public void TestFieldPresence()
{
// Optional non-message fields set to their default value are treated the same
// way as not set.
// Serialization will ignore such fields.
TestAllTypes.Builder builder = TestAllTypes.CreateBuilder();
builder.SetOptionalInt32(0);
builder.SetOptionalString("");
builder.SetOptionalBytes(ByteString.Empty);
builder.SetOptionalNestedEnum(TestAllTypes.Types.NestedEnum.FOO);
TestAllTypes message = builder.Build();
Assert.AreEqual(0, message.SerializedSize);
// Test merge
TestAllTypes.Builder a = TestAllTypes.CreateBuilder();
a.SetOptionalInt32(1);
a.SetOptionalString("x");
a.SetOptionalBytes(ByteString.CopyFromUtf8("y"));
a.SetOptionalNestedEnum(TestAllTypes.Types.NestedEnum.BAR);
a.MergeFrom(message);
TestAllTypes messageA = a.Build();
Assert.AreEqual(1, messageA.OptionalInt32);
Assert.AreEqual("x", messageA.OptionalString);
Assert.AreEqual(ByteString.CopyFromUtf8("y"), messageA.OptionalBytes);
Assert.AreEqual(TestAllTypes.Types.NestedEnum.BAR, messageA.OptionalNestedEnum);
// equals/hashCode should produce the same results
TestAllTypes empty = TestAllTypes.CreateBuilder().Build();
Assert.IsTrue(empty.Equals(message));
Assert.IsTrue(message.Equals(empty));
Assert.AreEqual(empty.GetHashCode(), message.GetHashCode());
}