See about cross-version serialization issues from the CLR2 assembly t…

…hat appeared on AppVeyor

  -- also learn that type Derived() = inherit Base() gets construction implemented as a suspicious recursive call

AltCover.Runner/Runner.fs

@@ -13,6 +13,11 @@ open Augment
 [<System.Diagnostics.CodeAnalysis.ExcludeFromCodeCoverage>]
 type Tracer = { Tracer : string }
 
+type MonoTypeBinder (``type``:Type) =
+  inherit System.Runtime.Serialization.SerializationBinder()
+  override self.BindToType (_:string, _:string) =
+    ``type``
+
 module Runner =
 
   let mutable internal recordingDirectory : Option<string> = None
@@ -109,6 +114,7 @@ module Runner =
 
       use results = File.OpenRead(binpath)
       let formatter = System.Runtime.Serialization.Formatters.Binary.BinaryFormatter()
+      formatter.Binder <- MonoTypeBinder(typeof<(string*int)>) // anything else is an error
 
       let rec sink() = try
                           let hit = formatter.Deserialize(results) :?> (string*int)

Shadow.Tests/Tracer.fs

@@ -24,6 +24,11 @@ open System.Reflection
 open AltCover.Recorder
 open NUnit.Framework
 
+type UpdateBinder () =
+  inherit System.Runtime.Serialization.SerializationBinder()
+  override self.BindToType (_:string, _:string) =
+    typeof<(string*int)> // anything else is an error
+
 [<TestFixture>]
 type AltCoverCoreTests() = class
 
@@ -56,6 +61,7 @@ type AltCoverCoreTests() = class
   member self.ReadResults (stream:Stream) =
     let hits = List<(string*int)>()
     let formatter = System.Runtime.Serialization.Formatters.Binary.BinaryFormatter()
+    formatter.Binder <- UpdateBinder()
     let rec sink() = try
                           let hit = formatter.Deserialize(stream) :?> (string*int)
                           hit |> hits.Add