Turn null parent class loader test into integration test

The test relies on the presence of the project JAR, so it needs to run
after the `package` phase.

Author: Nicolai Parlog

null-parent-classloader/src/test/java/NullParentClassLoaderIT.java

@@ -0,0 +1,63 @@
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.TestReporter;
+
+import java.net.MalformedURLException;
+import java.net.URL;
+import java.net.URLClassLoader;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+
+import static org.junit.jupiter.api.Assumptions.assumeTrue;
+
+public class NullParentClassLoaderIT {
+
+	/**
+	 * Attempt to load a class from the URLClassLoader that references a java.sql.* class. The
+	 * java.sql.* package is one of those not visible to the Java 9 bootstrap class loader that
+	 * was visible to the Java 8 bootstrap class loader.
+	 */
+	@Test
+	public void loadSqlDateUsingNullParent(TestReporter reporter) throws Exception {
+		URLClassLoader loader = buildLoader(reporter);
+
+		Class<?> jsqlUserClass = loader.loadClass("JavaSqlUser");
+		reporter.publishEntry("Loaded class", jsqlUserClass.toString());
+
+		Object jsqlUser = jsqlUserClass.getConstructor().newInstance();
+		reporter.publishEntry("Created instance", jsqlUser.toString());
+
+		loader.close();
+	}
+
+	/**
+	 * Build a URLClassLoader that only includes the null-parent-classloader artifact in its classpath,
+	 * along with the bootstrap class loader as its parent.
+	 *
+	 * @throws MalformedURLException
+	 * 		on failure to build the classpath URL
+	 */
+	private URLClassLoader buildLoader(TestReporter reporter) throws MalformedURLException {
+		String testRootFolder = NullParentClassLoaderIT.class.getResource("/").getPath();
+		reporter.publishEntry("Test classes folder", testRootFolder);
+		Path projectJar = Paths
+				.get(testRootFolder)
+				.getParent()
+				.resolve("null-parent-classloader-1.0-SNAPSHOT.jar");
+
+		assumeTrue(
+				projectJar.toFile().exists(),
+				"Project JAR must exist as " + projectJar.toString() + " for test to be executed.");
+		reporter.publishEntry("Project JAR", projectJar.toString());
+
+		URL path[] = { projectJar.toUri().toURL() };
+		// this is the parent that is required when running under Java 9:
+		// ClassLoader parent = ClassLoader.getPlatformClassLoader();
+		ClassLoader parent = null;
+		URLClassLoader loader = new URLClassLoader(path, parent);
+		reporter.publishEntry("Class loader", loader.toString());
+
+		return loader;
+	}
+
+}
+

null-parent-classloader/src/test/java/NullParentClassLoaderTest.java

@@ -76,6 +76,31 @@
 					</dependency>
 				</dependencies>
 			</plugin>
+			<plugin>
+				<artifactId>maven-failsafe-plugin</artifactId>
+				<version>2.19.1</version>
+				<dependencies>
+					<dependency>
+						<groupId>org.junit.platform</groupId>
+						<artifactId>junit-platform-surefire-provider</artifactId>
+						<version>1.0.2</version>
+					</dependency>
+					<dependency>
+						<!-- contains the engine that actually runs the Jupiter-tests -->
+						<groupId>org.junit.jupiter</groupId>
+						<artifactId>junit-jupiter-engine</artifactId>
+						<version>5.0.2</version>
+					</dependency>
+				</dependencies>
+				<executions>
+					<execution>
+						<goals>
+							<goal>integration-test</goal>
+							<goal>verify</goal>
+						</goals>
+					</execution>
+				</executions>
+			</plugin>
 		</plugins>
 	</build>