flink-java8/src/test/java/org/apache/flink/test/api/java/operators/lambdas/AllGroupReduceITCase.java

/**
 * 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.test.api.java.operators.lambdas;

import org.apache.flink.api.java.DataSet;
import org.apache.flink.api.java.ExecutionEnvironment;
import org.apache.flink.test.util.JavaProgramTestBase;

/**
 * IT cases for lambda allreduce functions.
 */
public class AllGroupReduceITCase extends JavaProgramTestBase {

	private static final String EXPECTED_RESULT = "aaabacad\n";

	private String resultPath;

	@Override
	protected void preSubmit() throws Exception {
		resultPath = getTempDirPath("result");
	}

	@Override
	protected void testProgram() throws Exception {
		final ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();

		DataSet<String> stringDs = env.fromElements("aa", "ab", "ac", "ad");
		DataSet<String> concatDs = stringDs.reduceGroup((values, out) -> {
			String conc = "";
			for (String s : values) {
				conc = conc.concat(s);
			}
			out.collect(conc);
		});
		concatDs.writeAsText(resultPath);
		env.execute();
	}

	@Override
	protected void postSubmit() throws Exception {
		compareResultsByLinesInMemory(EXPECTED_RESULT, resultPath);
	}
}