How can I provide a conditional jvmarg for the ant junit command?

问题

Our shop has multiple build and test environments (Jenkins, Ant 1.9.6) set up on Java 6, 7 and 8. On Java 7 only, in order for our tests to run successfully, we need to add the JVM argument -XX:-UseSplitVerifier.

I can't use a condition inside junit, so I set a boolean property in the init task:

<condition property="usesplitverifier">
    <equals arg1="${ant.java.version}" arg2="1.7" />
</condition>

In my test task, I need to add jvmarg to junit only if that property is true:

<echo message="usesplitverifier: ${usesplitverifier}" />

<junit printsummary="yes" haltonfailure="no" fork="yes" forkmode="once" tempdir="${build.dir}">
    <jvmarg if="usesplitverifier" value="-XX:-UseSplitVerifier" />
    ...
</junit>

The output is:

        [echo] usesplitverifier: true

BUILD FAILED
C:\workspace\util\build.xml:141: jvmarg doesn't support the "if" attribute

I'm trying to avoid adding ant-contrib to our build/test environment. Also, I'd like to avoid adding more targets to the build script (I'm trying to simplify the build process). Is there another approach that might work here?

回答1:

While I was writing this question, I found the solution in another question that was closed as being too vague. I decided to post this question in order to provide a specific use case.

The if/unless namespaces may be used in any Ant command. In my case, I needed to add the if namespace to the project:

<project name="my-project" xmlns:if="ant:if" ...>

And then put the conditional on jvmarg as follows:

<junit printsummary="yes" haltonfailure="no" fork="yes" forkmode="once" tempdir="${build.dir}">
    <jvmarg if:set="usesplitverifier" value="-XX:-UseSplitVerifier" />
    ...
</junit>

The reason if:set works in this case is that if ${ant.java.version} is not 1.7, the property remains unset.

Caveats (acceptable in my case):

• The if/unless namespaces are only available since Ant 1.9.1.
• Prior to Ant 1.6, ${ant.java.version} returns the version of the JVM that Ant was compiled with.

来源：https://stackoverflow.com/questions/35393545/how-can-i-provide-a-conditional-jvmarg-for-the-ant-junit-command