accounts/keystore: add test case for prefix bug fix

accounts/keystore/keystore_plain_test.go

@@ -17,6 +17,8 @@
 package keystore
 
 import (
+	"bytes"
+	"crypto/ecdsa"
 	"crypto/rand"
 	"encoding/hex"
 	"fmt"
@@ -253,6 +255,40 @@ func TestKeyForDirectICAP(t *testing.T) {
 	}
 }
 
+func TestNewKeyForDirectICAP(t *testing.T) {
+	randBytes := make([]byte, 64)
+	_, err := rand.Read(randBytes)
+	if err != nil {
+		panic("key generation: could not read from random source: " + err.Error())
+	}
+	reader := bytes.NewReader(randBytes)
+	privateKeyECDSA, err := ecdsa.GenerateKey(crypto.S256(), reader)
+	if err != nil {
+		panic("key generation: ecdsa.GenerateKey failed: " + err.Error())
+	}
+	key := newKeyFromECDSA(privateKeyECDSA)
+
+	tests := []struct {
+		setFirstByte  byte
+		isRecursion   bool
+		expectedError string
+	}{
+		{1, true, "failed to enter recursion: should recursively call NewKeyForDirectICAP until address meets Direct ICAP spec"},
+		{0, false, "address starts with 0 but in recursion mode"},
+	}
+	for _, tt := range tests {
+		key.Address[0] = tt.setFirstByte
+		isRecursion := false
+
+		if key.Address[0] != 0 { // xdc prefix can also be used for this comparison
+			isRecursion = true
+		}
+		if key.Address[0] == tt.setFirstByte && isRecursion != tt.isRecursion {
+			t.Errorf("%s", tt.expectedError)
+		}
+	}
+}
+
 func TestV3_31_Byte_Key(t *testing.T) {
 	t.Skip("This test does not ")
 	t.Parallel()