public void testComplexWithShallowCycle() throws GraphConstraintException {
// +-----------+
// | |
// v |
// a --> b --> c
// | |
// | v
// +---> d
Dag dag = new Dag();
try {
dag.addEdge("a", "b");
dag.addEdge("b", "c");
dag.addEdge("b", "d");
dag.addEdge("a", "d");
dag.addEdge("c", "a");
fail("Cycle should be detected");
} catch (CycleDetectedException e) {
assertCycle(new String[] {"c", "a", "b", "c"}, e.getCycle());
// Ensure that edge was removed
assertFalse("Edge 'c' -> 'a' should have been removed.", dag.hasEdge("c", "a"));
}
}
public void testSimpleSelfCycle() throws GraphConstraintException {
// a --> b <---+
// | |
// | |
// +-----+
Dag dag = new Dag();
try {
dag.addEdge("a", "b");
dag.addEdge("b", "b");
fail("Cycle should be detected");
} catch (CycleDetectedException e) {
assertCycle(new String[] {"b", "b"}, e.getCycle());
// Ensure that edge was removed
assertFalse("Edge 'b' -> 'b' should have been removed.", dag.hasEdge("b", "b"));
}
}
public void testComplexWithDeepCycle() throws GraphConstraintException {
// f --> g --> h
// |
// |
// a --> b --> c --> d
// ^ |
// | v
// +---------- e
final Dag dag = new Dag();
try {
dag.addEdge("a", "b");
dag.addEdge("b", "c");
dag.addEdge("b", "f");
dag.addEdge("f", "g");
dag.addEdge("g", "h");
dag.addEdge("c", "d");
dag.addEdge("d", "e");
dag.addEdge("e", "b");
fail("Cycle should be detected");
} catch (CycleDetectedException e) {
assertCycle(new String[] {"e", "b", "c", "d", "e"}, e.getCycle());
// Ensure that edge was removed
assertFalse("Edge 'e' -> 'b' should have been removed.", dag.hasEdge("e", "b"));
}
}
