Default scenario logging does not show up in step notifications

[IgnasCi]

👓 What did you see?

Scenario logs (scenario.log()) does not show up in step notifications. This started happening since 7.3.3 version.

✅ What did you expect to see?

Logs should be shown in step notifications.

📦 Which tool/library version are you using?

Maven project
Intellij 2022.1

🔬 How could we reproduce it?

Steps to reproduce the behavior:

1. Clone project from https://github.com/IgnasCi/cucumberIssue.
2. Try to run test runner (TestRunner.class)
3. Check step notification (lest logging *), logs are not shown.
4. Replace cucumber-java version to 7.3.2 in pom.xml, refresh maven project.
5. Rerun project
6. Select any step notification (test logging *) in console to check if logs are shown.

📚 Any additional context?

7.3.2	7.3.4

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[aslakhellesoy]

Logs should be shown in step definitions.

I'm not sure I understand what you mean. A step definition is a Java method. What do you mean when you say logs should be shown in step definitions?

Do you mean they should be printed to STDOUT?

[aslakhellesoy]

If it's about logs not being printed to STDOUT, it could be a regression introduced in #2541 where there were some changes about how output is flushed.

[IgnasCi]

Ah, sorry, I meant step notifications.... (check screenshots).

Do you mean they should be printed to STDOUT?

Partly yes - If i click on step notification (7.3.4), there are no logs flushed to STDOUT. However, at the same time if i click on scenario notification level, all logs in STDOUT are visible. 7.3.2 / or below - all good for both cases. So the problem is related only with step notifications feature, which is enabled via:

CucumberOptions -> stepNotifications = true.

[mpkorstanje]

The problem isn't a lack of flushing, the problem is too much buffering.

cucumber-jvm/core/src/main/java/io/cucumber/core/plugin/PrettyFormatter.java

Lines 51 to 53 in 44e0bfd

	public PrettyFormatter(OutputStream out) {
	this.out = new NiceAppendable(new UTF8OutputStreamWriter(out));
	}

The UTF8OutputStreamWriter is a Writer which has a default buffer of 1KiB. If less then 1KiB is written, nothing is flushed until the end of the test execution when the stream is closed. When writing to System.out this buffer isn't necessary.

This buffer could be eliminated by adding support for a PrintStream argument in the PluginFactory. Plugins that were specified without an argument would receive System.out directly. For plugins that did specify an argument a PrintWriter with UTF-8 encoding would have to be created.

Once supported the PrettyFormatter could be declared as:

    public PrettyFormatter(PrintStream out) {
        this.out = new NiceAppendable(out);
    }

However note:

cucumber-jvm/core/src/main/java/io/cucumber/core/plugin/PluginFactory.java

Lines 54 to 59 in 44e0bfd

	private PrintStream defaultOut = new PrintStream(System.out) {
	@Override
	public void close() {
	// We have no intention to close System.out
	}
	};

To prevent closing System.out it is wrapped with a decorator. This adds another buffer to the chain. This would also have to be eliminated as well. Presumably by properly delegating all methods except .close() to System.out.