Add Real Jenkins rule test to identify classpath issue

src/test/java/io/jenkins/plugins/oras/java/api/RealJenkinsTest.java

@@ -0,0 +1,40 @@
+package io.jenkins.plugins.oras.java.api;
+
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+
+import java.util.logging.Level;
+import land.oras.ContainerRef;
+import land.oras.Index;
+import land.oras.Registry;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.RegisterExtension;
+import org.junit.jupiter.api.parallel.Execution;
+import org.junit.jupiter.api.parallel.ExecutionMode;
+import org.jvnet.hudson.test.junit.jupiter.RealJenkinsExtension;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+@Execution(ExecutionMode.SAME_THREAD)
+class RealJenkinsTest {
+
+    /**
+     * Logger for this class
+     */
+    private static final Logger LOG = LoggerFactory.getLogger(RealJenkinsTest.class);
+
+    @RegisterExtension
+    private final RealJenkinsExtension extension = new RealJenkinsExtension()
+            .withLogger("land.oras", Level.FINEST)
+            .withLogger(RealJenkinsTest.class, Level.FINEST);
+
+    @Test
+    void pullIndexTest() throws Throwable {
+        extension.then(r -> {
+            Registry registry = Registry.builder().build();
+            ContainerRef containerRef1 = ContainerRef.parse("ghcr.io/oras-project/oras:main");
+            Index index = registry.getIndex(containerRef1);
+            assertNotNull(index);
+            LOG.info("Index found: {}", index);
+        });
+    }
+}

src/test/java/io/jenkins/plugins/oras/java/api/SmokeTest.java

@@ -42,7 +42,7 @@
 
 @WireMockTest
 @Execution(ExecutionMode.CONCURRENT)
-public class SmokeTest {
+class SmokeTest {
     @Test
     void shouldListTags(WireMockRuntimeInfo wmRuntimeInfo) {