wire: add unit test covering TxWitness JSON (un)marshal

wire/msgtx_test.go

@@ -6,6 +6,7 @@ package wire
 
 import (
 	"bytes"
+	"encoding/hex"
 	"fmt"
 	"io"
 	"reflect"
@@ -779,6 +780,56 @@ func TestTxWitnessSize(t *testing.T) {
 	}
 }
 
+// hexToBytes converts the passed hex string into bytes and will panic if there
+// is an error.  This is only provided for the hard-coded constants so errors in
+// the source code can be detected. It will only (and must only) be called with
+// hard-coded values.
+func hexToBytes(s string) []byte {
+	b, err := hex.DecodeString(s)
+	if err != nil {
+		panic("invalid hex in source file: " + s)
+	}
+	return b
+}
+
+// TestTxWitnessJSON performs tests to ensure that the TxWitness datatype can be
+// correctly marshalled to JSON and back.
+func TestTxWitnessJSON(t *testing.T) {
+	testCases := []struct {
+		// witness is the witness to encode and decode.
+		witness TxWitness
+	}{
+		{
+			witness: TxWitness{
+				hexToBytes(
+					"3045022100ee9fe8f9487afa9776647ebcf0883ce0cd37454d7ce198" +
+						"89d34ba2c99ce5a9f402200341cb469d0efd3955acb9e46f568d" +
+						"7e2cc10f9084aaff94ced6dc50a59134ad01",
+				),
+				hexToBytes(
+					"03f0000d0639a22bfaf217e4c94289c2b0cc7fa1036f7fd5d9f61a9d" +
+						"6ec153100e",
+				),
+			}},
+	}
+
+	t.Logf("Running %d tests", len(testCases))
+	for i, test := range testCases {
+		// Marshall to JSON.
+		jsonData, err := test.witness.MarshalJSON()
+		require.NoError(t, err)
+
+		// Unmarshall from JSON.
+		var unmarshalledWitness TxWitness
+		err = unmarshalledWitness.UnmarshalJSON(jsonData)
+		require.NoError(t, err)
+
+		// Ensure that the witness data is the same before and after the JSON
+		// marshalling/unmarshalling process.
+		require.Equal(t, test.witness, unmarshalledWitness, "Test %d", i)
+	}
+}
+
 // TestTxOutPointFromString performs tests to ensure that the outpoint string
 // parser works as expected.
 func TestTxOutPointFromString(t *testing.T) {