Fix ABI encoding of outcome; should be in a tuple

nitro/outcome.nim

@@ -6,7 +6,7 @@ export types
 export abi
 
 type
-  Outcome* = seq[AssetOutcome]
+  Outcome* = distinct seq[AssetOutcome]
   AssetOutcomeType* = enum
     allocationType = 0
     guaranteeType = 1
@@ -56,5 +56,10 @@ proc write*(writer: var AbiWriter, assetOutcome: AssetOutcome) =
   writer.write(content.finish())
   writer.finishTuple()
 
+proc write*(writer: var AbiWriter, outcome: Outcome) =
+  writer.startTuple()
+  writer.write(seq[AssetOutcome](outcome))
+  writer.finishTuple()
+
 proc hashOutcome*(outcome: Outcome): array[32, byte] =
   keccak256.digest(Abi.encode(outcome)).data

tests/nitro/examples.nim

@@ -62,6 +62,9 @@ proc example*(_: type AssetOutcome): AssetOutcome =
       guarantee: Guarantee.example
     )
 
+proc example*(_: type Outcome): Outcome =
+  Outcome(seq[AssetOutcome].example)
+
 proc example*(_: type State): State =
   State(
     turnNum: UInt48.example,

tests/nitro/testOutcome.nim

@@ -59,6 +59,14 @@ suite "outcome":
     writer.finishTuple()
     check Abi.encode(assetOutcome) == writer.finish()
 
+  test "encodes outcomes":
+    let outcome = Outcome.example()
+    var writer: AbiWriter
+    writer.startTuple()
+    writer.write(seq[AssetOutcome](outcome))
+    writer.finishTuple()
+    check Abi.encode(outcome) == writer.finish()
+
   test "hashes outcomes":
     let outcome = Outcome.example
     let encoded = Abi.encode(outcome)