@Test
public void testClear() {

	this.set.clear();
	assertTrue("Even after clear the set wasn't empty.", this.set.isEmpty());
	assertTrue("Empty set should allow a before a, but doesn't.", !this.set.allowsABeforeB(A, A));
	assertTrue("Empty set should allow a before b, but doesn't.", this.set.allowsABeforeB(A, B));
	assertTrue("Empty set should allow a before c, but doesn't.", this.set.allowsABeforeB(A, C));
	assertTrue("Empty set should allow a before d, but doesn't.", this.set.allowsABeforeB(A, D));
	assertTrue("Empty set should allow b before a, but doesn't.", this.set.allowsABeforeB(B, A));
	assertTrue("Empty set should allow b before b, but doesn't.", !this.set.allowsABeforeB(B, B));
	assertTrue("Empty set should allow b before c, but doesn't.", this.set.allowsABeforeB(B, C));
	assertTrue("Empty set should allow b before d, but doesn't.", this.set.allowsABeforeB(B, D));
	assertTrue("Empty set should allow c before a, but doesn't.", this.set.allowsABeforeB(C, A));
	assertTrue("Empty set should allow c before b, but doesn't.", this.set.allowsABeforeB(C, B));
	assertTrue("Empty set should allow c before c, but doesn't.", !this.set.allowsABeforeB(C, C));
	assertTrue("Empty set should allow c before d, but doesn't.", this.set.allowsABeforeB(C, D));
	assertTrue("Empty set should allow d before a, but doesn't.", this.set.allowsABeforeB(D, A));
	assertTrue("Empty set should allow d before b, but doesn't.", this.set.allowsABeforeB(D, B));
	assertTrue("Empty set should allow d before c, but doesn't.", this.set.allowsABeforeB(D, C));
	assertTrue("Empty set should allow d before d, but doesn't.", !this.set.allowsABeforeB(D, D));
}