[classifier] Catching KeyError when parsing a record

[chunyong-lin]

to: @airbnb/streamalert-maintainers
size: small
resolves N/A

Background

Catch KeyError during a record parsing in the classifier. It may result a KeyError exception when a record is mis-classified, although this situation is rare.

Changes

• Catch KeyError and return False. It will result Failed Parses in Rule Processor if a record is mis-classified.

Testing

• Rule testing

python manage.py lambda test --processor all
...
StreamAlertCLI [INFO]: (63/63) Successful Tests
StreamAlertCLI [INFO]: (34/34) Alert Tests Passed

• Unit testing

./tests/scripts/unit_tests.sh
...
Ran 736 tests in 10.559s

OK

[coveralls]

Coverage decreased (-0.07%) to 97.607% when pulling c7d8205 on catch_key_error_in_classifier into 8c3d246 on master.