azagrebin commented on a change in pull request #13205: URL: https://github.com/apache/flink/pull/13205#discussion_r475684085
########## File path: flink-runtime/src/test/java/org/apache/flink/runtime/executiongraph/failover/flip1/StronglyConnectedComponentsComputeUtilsTest.java ########## @@ -0,0 +1,216 @@ +/* + * 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.runtime.executiongraph.failover.flip1; + +import org.apache.flink.util.TestLogger; + +import org.junit.Test; + +import java.util.ArrayList; +import java.util.Arrays; +import java.util.Collections; +import java.util.HashSet; +import java.util.List; +import java.util.Random; +import java.util.Set; +import java.util.stream.Collectors; +import java.util.stream.IntStream; + +import static org.apache.flink.runtime.executiongraph.failover.flip1.StronglyConnectedComponentsComputeUtils.computeStronglyConnectedComponents; +import static org.hamcrest.Matchers.is; +import static org.junit.Assert.assertThat; + +/** + * Unit tests for {@link StronglyConnectedComponentsComputeUtils}. + */ +public class StronglyConnectedComponentsComputeUtilsTest extends TestLogger { + + @Test + public void testWithCycles() { + final List<List<Integer>> edges = Arrays.asList( + Arrays.asList(2, 3), + Arrays.asList(0), + Arrays.asList(1), + Arrays.asList(4), + Collections.emptyList()); + + final Set<Set<Integer>> result = computeStronglyConnectedComponents(5, edges); + + final Set<Set<Integer>> expected = new HashSet<>(); + expected.add(new HashSet<>(Arrays.asList(0, 1, 2))); + expected.add(Collections.singleton(3)); + expected.add(Collections.singleton(4)); + + assertThat(result, is(expected)); + } + + @Test + public void testWithMultipleCycles() { + final List<List<Integer>> edges = Arrays.asList( + Arrays.asList(1), + Arrays.asList(2), + Arrays.asList(0), + Arrays.asList(1, 2, 4), + Arrays.asList(3, 5), + Arrays.asList(2, 6), + Arrays.asList(5), + Arrays.asList(4, 6, 7)); + + final Set<Set<Integer>> result = computeStronglyConnectedComponents(8, edges); + + final Set<Set<Integer>> expected = new HashSet<>(); + expected.add(new HashSet<>(Arrays.asList(0, 1, 2))); + expected.add(new HashSet<>(Arrays.asList(3, 4))); + expected.add(new HashSet<>(Arrays.asList(5, 6))); + expected.add(Collections.singleton(7)); + + assertThat(result, is(expected)); + } + + @Test + public void testWithConnectedCycles() { + final List<List<Integer>> edges = Arrays.asList( + Arrays.asList(1), + Arrays.asList(2, 4, 5), + Arrays.asList(3, 6), + Arrays.asList(2, 7), + Arrays.asList(0, 5), + Arrays.asList(6), + Arrays.asList(5), + Arrays.asList(3, 6)); + + final Set<Set<Integer>> result = computeStronglyConnectedComponents(8, edges); + + final Set<Set<Integer>> expected = new HashSet<>(); + expected.add(new HashSet<>(Arrays.asList(0, 1, 4))); + expected.add(new HashSet<>(Arrays.asList(2, 3, 7))); + expected.add(new HashSet<>(Arrays.asList(5, 6))); + + assertThat(result, is(expected)); + } + + @Test + public void testWithNoEdge() { + final List<List<Integer>> edges = Arrays.asList( + Collections.emptyList(), + Collections.emptyList(), + Collections.emptyList(), + Collections.emptyList(), + Collections.emptyList()); + + final Set<Set<Integer>> result = computeStronglyConnectedComponents(5, edges); + + final Set<Set<Integer>> expected = new HashSet<>(); + expected.add(Collections.singleton(0)); + expected.add(Collections.singleton(1)); + expected.add(Collections.singleton(2)); + expected.add(Collections.singleton(3)); + expected.add(Collections.singleton(4)); + + assertThat(result, is(expected)); + } + + @Test + public void testWithNoCycle() { + final List<List<Integer>> edges = Arrays.asList( + Arrays.asList(1), + Arrays.asList(2), + Arrays.asList(3), + Arrays.asList(4), + Collections.emptyList()); + + final Set<Set<Integer>> result = computeStronglyConnectedComponents(5, edges); + + final Set<Set<Integer>> expected = new HashSet<>(); + expected.add(Collections.singleton(0)); + expected.add(Collections.singleton(1)); + expected.add(Collections.singleton(2)); + expected.add(Collections.singleton(3)); + expected.add(Collections.singleton(4)); + + assertThat(result, is(expected)); + } + + @Test + public void testLargeGraph() { + final int n = 100000; + final List<List<Integer>> edges = new ArrayList<>(); + for (int i = 0; i < n; i++) { + edges.add(Collections.singletonList((i + 1) % n)); + } + + final Set<Set<Integer>> result = computeStronglyConnectedComponents(n, edges); + + final Set<Integer> singleComponent = IntStream.range(0, n).boxed().collect(Collectors.toSet()); + + assertThat(result, is(Collections.singleton(singleComponent))); + } + + @Test + public void testArbitraryGraph() { Review comment: My concern was the complexity of the test to maintain in the code base. I think it is good to try this kind of test once but It seems to me that the random tests are usually hard to maintain and it is better to cover with the deterministic cases. I leave it up to you whether to keep it. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org
