[jira] [Created] (NIFI-6058) MockPropertyValue is overzealous about checking for expression evaluation

["Sergei Zhirikov (JIRA)" <ji...@apache.org>]

Sergei Zhirikov created NIFI-6058:
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             Summary: MockPropertyValue is overzealous about checking for expression evaluation
                 Key: NIFI-6058
                 URL: https://issues.apache.org/jira/browse/NIFI-6058
             Project: Apache NiFi
          Issue Type: Bug
    Affects Versions: 1.9.0, 1.8.0
            Reporter: Sergei Zhirikov


MockPropertyValue.getValue() (and other methods of the same family) will throw an IllegalStateException when called on an object that wasn't returned from evaluateAttributeExpressions(). It does that whenever the property in question supports expression language (that is when expectExpressions is true). That kind of logic is too strict. It makes sense to throw an exception only when the value of the property actually contains something to be evaluated, in other words, when isExpressionLanguagePresent() would return true.
 Rationale: a processor could contain the following code, or something similar:

PropertyValue pv = processContext.getProperty(propertyDescriptor);
 if (pv.isSet() && pv.isExpressionLanguagePresent())
     pv = pv.evaluateAttributeExpressions(flowFile);
 String value = pv.getValue();

This is a valid thing to do, and it works fine in real NiFi, but fails in tests with nifi-mock. Unfortunately, calling testRunner.setValidateExpressionUsage(false) does not help, because then isExpressionLanguagePresent() will always return false.

Note: I have only tested this with 1.8.0, but the relevant code in the master branch is the same, so I assume the issue applies to the latest version as well.



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