Test for textX dependency in self-check

Author: sebix

CHANGELOG.md

@@ -28,6 +28,7 @@ Please refer to the [NEWS](NEWS.md) for a list of changes which have an affect o
 
 #### Experts
 - `intelmq.bots.experts.asn_lookup.expert`: Print URLs to stdout only in verbose mode (PR#2591 by Sebastian Wagner).
+- `intelmq.bots.experts.sieve.expert`: Test for textX dependency in self-check (PR#2605 by Sebastian Wagner).
 
 #### Outputs
 

intelmq/bots/experts/sieve/expert.py

@@ -83,6 +83,9 @@ def check(parameters):
 
             metamodel = None
 
+            if metamodel_from_file is None:
+                raise MissingDependencyError("textx")
+
             try:
                 metamodel = metamodel_from_file(grammarfile)
             except TextXError as e: