Fix unittest and update comment

flink/src/main/java/org/apache/zeppelin/flink/FlinkEnvironment.java

@@ -27,7 +27,8 @@ import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 /**
- *
+ * The class override execute() method to create an PlanExecutor with
+ * jar file that packages classes from scala compiler.
  */
 public class FlinkEnvironment extends ExecutionEnvironment {
   Logger logger = LoggerFactory.getLogger(FlinkEnvironment.class);
@@ -79,52 +80,4 @@ public class FlinkEnvironment extends ExecutionEnvironment {
 
     return jsonPlan;
   }
-
-/*
-  private File createJar() throws IOException {
-    // create execution environment
-    File jarFile = new File(System.getProperty("java.io.tmpdir")
-        + "/ZeppelinFlinkJar_" + System.currentTimeMillis() + ".jar");
-
-
-    File[] classFiles = classDir.listFiles();
-    if (classFiles == null) {
-      return null;
-    }
-
-    byte buffer[] = new byte[10240];
-    // Open archive file
-    FileOutputStream stream = new FileOutputStream(jarFile);
-    JarOutputStream out = new JarOutputStream(stream, new Manifest());
-
-    for (int i = 0; i < classFiles.length; i++) {
-      File classFile = classFiles[i];
-      if (classFiles == null || !classFile.exists()
-          || classFile.isDirectory())
-        continue;
-
-
-      // Add class
-      JarEntry jarAdd = new JarEntry(classFile.getName());
-      jarAdd.setTime(classFile.lastModified());
-      out.putNextEntry(jarAdd);
-      logger.info("add class {} into jar", classFile);
-
-      // Write file to archive
-      FileInputStream in = new FileInputStream(classFile);
-      while (true) {
-        int nRead = in.read(buffer, 0, buffer.length);
-        if (nRead <= 0)
-          break;
-        out.write(buffer, 0, nRead);
-      }
-      in.close();
-    }
-
-    out.close();
-    stream.close();
-    return jarFile;
-  }
-  */
-
 }

flink/src/main/java/org/apache/zeppelin/flink/FlinkIMain.java

@@ -17,6 +17,7 @@ import scala.tools.nsc.Settings;
 import scala.tools.nsc.interpreter.IMain;
 
 /**
+ * Scala compiler
  */
 public class FlinkIMain extends IMain {
   Logger logger = LoggerFactory.getLogger(FlinkIMain.class);

flink/src/main/java/org/apache/zeppelin/flink/JarHelper.java

@@ -11,6 +11,9 @@ import java.util.jar.JarInputStream;
 import java.util.jar.JarOutputStream;
 
 /**
+ * This class copied from flink-scala-shell. Once the flink-0.9 is published in
+ * the maven repository, this class can be removed
+ *
  * Provides utility services for jarring and unjarring files and directories.
  * Note that a given instance of JarHelper is not threadsafe with respect to
  * multiple jar operations.

flink/src/test/java/org/apache/zeppelin/flink/FlinkInterpreterTest.java

@@ -23,25 +23,26 @@ import java.util.Properties;
 
 import org.apache.zeppelin.interpreter.InterpreterContext;
 import org.apache.zeppelin.interpreter.InterpreterResult;
-import org.junit.After;
-import org.junit.Before;
+import org.apache.zeppelin.interpreter.InterpreterResult.Code;
+import org.junit.AfterClass;
+import org.junit.BeforeClass;
 import org.junit.Test;
 
 public class FlinkInterpreterTest {
 
-  private FlinkInterpreter flink;
-  private InterpreterContext context;
+  private static FlinkInterpreter flink;
+  private static InterpreterContext context;
 
-  @Before
-  public void setUp() {
+  @BeforeClass
+  public static void setUp() {
     Properties p = new Properties();
     flink = new FlinkInterpreter(p);
     flink.open();
     context = new InterpreterContext(null, null, null, null, null, null, null);
   }
 
-  @After
-  public void tearDown() {
+  @AfterClass
+  public static void tearDown() {
     flink.close();
     flink.destroy();
   }
@@ -53,12 +54,13 @@ public class FlinkInterpreterTest {
     assertEquals("1", result.message());
   }
 
+
   @Test
   public void testWordCount() {
     flink.interpret("val text = env.fromElements(\"To be or not to be\")", context);
     flink.interpret("val counts = text.flatMap { _.toLowerCase.split(\" \") }.map { (_, 1) }.groupBy(0).sum(1)", context);
     flink.interpret("counts.print()", context);
     InterpreterResult result = flink.interpret("env.execute(\"WordCount Example\")", context);
-    assertEquals("", result.message());
+    assertEquals(Code.SUCCESS, result.code());
   }
 }