[MCHECKSTYLE-431] Avoid creating unnecessary target files for pom projects

[jira-importer]

Alexis Jehan opened MCHECKSTYLE-431 and commented

Because pom projects do not have Java code, It is not necessary to create "target/checkstyle-cachefile", "target/checkstyle-checker.xml", "target/checkstyle-result.xml" and "target/checkstyle-suppressions.xml" files for these projects.

Maven configuration:

<plugin>
	<groupId>org.apache.maven.plugins</groupId>
	<artifactId>maven-checkstyle-plugin</artifactId>
	<version>3.2.1</version>
	<dependencies>
		<dependency>
			<groupId>com.puppycrawl.tools</groupId>
			<artifactId>checkstyle</artifactId>
			<version>10.9.3</version>
		</dependency>
	</dependencies>
	<configuration>
		<configLocation>checkstyle.xml</configLocation>
		<suppressionsLocation>checkstyle-suppressions.xml</suppressionsLocation>
		<includeTestSourceDirectory>true</includeTestSourceDirectory>
		<violationSeverity>info</violationSeverity>
	</configuration>
	<executions>
		<execution>
			<id>checkstyle-check</id>
			<phase>validate</phase>
			<goals>
				<goal>check</goal>
			</goals>
		</execution>
	</executions>
</plugin>

Maven output:

[INFO] --- checkstyle:3.2.1:check (checkstyle-check) @ parent-project ---
[INFO] You have 0 Checkstyle violations.

Content of the generated "target/checkstyle-result.xml":

<?xml version="1.0" encoding="UTF-8"?>
<checkstyle version="10.9.3">
</checkstyle>

---

Affects: 3.2.1

[jira-importer]

Michael Osipov commented

You declared the plugin in the parent and to it to propagate?

[jira-importer]

Alexis Jehan commented

Yes exactly

[jira-importer]

Michael Osipov commented

What about aggregator runs?

[jira-importer]

Alexis Jehan commented

I have just tested it, the behavior is the same except that the checkstyle plugin (defined only in the agregator "pom.xml") is not inherited by modules. But unnecessary target files are still generated for the agregator.

I think every "pom.xml" defined with <packaging>pom</packaging> should be excluded from the "check" goal.

[jira-importer]

Michael Osipov commented

I will check this again, but I am afraid that those files are created by checkstyle directly. This means they would be logically opaque...

[jira-importer]

Michael Osipov commented

Yes, not easily possible: Look here:

maven-checkstyle-plugin/src/main/java/org/apache/maven/plugins/checkstyle/AbstractCheckstyleReport.java

Lines 611 to 637 in c6dbdfe

	protected AuditListener getListener() throws MavenReportException {
	AuditListener listener = null;
	if (outputFileFormat != null && !outputFileFormat.isEmpty()) {
	File resultFile = outputFile;
	OutputStream out = getOutputStream(resultFile);
	if ("xml".equals(outputFileFormat)) {
	listener = new XMLLogger(out, OutputStreamOptions.CLOSE);
	} else if ("plain".equals(outputFileFormat)) {
	listener = new DefaultLogger(out, OutputStreamOptions.CLOSE);
	} else if ("sarif".equals(outputFileFormat)) {
	try {
	listener = new SarifLogger(out, OutputStreamOptions.CLOSE);
	} catch (IOException e) {
	throw new MavenReportException("Failed to create SarifLogger", e);
	}
	} else {
	// TODO: failure if not a report
	throw new MavenReportException(
	"Invalid output file format: (" + outputFileFormat + "). Must be 'plain', 'sarif' or 'xml'.");
	}
	}
	return listener;
	}

Checkstyle requires us to pass an output stream which means the file needs to creates in anycase. Maybe roman.ivanov could give us an advice here...

[jira-importer]

Alexis Jehan commented

That would be possible with such a "NullOutputStream", but yeah this is not a clean solution. Better one would be not to run checkstyle if we detect that this is useless (Like respectively the javadoc plugin with "Not executing Javadoc as the project is not a Java classpath-capable package" or the surefire plugin with "No tests to run.").

[jira-importer]

Michael Osipov commented

How can we know for sure that we can skip the project?

Here is the code:

if (!isAggregator() || !"pom".equalsIgnoreCase(project.getPackaging())) {
    ArtifactHandler artifactHandler = project.getArtifact().getArtifactHandler();
    if (!"java".equals(artifactHandler.getLanguage())) {
        getLog().info("Not executing Javadoc as the project is not a Java classpath-capable package");
        return;
    }
}

Does this apply to other JVM languages? I mean I could likely test Groovy code with Surefire, no?

The NullOutputStream is pointless because you cannot know whether there will be something and if you know you can skip execution altogether.

[jira-importer]

Alexis Jehan commented

Checkstyle only applies to Java, and a Maven module with a pom packaging value does not have any Java code. So we could exclude those projects the same way the Javadoc plugin is doing.

[jira-importer]

Michael Osipov commented

If roman.ivanov approves that I am willing to change the code.

[jira-importer]

Alexis Jehan commented

That has been months, still no reply, how could we contact him?