reference > Flags

--matching-diagnosis

Accepted by

opengrep test

See also

opengrep test, --matching-explanations

A failing test of opengrep test lists the lines that were missed or reported incorrectly. With --matching-diagnosis, the output also has a section that explains each of these lines: which part of the pattern did not match, or which condition removed the match.

--matching-explanations provides similar information in the JSON output of a scan.

## Examples

### Why a line was not matched

rules:  - id: find-eval    pattern: eval(...)    message: found eval    languages: [python]    severity: WARNING

# ruleid: find-evalevaluate(1)

$ opengrep test --matching-diagnosis . 2>&1 | grep -A2 'Matching diagnosis:'
Matching diagnosis:
find-eval.py: Unexpected lack of match at line 2
This line was never matched by any base pattern, nor introduced by any `focus-metavariable`.

The annotation asks for a match on line 2, which evaluate(1) does not produce, so the test fails and the diagnosis says the line matched no pattern at all.