Backend(,Tests): stop using binary serialization

We had a need in the past to serialize exceptions (as they could
happen in off-line mode, when running as a cold-storage device),
so that they could be reported later when the device comes
online, but exceptions can't be seralizated to JSON (as
explained in [1]), so we ended up using binary serialization
(hooking it up in this past commit[2]).

However, binary serialization is going away in .NET9[3] because
of its potential security risk. Even though we doubt that for
our use case we would be affected by this security vector, we:
- Want to be prepared for the future.
- Know that there were anyway edge cases where binary
serialization was not actually working (e.g. see bug 240), and
was causing crashes.

We explored the idea of contributing an IException interface to
the 'sentry-dotnet' repo [4] (this library is the replacement of
SharpRaven, see [5]), so that we can serialize exceptions easily
in JSON, for later deserializing them and send them straight to
Sentry's API for report purposes, however:
* We found adding the IException overloads to be extremely
complicated due to the sheer amount of unit tests and things
that Sentry has, that would need to be modified.
* Given the above, we thought it would be too much work, and too
much risk of not being accepted upstream.
* Even if the IException overloads were accepted, the approach
would still be a leaky abstraction because the type of the
exception cannot be properly represented in a hypothetical
IException's property, so we were/would ending up with hacky
things such as an IsAggregateException:bool property, for
example. But why end here and not have more bool types for
other exceptions?

Instead of the above nightmare we have decided to go for the
simplest approach of all (the one that I should have done 3ish
years ago when I was initially solving this problem, to avoid
any OVERENGINEERING): just use good old Exception.ToString()
method! This method provides, not only the type of the
exception and its .Message property, also all its inner
exceptions recursively. This is GOOD ENOUGH.

Fixes #240
Closes https://gitlab.com/nblockchain/geewallet/-/issues/174

[1] 403d5c7
[2] 1f7b3b7
[3] https://twitter.com/SitnikAdam/status/1746874459640811575
[4] https://github.com/getsentry/sentry-dotnet
[5] #252

src/GWallet.Backend.Tests/ExceptionMarshalling.fs

@@ -1,14 +1,13 @@
 namespace GWallet.Backend.Tests
 
 open System
-open System.Runtime.Serialization
 
 open NUnit.Framework
 
 open GWallet.Backend
 
 
-type CustomExceptionWithoutSerializationCtor =
+type CustomExceptionWithoutInnerExceptionCtor =
    inherit Exception
 
    new(message) =
@@ -17,8 +16,6 @@ type CustomExceptionWithoutSerializationCtor =
 type CustomException =
    inherit Exception
 
-   new(info: SerializationInfo, context: StreamingContext) =
-       { inherit Exception(info, context) }
    new(message: string, innerException: CustomException) =
        { inherit Exception(message, innerException) }
    new(message) =
@@ -68,17 +65,17 @@ type ExceptionMarshalling () =
                 cex
         Marshalling.Serialize ex
 
-    let msg = "Exceptions didn't match. Full binary form was "
+    let msg = "Expected Exception.ToString() differs from actual"
 #if LEGACY_FRAMEWORK
-    let legacyMsg = "(Legacy)Exceptions didn't match. Full binary form was "
+    let legacyIgnoreMsg = "Mono or old .NETFramework might vary slightly; there's no need to really do any regression testing here"
 #endif
 
     [<Test>]
     member __.``can serialize basic exceptions``() =
         let json = SerializeBasicException ()
         Assert.That(json, Is.Not.Null)
-        Assert.That(json, Is.Not.Empty)
-        Assert.That(MarshallingData.SerializedExceptionsAreSame json MarshallingData.BasicExceptionExampleInJson false msg)
+        Assert.That(json.Trim(), Is.Not.Empty)
+        Assert.That(MarshallingData.SerializedExceptionsAreSame json MarshallingData.BasicExceptionExampleInJson msg)
 
     [<Test>]
     member __.``can deserialize basic exceptions``() =
@@ -90,31 +87,24 @@ type ExceptionMarshalling () =
                 Assert.Inconclusive "Fix the serialization test first"
                 failwith "unreachable"
 
