[RocksJava] RocksJava Testcases

- NativeLibraryLoader Test
- EnvironmentTest Bugfix

java/Makefile

@@ -74,6 +74,7 @@ JAVA_TESTS = org.rocksdb.BackupableDBOptionsTest\
 	org.rocksdb.MemTableTest\
 	org.rocksdb.MergeTest\
 	org.rocksdb.MixedOptionsTest\
+    org.rocksdb.NativeLibraryLoaderTest\
 	org.rocksdb.OptionsTest\
 	org.rocksdb.PlainTableConfigTest\
 	org.rocksdb.ReadOnlyTest\

java/src/test/java/org/rocksdb/NativeLibraryLoaderTest.java

@@ -0,0 +1,38 @@
+// Copyright (c) 2014, Facebook, Inc.  All rights reserved.
+// This source code is licensed under the BSD-style license found in the
+// LICENSE file in the root directory of this source tree. An additional grant
+// of patent rights can be found in the PATENTS file in the same directory.
+package org.rocksdb;
+
+import org.junit.ClassRule;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.TemporaryFolder;
+import org.rocksdb.util.Environment;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class NativeLibraryLoaderTest {
+
+  @ClassRule
+  public static final RocksMemoryResource rocksMemoryResource =
+      new RocksMemoryResource();
+
+  @Rule
+  public TemporaryFolder temporaryFolder = new TemporaryFolder();
+
+  @Test
+  public void tempFolder() throws IOException {
+    NativeLibraryLoader.getInstance().loadLibrary(
+        temporaryFolder.getRoot().getAbsolutePath());
+    Path path = Paths.get(temporaryFolder.getRoot().getAbsolutePath(),
+        Environment.getJniLibraryFileName("rocksdb"));
+    assertThat(Files.exists(path));
+    assertThat(Files.isReadable(path));
+  }
+}

java/src/test/java/org/rocksdb/util/EnvironmentTest.java

@@ -4,6 +4,8 @@
 // of patent rights can be found in the PATENTS file in the same directory.
 package org.rocksdb.util;
 
+import org.junit.AfterClass;
+import org.junit.BeforeClass;
 import org.junit.Test;
 
 import java.lang.reflect.Field;
@@ -12,10 +14,17 @@ import java.lang.reflect.Modifier;
 import static org.assertj.core.api.Assertions.assertThat;
 
 public class EnvironmentTest {
+  private final static String ARCH_FIELD_NAME = "ARCH";
+  private final static String OS_FIELD_NAME = "OS";
 
-  // Init static context
-  private static Environment environment =
-      new Environment();
+  private static String INITIAL_OS;
+  private static String INITIAL_ARCH;
+
+  @BeforeClass
+  public static void saveState() {
+    INITIAL_ARCH = getEnvironmentClassField(ARCH_FIELD_NAME);
+    INITIAL_OS = getEnvironmentClassField(OS_FIELD_NAME);
+  }
 
   @Test
   public void mac32() {
@@ -122,11 +131,31 @@ public class EnvironmentTest {
 
   private void setEnvironmentClassFields(String osName,
       String osArch) {
-    setEnvironmentClassField("OS", osName);
-    setEnvironmentClassField("ARCH", osArch);
+    setEnvironmentClassField(OS_FIELD_NAME, osName);
+    setEnvironmentClassField(ARCH_FIELD_NAME, osArch);
+  }
+
+  @AfterClass
+  public static void restoreState() {
+    setEnvironmentClassField(OS_FIELD_NAME, INITIAL_OS);
+    setEnvironmentClassField(ARCH_FIELD_NAME, INITIAL_ARCH);
+  }
+
+  private static String getEnvironmentClassField(String fieldName) {
+    final Field field;
+    try {
+      field = Environment.class.getDeclaredField(fieldName);
+      field.setAccessible(true);
+      final Field modifiersField = Field.class.getDeclaredField("modifiers");
+      modifiersField.setAccessible(true);
+      modifiersField.setInt(field, field.getModifiers() & ~Modifier.FINAL);
+      return (String)field.get(null);
+    } catch (NoSuchFieldException | IllegalAccessException e) {
+      throw new RuntimeException(e);
+    }
   }
 
-  private void setEnvironmentClassField(String fieldName, String value) {
+  private static void setEnvironmentClassField(String fieldName, String value) {
     final Field field;
     try {
       field = Environment.class.getDeclaredField(fieldName);