ArgumentListTooLong error running junit tests

[wfscheper]

Describe the bug
I have a junit test that transitively depends on ~90 java files. This causes pants to generate a java command to run that test file which is too long, since each compiled jar is listed 3 times.

I was able to modify the __run.sh script to use directory globs instead, but I'm not sure if that's a reasonable solution for pants (line wrapping added for readability):

#!/usr/bin/env bash
# This command line should execute the same process as pants did internally.
cd /tmp/pants-sandbox-acB2Fk
env -i \
COURSIER_ARCHIVE_CACHE=.cache/arc \
COURSIER_CACHE=.cache/5ca0e91bb431137f03c7a4f22d8308c85710964f80926a14e1c040e696573039/jdk \
COURSIER_JVM_CACHE=.cache/v1 \
PANTS_INTERNAL_ABSOLUTE_PREFIX= \
/usr/bin/bash __jdk/jdk.sh __java_home/bin/java \
  -cp $'__jdk/*:*:__toolcp/*' \
  -Xmx512m \
  org.junit.platform.console.ConsoleLauncher \
  --classpath $'*' \
  --scan-class-path $'*' \
  --reports-dir \
  __reports_dir/src.testFixtures.java.com.my.test.TestFile.java.tests

Pants version
2.17.0

OS
Linux

[benjyw]

Java supports @/path/to/file where the file contains command line args. So that's probably the most robust solution. Shouldn't be too hard to do, if you want to take a crack at it?

[wfscheper]

Sure! I'll see what I can figure out.

[wfscheper]

Started investigating what using @-files would entail, and there's a couple complications related to ParsedJVMCommandLines in the rust engine.

ParsedJVMCommandLines requires that the command contain a -cp or -classpath flag before the main class, and it requires that the main class be on the command line as well. Without touching the rust code, I can change setup_junit_for_target to use an @-file for the ConsoleLauncher args, which should solve most cases. However, a sufficiently large dependency tree could trip the ArgumentListTooLong error just on the JVM classpath. Fixing that edge case will require updating ParsedJVMCommandLines to also parse @-file(s).

Will try and get something written for the ConsoleLauncher args for now.

[benjyw]

Sounds good. Fixing in rust wouldn't be too hard either, I suspect. For example, we can have a dedicated @-file just for the classpath and a separate one for the consolelauncher args.