SOLR-8874: Make Solr tests work with Java 9 Jigsaw

lucene/test-framework/src/java/org/apache/lucene/util/LuceneTestCase.java

@@ -568,11 +568,14 @@ public abstract class LuceneTestCase extends Assert {
   private final static long STATIC_LEAK_THRESHOLD = 10 * 1024 * 1024;
 
   /** By-name list of ignored types like loggers etc. */
-  private final static Set<String> STATIC_LEAK_IGNORED_TYPES = 
+  private final static Set<String> STATIC_LEAK_IGNORED_TYPES = Collections.unmodifiableSet(new HashSet<>(Arrays.asList(
-      Collections.unmodifiableSet(new HashSet<>(Arrays.asList(
       "org.slf4j.Logger",
       "org.apache.solr.SolrLogFormatter",
-      EnumSet.class.getName())));
+      "java.io.File", // Solr sometimes refers to this in a static way, but it has a "java.nio.fs.Path" inside 
+      Path.class.getName(), // causes problems because interface is implemented by hidden classes
+      Class.class.getName(),
+      EnumSet.class.getName()
+  )));
 
   /**
    * This controls how suite-level rules are nested. It is important that _all_ rules declared

solr/common-build.xml

@@ -152,10 +152,13 @@
 
   <!-- 
     We don't want to run HDFS tests on Windows, because they require Cygwin.
-    If you have Cygwin or manually raised permgen, you can override this property on command line:
+    We don't want to run HDFS tests on Java 9 Jigsaw, because Hadoop/HDFS is completely broken with Java's module system.
   -->
   <condition property="tests.disableHdfs" value="true">
-    <os family="windows"/>
+    <or>
+      <os family="windows"/>
+      <available classname="java.lang.reflect.Module"/>
+    </or>
   </condition>
 
   <target name="validate" depends="compile-tools">

solr/contrib/morphlines-cell/src/test/org/apache/solr/morphlines/cell/SolrCellMorphlineTest.java

@@ -42,7 +42,8 @@ public class SolrCellMorphlineTest extends AbstractSolrMorphlineTestBase {
   @BeforeClass
   public static void beforeClass2() {
     assumeFalse("FIXME: Morphlines currently has issues with Windows paths", Constants.WINDOWS);
-    assumeFalse("This test fails with Java 9 (https://issues.apache.org/jira/browse/PDFBOX-3155)", Constants.JRE_IS_MINIMUM_JAVA9);
+    assumeFalse("This test fails with Java 9 (https://issues.apache.org/jira/browse/PDFBOX-3155, https://issues.apache.org/jira/browse/SOLR-8876)",
+        Constants.JRE_IS_MINIMUM_JAVA9);
   }
 
   @Before

solr/contrib/morphlines-core/src/test/org/apache/solr/morphlines/solr/AbstractSolrMorphlineTestBase.java

@@ -21,6 +21,7 @@ import com.google.common.base.Joiner;
 import com.google.common.io.Files;
 import com.typesafe.config.Config;
 import org.apache.commons.io.FileUtils;
+import org.apache.lucene.util.Constants;
 import org.apache.solr.SolrTestCaseJ4;
 import org.apache.solr.client.solrj.SolrClient;
 import org.apache.solr.client.solrj.SolrQuery;
@@ -85,6 +86,8 @@ public class AbstractSolrMorphlineTestBase extends SolrTestCaseJ4 {
 
   @BeforeClass
   public static void beforeClass() throws Exception {
+    assumeFalse("This test fails on Java 9 (https://issues.apache.org/jira/browse/SOLR-8876)", Constants.JRE_IS_MINIMUM_JAVA9);
+    
     // TODO: test doesn't work with some Locales, see SOLR-6458
     savedLocale = Locale.getDefault();
     Locale.setDefault(Locale.ENGLISH);

solr/contrib/morphlines-core/src/test/org/apache/solr/morphlines/solr/AbstractSolrMorphlineZkTestBase.java