-        let ex: Exception = Marshalling.Deserialize basicExSerialized
+        let ex: MarshalledException = Marshalling.Deserialize basicExSerialized
         Assert.That(ex, Is.Not.Null)
-        Assert.That(ex, Is.InstanceOf<Exception>())
-        Assert.That(ex.Message, Is.EqualTo "msg")
-        Assert.That(ex.InnerException, Is.Null)
-        Assert.That(ex.StackTrace, Is.Null)
+        Assert.That(ex, Is.InstanceOf<MarshalledException>())
+        Assert.That(ex.FullDescription.Trim().Length, Is.GreaterThan 0)
+        Assert.That(
+            MarshallingData.Sanitize ex.FullDescription,
+            Is.EqualTo (MarshallingData.Sanitize "System.Exception: msg")
+        )
 
     [<Test>]
     member __.``can serialize real exceptions``() =
         let json = SerializeRealException ()
         Assert.That(json, Is.Not.Null)
-        Assert.That(json, Is.Not.Empty)
+        Assert.That(json.Trim(), Is.Not.Empty)
 #if !LEGACY_FRAMEWORK
-        Assert.That(MarshallingData.SerializedExceptionsAreSame json MarshallingData.RealExceptionExampleInJson false msg)
+        Assert.That(MarshallingData.SerializedExceptionsAreSame json MarshallingData.RealExceptionExampleInJson msg)
 #else
-        if Config.IsWindowsPlatform () then
-            let serializedExceptionsAreSame =
-                try
-                    MarshallingData.SerializedExceptionsAreSame json MarshallingData.RealExceptionExampleInJson false msg
-                with
-                | :? AssertionException ->
-                    MarshallingData.SerializedExceptionsAreSame json MarshallingData.RealExceptionWindowsLegacyExampleInJson false legacyMsg
-            Assert.That serializedExceptionsAreSame
-        else
-            Assert.That(MarshallingData.SerializedExceptionsAreSame json MarshallingData.RealExceptionUnixLegacyExampleInJson false legacyMsg)
+        Assert.Ignore legacyIgnoreMsg
 #endif
 
     [<Test>]
@@ -127,20 +117,29 @@ type ExceptionMarshalling () =
                 Assert.Inconclusive "Fix the serialization test first"
                 failwith "unreachable"
 
-        let ex: Exception = Marshalling.Deserialize realExceptionSerialized
+        let ex: MarshalledException = Marshalling.Deserialize realExceptionSerialized
         Assert.That(ex, Is.Not.Null)
-        Assert.That(ex, Is.InstanceOf<Exception>())
-        Assert.That(ex.Message, Is.EqualTo "msg")
-        Assert.That(ex.InnerException, Is.Null)
-        Assert.That(ex.StackTrace, Is.Not.Null)
-        Assert.That(ex.StackTrace, Is.Not.Empty)
+        Assert.That(ex, Is.InstanceOf<MarshalledException>())
+        Assert.That(ex.FullDescription.Trim().Length, Is.GreaterThan 0)
+#if !LEGACY_FRAMEWORK
+        let expected =
+            sprintf
+                "System.Exception: msg   at GWallet.Backend.Tests.ExceptionMarshalling.SerializeRealException() in %s/ExceptionMarshalling.fs:line 38"
+                MarshallingData.ThisProjPath
+        Assert.That(
+            MarshallingData.Sanitize ex.FullDescription,
+            Is.EqualTo (MarshallingData.Sanitize expected)
+        )
+#else
+        Assert.Ignore legacyIgnoreMsg
+#endif
 
     [<Test>]
     member __.``can serialize inner exceptions``() =
         let json = SerializeInnerException ()
         Assert.That(json, Is.Not.Null)
-        Assert.That(json, Is.Not.Empty)
-        Assert.That(MarshallingData.SerializedExceptionsAreSame json MarshallingData.InnerExceptionExampleInJson false msg)
+        Assert.That(json.Trim(), Is.Not.Empty)
+        Assert.That(MarshallingData.SerializedExceptionsAreSame json MarshallingData.InnerExceptionExampleInJson msg)
 
