test: use ModuleNotFoundError in interface_ipc.py
What the developer wrote
Authored by fanquake
test: use ModuleNotFoundError in interface_ipc.py
Change this so we catch the case where the capnp shared libs have been
updated, and can no-longer be loaded by the Python module, resulting in
a skipped test, even though pycapnp is installed. i.e:
```bash
stderr:
Traceback (most recent call last):
File "/root/ci_scratch/build/test/functional/interface_ipc.py", line 20, in <module>
import capnp # type: ignore[import] # noqa: F401
^^^^^^^^^^^^
File "/usr/local/lib64/python3.14/site-packages/capnp/__init__.py", line 36, in <module>
from .version import version as __version__
File "/usr/local/lib64/python3.14/site-packages/capnp/version.py", line 1, in <module>
from .lib.capnp import _CAPNP_VERSION_MAJOR as LIBCAPNP_VERSION_MAJOR # noqa: F401
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
ImportError: libcapnpc.so.1.0.1: cannot open shared object file: No such file or directory
```
Failing in this way should make it clear that `pycapnp` needs to be
reinstalled/rebuilt.
If `pycapnp` is not installed, the test still skips as expected:
```bash
Remaining jobs: [interface_ipc.py]
1/1 - interface_ipc.py skipped (capnp module not available.)
TEST | STATUS | DURATION
interface_ipc.py | ○ Skipped | 0 s
```
Fixes: #34016.
Co-authored-by: Ryan Ofsky <ryan@ofsky.org>
What changed, and why it matters
This is a tiny change to a single Bitcoin Core test file. It makes the test skip cleanly when the optional capnp Python library is broken or missing, instead of crashing with a confusing error. It does not affect normal Bitcoin node operation, wallets, consensus, networking, or any user-facing security behavior.
No security action needed. Treat as a normal test-quality improvement.
Security signals we found
No strong security signals were identified.
Evidence from the diff
The patch changes the exception handler in test/functional/interface_ipc.py from catching ImportError to catching ModuleNotFoundError. ModuleNotFoundError is a subclass of ImportError raised only when the module itself cannot be found, so a missing pycapnp still skips the test. Other ImportError subclasses—such as the one raised when pycapnp is installed but its native shared-library dependency (libcapnpc.so) is missing—will now propagate and show a clear traceback, helping developers diagnose environment issues. This is purely a test-framework robustness improvement.
Changed components
test/functional/interface_ipc.pyInspect captured patch +1 / −1
diff --git a/test/functional/interface_ipc.py b/test/functional/interface_ipc.py
index c7183c1b..6beba66a 100755
--- a/test/functional/interface_ipc.py
+++ b/test/functional/interface_ipc.py
@@ -42,7 +42,7 @@ class CoinbaseTxData:
# Test may be skipped and not have capnp installed
try:
import capnp # type: ignore[import] # noqa: F401
-except ImportError:
+except ModuleNotFoundError:
pass
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Why this scored 15/100
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