/// <summary>
/// Tests a simple relation read/write operation.
/// </summary>
/// <param name="cache"></param>
public void DoOsmDataCacheTestRelation(OsmDataCache cache)
{
Relation relation = Relation.Create(1, new TagsCollection(
Tag.Create("relation", "yes")), RelationMember.Create(1, "something", OsmGeoType.Node));
// test invalid stuff.
Assert.Throws <ArgumentNullException>(() => cache.AddRelation(null));
Assert.Throws <Exception>(() => cache.AddRelation(new Relation()));
Assert.IsNull(cache.GetRelation(relation.Id.Value));
cache.AddRelation(relation);
Assert.IsTrue(cache.ContainsRelation(relation.Id.Value));
Relation readRelation = cache.GetRelation(relation.Id.Value);
Assert.IsNotNull(readRelation);
Assert.AreEqual(1, readRelation.Id.Value);
Assert.IsNotNull(relation.Tags);
Assert.AreEqual(1, relation.Tags.Count);
Assert.AreEqual("yes", relation.Tags["relation"]);
Assert.IsTrue(cache.TryGetRelation(relation.Id.Value, out readRelation));
Assert.IsNotNull(readRelation);
Assert.AreEqual(1, readRelation.Id.Value);
Assert.IsNotNull(relation.Tags);
Assert.AreEqual(1, relation.Tags.Count);
Assert.AreEqual("yes", relation.Tags["relation"]);
Assert.IsTrue(cache.RemoveRelation(relation.Id.Value));
Assert.IsFalse(cache.ContainsRelation(relation.Id.Value));
Assert.IsFalse(cache.RemoveRelation(relation.Id.Value));
}