     [<Test>]
     member __.``can deserialize inner exceptions``() =
@@ -152,31 +151,28 @@ type ExceptionMarshalling () =
                 Assert.Inconclusive "Fix the serialization test first"
                 failwith "unreachable"
 
-        let ex: Exception = Marshalling.Deserialize innerExceptionSerialized
+        let ex: MarshalledException = Marshalling.Deserialize innerExceptionSerialized
         Assert.That (ex, Is.Not.Null)
-        Assert.That (ex, Is.InstanceOf<Exception>())
-        Assert.That (ex.Message, Is.EqualTo "msg")
-        Assert.That (ex.StackTrace, Is.Null)
-        Assert.That (ex.InnerException, Is.Not.Null)
-
-        Assert.That (ex.InnerException, Is.InstanceOf<Exception>())
-        Assert.That (ex.InnerException.Message, Is.EqualTo "innerMsg")
-        Assert.That (ex.InnerException.StackTrace, Is.Null)
+        Assert.That (ex, Is.InstanceOf<MarshalledException>())
+        Assert.That(ex.FullDescription.Trim().Length, Is.GreaterThan 0)
+        Assert.That (
+            MarshallingData.Sanitize ex.FullDescription,
+            Is.EqualTo (MarshallingData.Sanitize "System.Exception: msg ---> System.Exception: innerMsg   --- End of inner exception stack trace ---")
+        )
 
     [<Test>]
     member __.``can serialize custom exceptions``() =
         let json = SerializeCustomException ()
         Assert.That(json, Is.Not.Null)
-        Assert.That(json, Is.Not.Empty)
-        Assert.That(MarshallingData.SerializedExceptionsAreSame json MarshallingData.CustomExceptionExampleInJson false msg)
+        Assert.That(json.Trim(), Is.Not.Empty)
+        Assert.That(MarshallingData.SerializedExceptionsAreSame json MarshallingData.CustomExceptionExampleInJson msg)
 
     [<Test>]
-    member __.``serializing custom exception not prepared for binary serialization, throws``() =
-        let exToSerialize = CustomExceptionWithoutSerializationCtor "msg"
-        let ex: MarshallingCompatibilityException =
-            Assert.Throws(fun _ -> Marshalling.Serialize exToSerialize |> ignore<string>)
-        Assert.That(ex, Is.TypeOf<MarshallingCompatibilityException>())
-        Assert.That(ex.Message, IsString.WhichContains "GWallet.Backend.Tests.CustomExceptionWithoutSerializationCtor")
+    member __.``serializing custom exception without inner ex ctor does not crash``() =
+        let exToSerialize = CustomExceptionWithoutInnerExceptionCtor "msg"
+        let serializedEx = (Marshalling.Serialize exToSerialize).Trim()
+        Assert.That(serializedEx, Is.Not.Null)
+        Assert.That(serializedEx.Trim().Length, Is.GreaterThan 0)
 
     [<Test>]
     member __.``can deserialize custom exceptions``() =
@@ -188,21 +184,24 @@ type ExceptionMarshalling () =
                 Assert.Inconclusive "Fix the serialization test first"
                 failwith "unreachable"
 
-        let ex: Exception = Marshalling.Deserialize customExceptionSerialized
+        let ex: MarshalledException = Marshalling.Deserialize customExceptionSerialized
         Assert.That(ex, Is.Not.Null)
-        Assert.That(ex, Is.InstanceOf<CustomException>())
-        Assert.That(ex.Message, Is.EqualTo "msg")
-        Assert.That(ex.InnerException, Is.Null)
-        Assert.That(ex.StackTrace, Is.Null)
+        Assert.That(ex, Is.InstanceOf<MarshalledException>())
+        Assert.That(
+            MarshallingData.Sanitize ex.FullDescription,
+            Is.EqualTo (MarshallingData.Sanitize "GWallet.Backend.Tests.CustomException: msg")
+        )
 
