Github user tzulitai commented on a diff in the pull request:
https://github.com/apache/flink/pull/5116#discussion_r156233639
--- Diff:
flink-connectors/flink-connector-kafka-base/src/test/java/org/apache/flink/streaming/connectors/kafka/FlinkRoundRobinPartitionerTest.java
---
@@ -0,0 +1,118 @@
+/*
+ * 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.flink.streaming.connectors.kafka;
+
+import
org.apache.flink.streaming.connectors.kafka.partitioner.FlinkRoundRobinPartitioner;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+/**
+ * Tests for the {@link FlinkRoundRobinPartitioner}.
+ */
+public class FlinkRoundRobinPartitionerTest {
+ /**
+ * Test for when there are more sinks than partitions.
+ * <pre>
+ * Flink Sinks: Kafka Partitions
+ * 1 ----------------> 1
+ * 2 --------------/
+ * 3 -------------/
+ * 4 ------------/
+ * </pre>
+ */
+ @Test
+ public void testMoreFlinkThanPartitions() {
+ FlinkRoundRobinPartitioner<String> part = new
FlinkRoundRobinPartitioner<>();
+
+ int[] partitions = new int[]{0};
+
+ part.open(0, 4);
+ Assert.assertEquals(0, part.partition("abc1", null, null, null,
partitions));
+
+ part.open(1, 4);
+ Assert.assertEquals(0, part.partition("abc2", null, null, null,
partitions));
+
+ part.open(2, 4);
+ Assert.assertEquals(0, part.partition("abc3", null, null, null,
partitions));
+ Assert.assertEquals(0, part.partition("abc3", null, null, null,
partitions)); // check if it is changing ;)
+
+ part.open(3, 4);
+ Assert.assertEquals(0, part.partition("abc4", null, null, null,
partitions));
+ }
+
+ /**
+ * Tests for when there are more partitions than sinks.
+ * <pre>
+ * Flink Sinks: Kafka Partitions
+ * 1 ----------------> 1
+ * 2 ----------------> 2
+ *
3
+ *
4
+ *
5
+ *
+ * </pre>
+ */
+ @Test
+ public void testFewerFlinkThanPartitions() {
+ FlinkRoundRobinPartitioner<String> part = new
FlinkRoundRobinPartitioner<>();
+
+ int[] partitions = new int[]{0, 1, 2, 3, 4};
+ part.open(0, 2);
+ Assert.assertEquals(0, part.partition("abc1", null, null, null,
partitions));
+ Assert.assertEquals(1, part.partition("abc1", null, null, null,
partitions));
+ Assert.assertEquals(2, part.partition("abc1", null, null, null,
partitions));
+ Assert.assertEquals(3, part.partition("abc1", null, null, null,
partitions));
+ Assert.assertEquals(4, part.partition("abc1", null, null, null,
partitions));
+
+ part.open(1, 2);
+ Assert.assertEquals(1, part.partition("abc1", null, null, null,
partitions));
+ Assert.assertEquals(2, part.partition("abc1", null, null, null,
partitions));
+ Assert.assertEquals(3, part.partition("abc1", null, null, null,
partitions));
+ Assert.assertEquals(4, part.partition("abc1", null, null, null,
partitions));
+ Assert.assertEquals(0, part.partition("abc1", null, null, null,
partitions));
+ }
+
+ /*
+ * Flink Sinks: Kafka Partitions
+ * 1 ------------>---> 1
+ * 2 -----------/----> 2
+ * 3 ----------/
+ */
+ @Test
+ public void testMixedCase() {
+ FlinkRoundRobinPartitioner<String> part = new
FlinkRoundRobinPartitioner<>();
+ int[] partitions = new int[]{0, 1};
+
+ part.open(0, 3);
+ Assert.assertEquals(0, part.partition("abc1", null, null, null,
partitions));
+ Assert.assertEquals(1, part.partition("abc1", null, null, null,
partitions));
+ Assert.assertEquals(0, part.partition("abc1", null, null, null,
partitions));
+
+ part.open(1, 3);
+ Assert.assertEquals(1, part.partition("abc1", null, null, null,
partitions));
+ Assert.assertEquals(0, part.partition("abc1", null, null, null,
partitions));
+ Assert.assertEquals(1, part.partition("abc1", null, null, null,
partitions));
+
+ part.open(2, 3);
+ Assert.assertEquals(0, part.partition("abc1", null, null, null,
partitions));
+ Assert.assertEquals(1, part.partition("abc1", null, null, null,
partitions));
+ Assert.assertEquals(0, part.partition("abc1", null, null, null,
partitions));
+
--- End diff --
nit: unnecessary empty line.
---
