys.path:
+        sys.path.insert(0, cwd)
+
+
 @pytest.fixture(scope="module")
 def compile_args():
     """Compiler arguments."""