     [<Test>]
     member __.``can serialize F# custom exceptions``() =
         let json = SerializeCustomFSharpException ()
         Assert.That(json, Is.Not.Null)
-        Assert.That(json, Is.Not.Empty)
-
-        // strangely enough, message would be different between linux_vanilla_dotnet6 and other dotnet6 configs (e.g. Windows, macOS, Linux-github)
-        Assert.That(MarshallingData.SerializedExceptionsAreSame json MarshallingData.CustomFSharpExceptionExampleInJson true msg)
+        Assert.That(json.Trim(), Is.Not.Empty)
+#if !LEGACY_FRAMEWORK
+        Assert.That(MarshallingData.SerializedExceptionsAreSame json MarshallingData.CustomFSharpExceptionExampleInJson msg)
+#else
+        Assert.Ignore legacyIgnoreMsg
+#endif
 
     [<Test>]
     member __.``can deserialize F# custom exceptions``() =
@@ -214,36 +213,34 @@ type ExceptionMarshalling () =
                 Assert.Inconclusive "Fix the serialization test first"
                 failwith "unreachable"
 
-        let ex: Exception = Marshalling.Deserialize customExceptionSerialized
+        let ex: MarshalledException = Marshalling.Deserialize customExceptionSerialized
         Assert.That(ex, Is.Not.Null)
-        Assert.That(ex, Is.InstanceOf<CustomFSharpException>())
-        Assert.That(ex.Message, Is.Not.Null)
-        Assert.That(ex.Message, Is.Not.Empty)
-        Assert.That(ex.InnerException, Is.Null)
-        Assert.That(ex.StackTrace, Is.Null)
+        Assert.That(ex, Is.InstanceOf<MarshalledException>())
+        Assert.That(ex.FullDescription.Trim().Length, Is.GreaterThan 0)
+
+        if ex.FullDescription.Contains "of type" then
+            // old version of .NET6? (happens in stockdotnet6 CI lanes)
+            Assert.That(
+                MarshallingData.Sanitize ex.FullDescription,
+                Is.EqualTo (MarshallingData.Sanitize "GWallet.Backend.Tests.CustomFSharpException: Exception of type 'GWallet.Backend.Tests.CustomFSharpException' was thrown.")
+            )
+        else
+            Assert.That(
+                MarshallingData.Sanitize ex.FullDescription,
+                Is.EqualTo (MarshallingData.Sanitize "GWallet.Backend.Tests.CustomFSharpException: CustomFSharpException")
+            )
 
-    // TODO: test marshalling custom exceptions with custom properties/fields, and custom F# exception with subtypes
 
     [<Test>]
     member __.``can serialize full exceptions (all previous features combined)``() =
         let json = SerializeFullException ()
 
         Assert.That(json, Is.Not.Null)
-        Assert.That(json, Is.Not.Empty)
-
+        Assert.That(json.Trim(), Is.Not.Empty)
 #if !LEGACY_FRAMEWORK
-        Assert.That(MarshallingData.SerializedExceptionsAreSame json MarshallingData.FullExceptionExampleInJson false msg)
+        Assert.That(MarshallingData.SerializedExceptionsAreSame json MarshallingData.FullExceptionExampleInJson msg)
 #else
-        if Config.IsWindowsPlatform () then
-            let serializedExceptionsAreSame =
-                try
-                    MarshallingData.SerializedExceptionsAreSame json MarshallingData.FullExceptionExampleInJson false msg
-                with
-                | :? AssertionException ->
-                    MarshallingData.SerializedExceptionsAreSame json MarshallingData.FullExceptionWindowsLegacyExampleInJson false legacyMsg
-            Assert.That serializedExceptionsAreSame
-        else
-            Assert.That(MarshallingData.SerializedExceptionsAreSame json MarshallingData.FullExceptionUnixLegacyExampleInJson false legacyMsg)
+        Assert.Ignore legacyIgnoreMsg
 #endif
 
     [<Test>]
@@ -256,12 +253,23 @@ type ExceptionMarshalling () =
                 Assert.Inconclusive "Fix the serialization test first"
                 failwith "unreachable"
 
