How to get the exception that was thrown when a Cucumber test failed in Java?

Question

I can perform actions on test failure by using:

@After
public void afterTest(Scenario scenario) {
    if (scenario.isFailed()) {
        /*Do stuff*/
    }
}

However some of the actions I need to perform depend on the Exception that was thrown and in what context it was thrown. Is there a way to get the Throwable that caused the test to fail? For example in JUnit I would do this by extending TestWatcher and add a rule to my tests:

@Override
protected void failed(Throwable e, Description description) {
    /*Do stuff with e*/
}

However the cucumber-junit iplementation does not allow the use of rules, so this solution would not work with Cucumber.

I don't think I need to explain why accessing a thrown exception on test failure would be useful, however I will still provide an Example:

My test environment is not always stable, so my tests might fail unexpectedly at any moment (there's no specific place I can try to catch the exception since it could occur at any time). When this happens I need the test to reschedule for another attempt, and log the incident so that we can get some good statistical data on the environment instability (when, how frequent, how long etc.)

Answer 1

The problem with the work around suggested by Frank Escobar:

By using reflection to reach into a frameworks internals you're depending on implementation details. This is a bad practice, when ever the framework changes its implementation your code may break as you will observe in Cucumber v5.0.0.

Hooks in Cucumber are designed to manipulate the test execution context before and after a scenario. They're not made to report on the test execution itself. Reporting is cross cutting concern and best managed by using the plugin system.

For example:

package com.example;

import io.cucumber.plugin.ConcurrentEventListener;
import io.cucumber.plugin.event.EventPublisher;
import io.cucumber.plugin.event.Result;
import io.cucumber.plugin.event.Status;
import io.cucumber.plugin.event.TestCase;
import io.cucumber.plugin.event.TestCaseFinished;

public class MyTestListener implements ConcurrentEventListener {
    @Override
    public void setEventPublisher(EventPublisher publisher) {
        publisher.registerHandlerFor(TestCaseFinished.class, this::handleTestCaseFinished);
    }

    private void handleTestCaseFinished(TestCaseFinished event) {
        TestCase testCase = event.getTestCase();
        Result result = event.getResult();
        Status status = result.getStatus();
        Throwable error = result.getError();
        String scenarioName = testCase.getName();
        String id = "" + testCase.getUri() + testCase.getLine();
        System.out.println("Testcase " + id + " - " + status.name());
    }
}

When using JUnit 4 and TestNG you can activate this plugin using:

@CucumberOptions(plugin="com.example.MyTestListener")

With JUnit 5 you add it to junit-platform.properties:

cucumber.plugin=com.example.MyTestListener 

Or if you are using the CLI

--plugin com.example.MyTestListener