Add Java Plugin to the Gradle build

[jeandersonbc]

The Gradle Java plugin already has common build tasks for Java/JVM project such as generating jars, compiling classes, and so on. Also, it is configurable to support jpf project layout.

More info: https://docs.gradle.org/current/userguide/tutorial_java_projects.html

[jeandersonbc]

I added a Gradle script for compilation and test execution. I compared the number of tests executed and both (Gradle and Ant) are consistent.

However, only 75% of tests are passing on the Gradle build.
I sampled some errors to investigate, and I noticed that some of them are due to hardcoded paths on tests, like here in the MethodInfoTest class:

  @Test
  public void testMethodArgs() {
    File file = new File("build/tests/gov/nasa/jpf/jvm/MethodInfoTest$MyClass.class");

The build directory generated by Gradle has a different layout.
I need to confirm all cases first to be 100% sure but I believe that all errors are similar to this.
Changing those hardcoded paths doesn't seem to help the problem at all.
I need to figure a way to preserve the generated directories.

[jeandersonbc]

I found similar entry lines in the standard output of other tests:

running jpf with args: +listener=.test.mc.basic.BreakTest$FieldBreaker +vm.max_transition_length=1000000
[WARNING] unknown classpath element: /Users/jeandersonbc/projects/jpf/jpf-core/build/tests
[WARNING] unknown classpath element: /Users/jeandersonbc/projects/jpf/jpf-core/build/jpf-classes.jar
[WARNING] unknown classpath element: /Users/jeandersonbc/projects/jpf/jpf-core/build/examples
[WARNING] unknown classpath element: /Users/jeandersonbc/projects/jpf/jpf-symbc/build/jpf-symbc-classes.jar
...

[jeandersonbc]

I made some marginal improvement by making the generated directory three similar to the ant-generated build directories. Now, 78% of tests pass.

This means that only 3% depends on a compiled class file as a test resource (passing now, since the .class files exist on the expected place)
All the remaining 22% failed tests depend on a jar file as a test resource.

I must work on this to have 100% of tests passing.

I wonder if jar dependent tests shouldn't be considered integration tests and be executed only in a later stage of the build cycle.

[cyrille-artho]

Let's try to get the paths fixed by eliminating hard-coded paths wherever possible.
Perhaps we can define some compile-time settings for this.
The paths will change again with JDK 9/10, so having a single configuration entry for them would be good.

[jeandersonbc]

Alright, I'm closing this issue for now, since changes were merged.