/*
* Copyright 2016-present Facebook, Inc.
*
* Licensed 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 com.facebook.buck.graph;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertTrue;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableSet;
import java.util.List;
import org.junit.Test;
public class TopologicalSortTest {
// A
// / \
// B C
// / / \
// D __/ E
// / \ /
// F G
//
// Nodes and edges are added in weird orders to avoid default insertion orders happening to be
// sorted.
private DirectedAcyclicGraph<String> makeGraph() {
MutableDirectedGraph<String> graph = new MutableDirectedGraph<>();
graph.addNode("C");
graph.addNode("B");
graph.addNode("E");
graph.addNode("A");
graph.addNode("F");
graph.addNode("G");
graph.addNode("D");
graph.addEdge("D", "G");
graph.addEdge("A", "C");
graph.addEdge("D", "F");
graph.addEdge("B", "D");
graph.addEdge("A", "B");
graph.addEdge("C", "E");
graph.addEdge("C", "G");
return new DirectedAcyclicGraph<>(graph);
}
@Test
public void sorts() {
DirectedAcyclicGraph<String> graph = makeGraph();
ImmutableList<String> sorted = TopologicalSort.sort(graph);
assertEquals(graph.getNodes(), ImmutableSet.copyOf(sorted));
assertOrdering(sorted, "B", "A");
assertOrdering(sorted, "C", "A");
assertOrdering(sorted, "D", "B");
assertOrdering(sorted, "E", "C");
assertOrdering(sorted, "F", "D");
assertOrdering(sorted, "G", "C");
assertOrdering(sorted, "G", "D");
}
private <T> void assertOrdering(List<T> list, T before, T after) {
assertTrue(
String.format("Expected %s to be before %s in %s", before, after, list),
list.indexOf(before) < list.indexOf(after));
}
}