private static void checkAnnotations(Graph<String, String> graph, Annotatable a, Annotatable b) {
final Annotation A = new Annotation() {};
final Annotation B = new Annotation() {};
// Initially null.
assertNull(a.getAnnotation());
assertNull(b.getAnnotation());
// Test basic setting.
a.setAnnotation(A);
b.setAnnotation(B);
assertSame(A, a.getAnnotation());
assertSame(B, b.getAnnotation());
// Test clearing.
graph.clearEdgeAnnotations();
graph.clearNodeAnnotations();
assertNull(a.getAnnotation());
assertNull(b.getAnnotation());
a.setAnnotation(A);
b.setAnnotation(B);
// Pushing clears.
graph.pushEdgeAnnotations();
graph.pushNodeAnnotations();
assertNull(a.getAnnotation());
assertNull(b.getAnnotation());
a.setAnnotation(B);
b.setAnnotation(B);
graph.pushEdgeAnnotations();
graph.pushNodeAnnotations();
a.setAnnotation(B);
b.setAnnotation(A);
// Test restoring then restoring old values with pop.
assertSame(B, a.getAnnotation());
assertSame(A, b.getAnnotation());
graph.popEdgeAnnotations();
graph.popNodeAnnotations();
assertSame(B, a.getAnnotation());
assertSame(B, b.getAnnotation());
graph.popEdgeAnnotations();
graph.popNodeAnnotations();
assertSame(A, a.getAnnotation());
assertSame(B, b.getAnnotation());
}
