Empty argument tag should add empty string instead of null

[Anders-E]

Created new PR since I could not update the old one (#133, issue #132 ) due to the fork being deleted.

An empty argument tag such as:

<argument></argument>

Now adds an empty string instead of null to String[] args.

[ctubbsii]

I tested this and it works as expected. It preserves an empty argument.

My test case was (pom.xml):

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>

  <groupId>none</groupId>
  <artifactId>tester</artifactId>
  <version>1.0.0-SNAPSHOT</version>
  <packaging>pom</packaging>

  <build>
    <plugins>
      <plugin>
        <groupId>org.codehaus.mojo</groupId>
        <artifactId>exec-maven-plugin</artifactId>
        <version>3.0.0-SNAPSHOT</version>
        <executions>
          <execution>
            <id>testitnow</id>
            <phase>validate</phase>
            <goals>
              <goal>exec</goal>
            </goals>
            <configuration>
              <executable>./exec-test-script.sh</executable>
              <arguments>
                <argument>a</argument>
                <argument>b</argument>
                <argument />
                <argument>d</argument>
              </arguments>
            </configuration>
          </execution>
        </executions>
      </plugin>
    </plugins>
  </build>
</project>

The script, exec-test-script.sh contained:

#! /usr/bin/bash
echo Number of args is "${#@}"
for x in "$@"; do
  echo " ->$x<-"
done

I verified that the third argument was omitted before the PR, and that it was included as an empty argument after the PR.

---

However, there still doesn't appear to be any way to preserve whitespace, if you want an argument consisting of a space, as in:

  <configuration>
    <executable>tr</executable>
    <arguments>
      <argument> </argument>
      <argument>_</argument>
      <argument>&lt;filename</argument>
    </arguments>
  </configuration>

This might be an limit of Maven itself. It seems there may have been a regression of: https://issues.apache.org/jira/browse/MNG-5380

[Anders-E]

Noticed this was still open while checking my PRs. Should this be merged? @ctubbsii

[ctubbsii]

Noticed this was still open while checking my PRs. Should this be merged? @ctubbsii

I think it should, but I don't have commit access to this project.

[Anders-E]

@ctubbsii oh sorry, I just figured you did for some reason.

@olamy would this PR be of interest or should I close it?

[ctubbsii]

@ctubbsii oh sorry, I just figured you did for some reason.

No big deal. It's probably because GitHub says I "approved" it by giving a code review.

Pro tip: the gray checkmark next to an approval indicates the person submitted an approval as a non-committer performing a code review. A green checkmark would be displayed (like those at the bottom, by the status checks), if the reviewer had write access. It's a very subtle difference. Also the green checkmarks at the bottom can often be misinterpreted as a code review checkmark... I wish they used a different color for those.

[Anders-E]

Pro tip: the gray checkmark next to an approval indicates the person submitted an approval as a non-committer performing a code review. A green checkmark would be displayed (like those at the bottom, by the status checks), if the reviewer had write access. It's a very subtle difference. Also the green checkmarks at the bottom can often be misinterpreted as a code review checkmark... I wish they used a different color for those.

Ah I've never noticed that before, thank you for the tip!

[tisonkun]

I wonder if Windows performs differently in this case. See apache/opendal#6059 (comment)

We have:

<properties>
  <cargo-build.target/>
</properties>
<plugin>
    <artifactId>exec-maven-plugin</artifactId>
    <groupId>org.codehaus.mojo</groupId>
    <version>${exec-maven-plugin.version}</version>
    <executions>
        <execution>
            <id>compile-native-code</id>
            <phase>compile</phase>
            <goals>
                <goal>exec</goal>
            </goals>
            <configuration>
                <executable>python3</executable>
                <arguments>
                    <argument>${project.basedir}/tools/build.py</argument>
                    <argument>--target</argument>
                    <argument>${cargo-build.target}</argument>
                </arguments>
            </configuration>
        </execution>
    </executions>
</plugin>

This works on my Linux and macOS platform, but seems when running with mvnw.cmd on Windows, it doesn't work:

[INFO] --- exec:3.1.0:exec (compile-native-code) @ opendal ---
usage: build.py [-h] --classifier CLASSIFIER [--target TARGET]
                [--profile PROFILE] [--features FEATURES]
                [--enable-zigbuild ENABLE_ZIGBUILD]
build.py: error: argument --target: expected one argument
[ERROR] Command execution failed.
org.apache.commons.exec.ExecuteException: Process exited with an error: 2 (Exit value: 2)

[slawekjaranowski]

@tisonkun please create new issue, this one is closed 😄

[tisonkun]

@slawekjaranowski Yes and sorry I'm a bit lazy just now - here it is: #471