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/*
* Copyright 2019 Oath Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
*/
package com.yahoo.container.di.componentgraph.cycle;
import org.junit.Test;
import static com.yahoo.container.di.componentgraph.cycle.CycleFinderTest.Vertices.A;
import static com.yahoo.container.di.componentgraph.cycle.CycleFinderTest.Vertices.B;
import static com.yahoo.container.di.componentgraph.cycle.CycleFinderTest.Vertices.C;
import static com.yahoo.container.di.componentgraph.cycle.CycleFinderTest.Vertices.D;
import static org.hamcrest.Matchers.contains;
import static org.hamcrest.Matchers.empty;
import static org.junit.Assert.assertThat;
/**
* @author gjoranv
*/
public class CycleFinderTest {
enum Vertices {A, B, C, D}
@Test
public void graph_without_cycles_returns_no_cycle() {
var graph = new Graph<Vertices>();
graph.edge(A, B);
graph.edge(B, C);
graph.edge(A, C);
graph.edge(D, A);
var cycleFinder = new CycleFinder<>(graph);
assertThat(cycleFinder.findCycle(), empty());
}
@Test
public void graph_with_cycle_returns_cycle() {
var graph = new Graph<Vertices>();
graph.edge(A, B);
graph.edge(B, C);
graph.edge(C, A);
var cycleFinder = new CycleFinder<>(graph);
assertThat(cycleFinder.findCycle(), contains(A, B, C, A));
}
@Test
public void graph_with_self_referencing_vertex_returns_cycle() {
var graph = new Graph<Vertices>();
graph.edge(A, A);
var cycleFinder = new CycleFinder<>(graph);
assertThat(cycleFinder.findCycle(), contains(A, A));
}
@Test
public void leading_nodes_are_stripped_from_cycle() {
var graph = new Graph<Vertices>();
graph.edge(A, B);
graph.edge(B, C);
graph.edge(C, B);
var cycleFinder = new CycleFinder<>(graph);
assertThat(cycleFinder.findCycle(), contains(B, C, B));
}
@Test
public void findCycle_is_idempotent_with_cycle() {
var graph = new Graph<Vertices>();
graph.edge(A, A);
var cycleFinder = new CycleFinder<>(graph);
assertThat(cycleFinder.findCycle(), contains(A, A));
assertThat(cycleFinder.findCycle(), contains(A, A));
}
@Test
public void findCycle_is_idempotent_without_cycle() {
var graph = new Graph<Vertices>();
graph.edge(A, B);
var cycleFinder = new CycleFinder<>(graph);
assertThat(cycleFinder.findCycle(), empty());
assertThat(cycleFinder.findCycle(), empty());
}
}
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