Add a test case

Author: brian-mcnamara

java/test/com/github/bazel_contrib/contrib_rules_jvm/junit5/BUILD.bazel

@@ -43,6 +43,7 @@ java_test_suite(
         artifact("org.mockito:mockito-core", "contrib_rules_jvm_tests"),
         artifact("org.opentest4j:opentest4j", "contrib_rules_jvm_tests"),
     ] + junit5_vintage_deps("contrib_rules_jvm_tests"),
+    resources = glob(["resources/*"])
 )
 
 java_test_suite(

java/test/com/github/bazel_contrib/contrib_rules_jvm/junit5/JavaTestSuiteTest.java

@@ -0,0 +1,38 @@
+package com.github.bazel_contrib.contrib_rules_jvm.junit5;
+
+import org.junit.jupiter.api.Test;
+
+import java.io.File;
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.zip.ZipFile;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.fail;
+
+public class JavaTestSuiteTest {
+
+    @Test
+    public void testClasspathDoesNotContainDuplicateResources() throws IOException {
+        final String resourceName = "duplicate_resource_test.txt";
+        String[] classpath = System.getProperty("java.class.path").split(":");
+        List<String> resourcesFound = new ArrayList<>();
+        for (String entry : classpath) {
+            if (entry.endsWith(".jar")) {
+                try (ZipFile zipfile = new ZipFile(new File(entry))) {
+                    zipfile.entries().asIterator().forEachRemaining(zipEntry -> {
+                        if (zipEntry.getName().endsWith(resourceName)) {
+                            resourcesFound.add(entry);
+                        }
+                    });
+                }
+            } else {
+                fail("Classpath contains non-jar files");
+            }
+        }
+        assertEquals(1, resourcesFound.size(),
+                "Expected a single instance of a resource to be on the classpath, instead found entries in: " + resourcesFound);
+    }
+}

java/test/com/github/bazel_contrib/contrib_rules_jvm/junit5/resources/duplicate_resource_test.txt

@@ -0,0 +1 @@
+Simple resource to validate suites only pick up a single resource