NIOInspector is a specialized Maven plugin designed to identify and fix non-idempotent-outcome (NIO) flaky tests within Java projects. An NIO flaky test, due to self-polluting shared state, consistently passes in the initial run and fails in subsequent executions within the same environment.

• Java 9 to 21 (for detection).
• Maven 3.5+ (for detection).
• Python 3.0+ (for test fixing).

To build the plugin, run:

mvn clean install

The plugin is released to Maven Central, so the commands below can be run without building locally.

To detect NIO flaky tests in your project, execute the following command in the root directory of the target project:

mvn edu.illinois:NIOInspector:rerun

Optional arguments:

• Use -Dtest=${path.to.testClass#testMethod} to filter individual test classes or methods.
• Use -DnumReruns to configure the number of reruns for each test.

This command generates a .NIOInspector folder in the current directory, containing a folder for each execution timestamp (e.g., 2024-01-01-00-00-01) with a rerun-results.log for debugging purposes.

Run the following command to download the Python script for fixing:

mvn edu.illinois:NIOInspector:downloadFixer

Run the following command to collect information on NIO tests:

mvn edu.illinois:NIOInspector:collectTestInfo

Optional arguments:

• Use -logFile=${path.to.most.recent.log} to specify a specific run for detection (default uses the most recent rerun).

This command collects a list of potential NIO tests along with their stack traces and relevant source code, stored in .NIOInspector/{timestamp}/{full_path_test_name}.

Use GPT-4 to determine relevant source code for fixing NIO tests. Run:

python3 GPT_NIO_fixer.py decide_relevant_source_code {your_api_key_for_GPT}

Optional arguments:

• Use -timestamp=${xxxx-xx-xx-xx-xx-xx} to specify a certain run for detection (default uses the most recent rerun).

Run the following command to gather relevant source code based on the advice from the agent in Step 3:

mvn edu.illinois:NIOInspector:collectRelevantSourceCode

Optional arguments:

• Use -logFile=${path.to.most.recent.log} to specify a certain run for detection (default uses the most recent rerun).

Finally, use LLM to fix NIO tests based on gathered information. Run:

python3 GPT_NIO_fixer.py fix {your_api_key_for_GPT}

Optional arguments:

• Use -timestamp=${xxxx-xx-xx-xx-xx-xx} to specify a certain run for detection (default uses the most recent rerun).
• Use -max_tokens={num_tokens} to configure the maximum number of tokens in the patch (default is 1000).
• Use -extra_prompt={your_prompt} for additional ad hoc requirements (e.g., "Do not add comments", default is empty string).

This command generates a patch for each of the possible NIO test, stored in .NIOInspector/{timestamp}/{full_path_test_name}/patch.txt.