[GitHub] [kafka] vvcephei commented on a change in pull request #8546: MINOR: document how to escape json parameters to ducktape tests

[GitBox <gi...@apache.org>]

vvcephei commented on a change in pull request #8546:
URL: https://github.com/apache/kafka/pull/8546#discussion_r414897161



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File path: tests/README.md
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@@ -36,6 +36,10 @@ TC_PATHS="tests/kafkatest/tests/client/pluggable_test.py::PluggableConsumerTest"
 ```
 TC_PATHS="tests/kafkatest/tests/client/pluggable_test.py::PluggableConsumerTest.test_start_stop" bash tests/docker/run_tests.sh
 ```
+* Run a specific test method with specific parameters
+```
+TC_PATHS="tests/kafkatest/tests/streams/streams_upgrade_test.py::StreamsUpgradeTest.test_metadata_upgrade" _DUCKTAPE_OPTIONS='--parameters '\''{"from_version":"0.10.1.1","to_version":"2.6.0-SNAPSHOT"}'\' bash tests/docker/run_tests.sh

Review comment:
       Haha, having just spent several hours settling on this exact sequence of characters, I can certify that it's correct ;) 
   
   Actually, I would like to get at least one other person to try it out. Do you mind?
   
   To answer your question, here's how it works:
   first string (wrapped in single quotes for consistency with the second string): `--parameters `
   first escaped single quote: `\'`
   second string (wrapped in single quotes to avoid evaluating the special characters): `{"from_version":"0.10.1.1","to_version":"2.6.0-SNAPSHOT"}`
   second escaped single quote: `\'`
   
   Following Bash rules, a sequence of strings and characters just get concatenated, so all of the above gets smashed together to form the desired final string:
   `--parameters '{"from_version":"0.10.1.1","to_version":"2.6.0-SNAPSHOT"}'`
   
   which will then be evaluated _again_ by Bash inside the docker container, so that the final argument to ducktape is the desired argument list: `--parameters`, followed by `{"from_version":"0.10.1.1","to_version":"2.6.0-SNAPSHOT"}`.




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