[Gradle] ServiceLoader issues in test cases

[roguexz]

Describe the bug
If a test case pulls in a library that provides a SPI for a service used by Quarkus test configuration (e.g., FileSystemProvider), then the test cases fail during boot time with a ClassCastException due to the classloader separation introduced in 1.3

Consider the following scenario,

• In order to setup a mock SSH server, the project declares a test dependency on org.apache.sshd:sshd-sftp
• This library provides an implementation for a virtual file system, SftpFileSystemProvider
• In the project you define a QuarkusTestResource for configuring the mock SSH server
• When you run the test case, it fails with a ClassCastException during boot time.

Expected behavior
The mock SSH server should have started up properly.

Actual behavior
We observe a ClassCastException instead.

To Reproduce
Steps to reproduce the behavior:

1. Clone the quarkus-sample repository
2. Run ./gradlew clean build

Configuration

N/A

Screenshots
N/A

Environment (please complete the following information):

• Output of uname -a or ver: Darwin LM-SJN-40002334 18.7.0 Darwin Kernel Version 18.7.0: Mon Feb 10 21:08:45 PST 2020; root:xnu-4903.278.28~1/RELEASE_X86_64 x86_64
• Output of java -version: openjdk version "1.8.0_232"
• GraalVM version (if different from Java): N/A
• Quarkus version or git rev: 1.4.1.Final
• Build tool (ie. output of mvnw --version or gradlew --version): Gradle 6.3

Additional context
N/A

[quarkusbot]

/cc @quarkusio/devtools

[aloubyansky]

Haven't yet looked deeper but with master I get a different error

> Task :compileTestJava FAILED

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':compileTestJava'.
> Could not resolve all files for configuration ':testCompileClasspath'.
   > Could not find com.google.inject:guice:4.2.1.
     Required by:
         project : > io.quarkus:quarkus-junit5:999-SNAPSHOT > io.quarkus:quarkus-bootstrap-core:999-SNAPSHOT > org.apache.maven:maven-embedder:3.6.3
         project : > io.quarkus:quarkus-bom:999-SNAPSHOT > org.apache.maven:maven-core:3.6.3

[roguexz]

I have configured the build script to use only mavenLocal when working with the SNAPSHOT. That was because I had a different setup locally (with the VPN and internal repositories, etc.).

You will want to edit those inclusions in the build.gradle. Sorry about it.

[aloubyansky]

Sorry, haven't even looked into it as I had another issue on the list. Now that I tried it again I see the CCE in master as well.

[aloubyansky]

@stuartwdouglas what do you think about this change aloubyansky@d64b6ae
BTW, I've copied the original reproducer adapted to use Quarkus 999-SNAPSHOT here https://github.com/aloubyansky/playground/tree/quarkus-issue-9017