Plugin dropping stderr output silently

[cowwoc]

The plugin is dropping stderr output. This is 100% reproducible.

Repro steps:

1. Create gulpfile.js containing:

var gulp = require("gulp");
gulp.task("default", ["non-existent"]);

2.. Configure Maven as follows:

<plugin>
    <groupId>com.github.eirslett</groupId>
    <artifactId>frontend-maven-plugin</artifactId>
    <version>0.0.20</version>
    <executions>
        <execution>
            <id>install-node-and-npm</id>
            <goals>
                <goal>install-node-and-npm</goal>
            </goals>
            <phase>generate-resources</phase>
            <configuration>
                <nodeVersion>v0.10.28</nodeVersion>
                <npmVersion>1.4.9</npmVersion>
            </configuration>
        </execution>
        <execution>
            <id>install-npm-dependencies</id>
            <goals>
                <goal>npm</goal>
            </goals>
            <phase>generate-resources</phase>
            <configuration>
                <arguments>install</arguments>
            </configuration>
        </execution>
        <execution>
            <id>gulp</id>
            <goals>
                <goal>gulp</goal>
            </goals>
            <phase>process-resources</phase>
            <configuration>
                <arguments>build</arguments>
            </configuration>
        </execution>
    </executions>
    <configuration>
        <workingDirectory>src/test/resources</workingDirectory>
    </configuration>
</plugin>

3.. Build the project.
4.. Maven fails with:

--- frontend-maven-plugin:0.0.20:gulp (gulp) @ frontend ---
Running 'gulp build --no-color' in ~/foo/frontend/src/test/resources
[14:46:56] Using gulpfile ~/foo/frontend/src/test/resources/gulpfile.js
------------------------------------------------------------------------
BUILD FAILURE
------------------------------------------------------------------------
Total time: 10.623s
Finished at: Wed Jan 21 14:46:56 EST 2015
Final Memory: 11M/277M
------------------------------------------------------------------------
Failed to execute goal com.github.eirslett:frontend-maven-plugin:0.0.20:gulp (gulp) on project frontend: Failed to run task: 'gulp build --no-color' failed. (error code 1) -> [Help 1]
org.apache.maven.lifecycle.LifecycleExecutionException: Failed to execute goal com.github.eirslett:frontend-maven-plugin:0.0.20:gulp (gulp) on project frontend: Failed to run task
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:213)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:153)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:145)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:84)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:59)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.singleThreadedBuild(LifecycleStarter.java:183)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:161)
    at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:320)
    at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:156)
    at org.apache.maven.cli.MavenCli.execute(MavenCli.java:537)
    at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:196)
    at org.apache.maven.cli.MavenCli.main(MavenCli.java:141)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:497)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:290)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:230)
    at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:409)
    at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:352)
Caused by: org.apache.maven.plugin.MojoFailureException: Failed to run task
    at com.github.eirslett.maven.plugins.frontend.mojo.GulpMojo.execute(GulpMojo.java:66)
    at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:101)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:209)
    ... 19 more
Caused by: com.github.eirslett.maven.plugins.frontend.lib.TaskRunnerException: 'gulp build --no-color' failed. (error code 1)
    at com.github.eirslett.maven.plugins.frontend.lib.NodeTaskExecutor.execute(NodeTaskExecutor.java:38)
    at com.github.eirslett.maven.plugins.frontend.mojo.GulpMojo.execute(GulpMojo.java:64)
    ... 21 more

5.. Run gulp manually from command-line:

# gulp
[14:49:57] Using gulpfile ~/foo/frontend/src/test/resources/gupfile.js
[14:49:57] Task 'non-existent' is not in your gulpfile
[14:49:57] Please check the documentation for proper gulpfile formatting

Expected behavior: Maven should output the 3 lines shown above.

[cowwoc]

It looks like there is some sort of race condition that causes the last line or two sent to stderr to never get printed.

[eirslett]

Hmm... It's s clumsy implementation of log forwarding, I'm not sure if there's a library that can do it better...

[cowwoc]

It turns out that we're actually losing lines sent to stdout, not stderr. I tracked the down problem to nodejs/node-v0.x-archive#8329; therefore, it is not fixable.

That said, I discovered a minor bug in your stderr-handling code. I will publish a PR soon.