@@ -25,6 +25,7 @@ import com.codahale.metrics.MetricRegistry;
 import com.google.common.collect.ListMultimap;
 import com.typesafe.config.Config;
 import org.apache.commons.io.FileUtils;
+import org.apache.lucene.util.Constants;
 import org.apache.solr.client.solrj.SolrServerException;
 import org.apache.solr.cloud.AbstractFullDistribZkTestBase;
 import org.apache.solr.cloud.AbstractZkTestCase;
@@ -63,6 +64,8 @@ public abstract class AbstractSolrMorphlineZkTestBase extends AbstractFullDistri
   
   @BeforeClass
   public static void setupClass() throws Exception {
+    assumeFalse("This test fails on Java 9 (https://issues.apache.org/jira/browse/SOLR-8876)", Constants.JRE_IS_MINIMUM_JAVA9);
+    
     assumeFalse("This test fails on UNIX with Turkish default locale (https://issues.apache.org/jira/browse/SOLR-6387)",
         new Locale("tr").getLanguage().equals(Locale.getDefault().getLanguage()));
     solrHomeDirectory = createTempDir().toFile();

solr/core/src/test/org/apache/solr/cloud/SaslZkACLProviderTest.java

@@ -56,6 +56,8 @@ public class SaslZkACLProviderTest extends SolrTestCaseJ4 {
 
   @BeforeClass
   public static void beforeClass() {
+    assumeFalse("FIXME: This test fails on Java 9 (https://issues.apache.org/jira/browse/SOLR-8052)", Constants.JRE_IS_MINIMUM_JAVA9);
+    
     assumeFalse("FIXME: SOLR-7040: This test fails under IBM J9",
                 Constants.JAVA_VENDOR.startsWith("IBM"));
     System.setProperty("solrcloud.skip.autorecovery", "true");

solr/core/src/test/org/apache/solr/cloud/TestCloudDeleteByQuery.java

@@ -19,6 +19,8 @@ package org.apache.solr.cloud;
 import java.io.File;
 import java.lang.invoke.MethodHandles;
 import java.net.URL;
+import java.nio.file.Path;
+import java.nio.file.Paths;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.HashMap;
@@ -91,10 +93,10 @@ public class TestCloudDeleteByQuery extends SolrCloudTestCase {
   private static void createMiniSolrCloudCluster() throws Exception {
     
     final String configName = "solrCloudCollectionConfig";
-    File configDir = new File(TEST_HOME() + File.separator + "collection1" + File.separator + "conf");
+    final Path configDir = Paths.get(TEST_HOME(), "collection1", "conf");
     
     configureCluster(NUM_SERVERS)
-      .addConfig(configName, configDir.toPath())
+      .addConfig(configName, configDir)
       .configure();
     
     Map<String, String> collectionProperties = new HashMap<>();

solr/core/src/test/org/apache/solr/core/TestImplicitCoreProperties.java

@@ -34,8 +34,10 @@ public class TestImplicitCoreProperties extends SolrTestCaseJ4 {
 
   @AfterClass
   public static void teardownContainer() {
-    if (cc != null)
+    if (cc != null) {
       cc.shutdown();
+    }
+    cc = null;
   }
 
   @Test

solr/core/src/test/org/apache/solr/handler/admin/CoreAdminCreateDiscoverTest.java

@@ -58,6 +58,7 @@ public class CoreAdminCreateDiscoverTest extends SolrTestCaseJ4 {
   @AfterClass
   public static void afterClass() throws Exception {
     admin = null; // Release it or the test harness complains.
+    solrHomeDirectory = null;
   }
 
   private static void setupCore(String coreName, boolean blivet) throws IOException {

solr/test-framework/src/java/org/apache/solr/SolrTestCaseJ4.java

@@ -265,6 +265,7 @@ public abstract class SolrTestCaseJ4 extends LuceneTestCase {
 
       // clean up static
       sslConfig = null;
+      testSolrHome = null;
     }
     
     IpTables.unblockAllPorts();

solr/test-framework/src/java/org/apache/solr/cloud/SolrCloudTestCase.java

@@ -150,8 +150,10 @@ public class SolrCloudTestCase extends SolrTestCaseJ4 {
 
   @AfterClass
   public static void shutdownCluster() throws Exception {
-    if (cluster != null)
+    if (cluster != null) {
       cluster.shutdown();
+    }
+    cluster = null;
   }
 
   @Before