NIFI-1684 fixed NPE, added tests

Signed-off-by: joewitt <joewitt@apache.org>

nifi-nar-bundles/nifi-kafka-bundle/nifi-kafka-processors/src/main/java/org/apache/nifi/processors/kafka/SplittableMessageContext.java

@@ -46,6 +46,9 @@ final class SplittableMessageContext {
      *            - "(\\W)\\Z".
      */
     SplittableMessageContext(String topicName, byte[] keyBytes, String delimiterPattern) {
+        if (topicName == null || topicName.trim().length() == 0){
+            throw new IllegalArgumentException("'topicName' must not be null or empty");
+        }
         this.topicName = topicName;
         this.keyBytes = keyBytes;
         this.delimiterPattern = delimiterPattern != null ? delimiterPattern : "(\\W)\\Z";
@@ -60,21 +63,26 @@ final class SplittableMessageContext {
     }
 
     /**
-     *
+     * Will set failed segments from an array of integers
      */
     void setFailedSegments(int... failedSegments) {
+        if (failedSegments != null) {
             this.failedSegments = new BitSet();
             for (int failedSegment : failedSegments) {
                 this.failedSegments.set(failedSegment);
             }
         }
+    }
 
     /**
-     *
+     * Will set failed segments from an array of bytes that will be used to
+     * construct the final {@link BitSet} representing failed segments
      */
     void setFailedSegmentsAsByteArray(byte[] failedSegments) {
+        if (failedSegments != null) {
             this.failedSegments = BitSet.valueOf(failedSegments);
         }
+    }
 
     /**
      * Returns the list of integers representing the segments (chunks) of the
@@ -102,7 +110,7 @@ final class SplittableMessageContext {
      * Returns the key bytes as String
      */
     String getKeyBytesAsString() {
-        return new String(this.keyBytes);
+        return this.keyBytes != null ? new String(this.keyBytes) : null;
     }
 
     /**

nifi-nar-bundles/nifi-kafka-bundle/nifi-kafka-processors/src/test/java/org/apache/nifi/processors/kafka/SplittableMessageContextTest.java

@@ -0,0 +1,64 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.nifi.processors.kafka;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNull;
+
+import java.nio.charset.StandardCharsets;
+
+import org.junit.Test;
+
+public class SplittableMessageContextTest {
+
+    @Test(expected = IllegalArgumentException.class)
+    public void failNullEmptyTopic() {
+        new SplittableMessageContext(null, null, null);
+    }
+
+    @Test
+    public void validateFullSetting() {
+        SplittableMessageContext ctx = new SplittableMessageContext("foo", "hello".getBytes(), "\n");
+        ctx.setFailedSegments(1, 3, 6);
+        assertEquals("\n", ctx.getDelimiterPattern());
+        assertEquals("hello", new String(ctx.getKeyBytes(), StandardCharsets.UTF_8));
+        assertEquals("foo", ctx.getTopicName());
+        assertEquals("topic: 'foo'; delimiter: '\n'", ctx.toString());
+    }
+
+
+    @Test
+    public void validateToString() {
+        SplittableMessageContext ctx = new SplittableMessageContext("foo", null, null);
+        assertEquals("topic: 'foo'; delimiter: '(\\W)\\Z'", ctx.toString());
+    }
+
+    @Test
+    public void validateNoNPEandNoSideffectsOnSetsGets() {
+        SplittableMessageContext ctx = new SplittableMessageContext("foo", null, null);
+        ctx.setFailedSegments(null);
+        assertNull(ctx.getFailedSegments());
+
+        ctx.setFailedSegmentsAsByteArray(null);
+        assertNull(ctx.getFailedSegments());
+
+        assertEquals("(\\W)\\Z", ctx.getDelimiterPattern());;
+        assertNull(ctx.getKeyBytes());
+        assertNull(ctx.getKeyBytesAsString());
+        assertEquals("foo", ctx.getTopicName());
+    }
+}