bugfix not using know serializers when defined

[jogibear9988]

fix for #183

what is still a problem:

if we have two classes wich reference one another, the known type is not found on one, cause one of them is added later.

also the order of the adding of the classes is important:

for example, this will work:

    class Temp
    {
        public object[] SubArray { get; set; }
        public string aa { get; set; }
        public Dictionary<string,string> dc { get; set; }
    }

    [Fact]
    public void WritesManifestEvenIfKnown()
    {
        var stream = new MemoryStream();
        var msg = new Temp() { aa = "huhu", dc = new Dictionary<string, string>() { { "a", "b" } }, SubArray = new object[] { 1, (byte)2, new object[] { 3 } } };

        var serializer = new Serializer(new SerializerOptions(knownTypes: new[] { typeof(object[]), typeof(DictionaryEntry), typeof(Dictionary<string, string>), typeof(Temp),  }));


        serializer.Serialize(msg, stream);
        stream.Position = 0;
        var a = stream.ToArray();
        var q = string.Join(", ", a.Select(x => x.ToString()));
        var q2 = string.Join(", ", a.Select(x => ((char)x).ToString()));
        var res = serializer.Deserialize(stream);
    }

this not:

    [Fact]
    public void WritesManifestEvenIfKnown()
    {
        var stream = new MemoryStream();
        var msg = new Temp() { aa = "huhu", dc = new Dictionary<string, string>() { { "a", "b" } }, SubArray = new object[] { 1, (byte)2, new object[] { 3 } } };

        var serializer = new Serializer(new SerializerOptions(knownTypes: new[] { typeof(DictionaryEntry), typeof(Dictionary<string, string>), typeof(Temp), typeof(object[]),  }));


        serializer.Serialize(msg, stream);
        stream.Position = 0;
        var a = stream.ToArray();
        var q = string.Join(", ", a.Select(x => x.ToString()));
        var q2 = string.Join(", ", a.Select(x => ((char)x).ToString()));
        var res = serializer.Deserialize(stream);
    }

see changed order of types in the Serializer constructor

[jogibear9988]

@Aaronontheweb @Arkatufus
could you review?

[Aaronontheweb]

@jogibear9988 yessir, we will

[Aaronontheweb]

Yep, added @Arkatufus to this issue

[Arkatufus]

@jogibear9988
I'm sorry, but I couldn't understand the problem this PR is trying to solve, I tried both your code and the original code, both outputs the exact same binary output.

[Aaronontheweb]

@jogibear9988 if you could help explain the issue more clearly in terms of "expected" vs. "actual" behavior, we would appreciate it. Can't merge this change without fully grasping what it was trying to solve and how this works.

[jogibear9988]

Surely,

Look at my sample, where I said it is not workin.
Run it without my changes. The size is much bigger, cause the Serialized Data does contain the type information even if it should not, cause the types are in the knownTypes.

The apply my patch and the size is much smaller, cause the type info is now not serialized

[jogibear9988]

Any if you have circular references you could not fix this problem by changeing order of the knowntypes

[Arkatufus]

@jogibear9988
To be honest, I still can't see the difference.
Here are the resulting byte stream from both net461 and netcoreapp3.0 output, original and modified:

net461
Ori: fe 00 00 ff 20 00 00 00 53 79 73 74 65 6d 2e 4f 62 6a 65 63 74 5b 5d 2c 20 6d 73 63 6f 72 6c 69 62 2c 25 63 6f 72 65 25 03 00 00 00 08 01 00 00 00 08 02 00 00 00 08 03 00 00 00
Mod: fe 00 00 ff 20 00 00 00 53 79 73 74 65 6d 2e 4f 62 6a 65 63 74 5b 5d 2c 20 6d 73 63 6f 72 6c 69 62 2c 25 63 6f 72 65 25 03 00 00 00 08 01 00 00 00 08 02 00 00 00 08 03 00 00 00

netcoreapp3.0
Ori: fe 00 00 ff 2e 00 00 00 53 79 73 74 65 6d 2e 4f 62 6a 65 63 74 5b 5d 2c 20 53 79 73 74 65 6d 2e 50 72 69 76 61 74 65 2e 43 6f 72 65 4c 69 62 2c 25 63 6f 72 65 25 03 00 00 00 08 01 00 00 00 08 02 00 00 00 08 03 00 00 00
Mod: fe 00 00 ff 2e 00 00 00 53 79 73 74 65 6d 2e 4f 62 6a 65 63 74 5b 5d 2c 20 53 79 73 74 65 6d 2e 50 72 69 76 61 74 65 2e 43 6f 72 65 4c 69 62 2c 25 63 6f 72 65 25 03 00 00 00 08 01 00 00 00 08 02 00 00 00 08 03 00 00 00

Made using your original code as a reference:

[Fact]
public void WritesManifestEvenIfKnown()
{
    var stream = new MemoryStream();
    var msg = new Temp() { SubArray = new object[] { 1, 2, 3 } };
    var serializer = new Serializer(new SerializerOptions(knownTypes: new[] { typeof(Temp), typeof(object[]) }));
    serializer.Serialize(msg, stream);
    var bytes = stream.ToArray();
    stream.Position = 0;
    var res = serializer.Deserialize(stream);

    var sb = new StringBuilder();
    foreach (var b in bytes) {
        sb.Append($"{b:x2} ");
    }
    _output.WriteLine(sb.ToString());
}

As you can see, they are identical, so I can't really see the original problem

[jogibear9988]

@Arkatufus I've now attached a test wich fails if you revert the changes from my commit 6bafc4c

[Aaronontheweb]

Thanks @jogibear9988 !

[Arkatufus]

@jogibear9988
Can you merge this PR into your changes?
jogibear9988#1

I feel a lot safer if we remove all modified codes that can't be reached by unit testing.