-        let ex: Exception = Marshalling.Deserialize fullExceptionSerialized
+        let ex: MarshalledException = Marshalling.Deserialize fullExceptionSerialized
         Assert.That(ex, Is.Not.Null)
-        Assert.That(ex, Is.InstanceOf<CustomException> ())
-        Assert.That(ex.Message, Is.Not.Null)
-        Assert.That(ex.Message, Is.Not.Empty)
-        Assert.That(ex.InnerException, Is.Not.Null)
-        Assert.That(ex.StackTrace, Is.Not.Null)
-        Assert.That(ex.StackTrace, Is.Not.Empty)
+        Assert.That(ex, Is.InstanceOf<MarshalledException> ())
+        Assert.That(ex.FullDescription.Trim().Length, Is.GreaterThan 0)
+
+#if !LEGACY_FRAMEWORK
+        Assert.That(
+            MarshallingData.Sanitize ex.FullDescription,
+            Is.EqualTo (
+                MarshallingData.Sanitize
+                <| sprintf
+                    "GWallet.Backend.Tests.CustomException: msg ---> GWallet.Backend.Tests.CustomException: innerMsg   --- End of inner exception stack trace ---   at GWallet.Backend.Tests.ExceptionMarshalling.SerializeFullException() in %s/ExceptionMarshalling.fs:line 61"
+                    MarshallingData.ThisProjPath
+            )
+        )
+#else
+        Assert.Ignore legacyIgnoreMsg
+#endif
+
 

src/GWallet.Backend.Tests/GWallet.Backend.Tests-legacy.fsproj

@@ -75,15 +75,10 @@
     <EmbeddedResource Include="data\unsignedAndFormattedEtherTransaction.json" />
     <EmbeddedResource Include="data\basicException.json" />
     <EmbeddedResource Include="data\realException.json" />
-    <EmbeddedResource Include="data\realException_unixLegacy.json" />
-    <EmbeddedResource Include="data\realException_windowsLegacy.json" />
     <EmbeddedResource Include="data\innerException.json" />
     <EmbeddedResource Include="data\customException.json" />
     <EmbeddedResource Include="data\customFSharpException.json" />
-    <EmbeddedResource Include="data\customFSharpException_legacy.json" />
     <EmbeddedResource Include="data\fullException.json" />
-    <EmbeddedResource Include="data\fullException_unixLegacy.json" />
-    <EmbeddedResource Include="data\fullException_windowsLegacy.json" />
     <Compile Include="ElectrumIntegrationTests.fs" />
     <Compile Include="WarpWallet.fs" />
     <Compile Include="CompoundBalanceCaching.fs" />

src/GWallet.Backend.Tests/GWallet.Backend.Tests.fsproj

@@ -39,18 +39,13 @@
   <ItemGroup>
     <EmbeddedResource Include="data\basicException.json" />
     <EmbeddedResource Include="data\customFSharpException.json" />
-    <EmbeddedResource Include="data\customFSharpException_legacy.json" />
     <EmbeddedResource Include="data\realException.json" />
-    <EmbeddedResource Include="data\realException_unixLegacy.json" />
-    <EmbeddedResource Include="data\realException_windowsLegacy.json" />
     <EmbeddedResource Include="data\signedAndFormattedEtherTransaction.json" />
     <EmbeddedResource Include="data\customException.json" />
     <EmbeddedResource Include="data\unsignedAndFormattedSaiTransaction.json" />
     <EmbeddedResource Include="data\unsignedAndFormattedBtcTransaction.json" />
     <EmbeddedResource Include="data\unsignedAndFormattedEtherTransaction.json" />
     <EmbeddedResource Include="data\fullException.json" />
-    <EmbeddedResource Include="data\fullException_unixLegacy.json" />
-    <EmbeddedResource Include="data\fullException_windowsLegacy.json" />
     <EmbeddedResource Include="data\signedAndFormattedBtcTransaction.json" />
     <EmbeddedResource Include="data\signedAndFormattedSaiTransaction.json" />
     <EmbeddedResource Include="data\innerException.json" />