Fix merge errors

hash/hash.go

@@ -75,6 +75,19 @@ func Random() (Hash, error) {
 	return hash, nil
 }
 
+// Decode decodes the base58 encoded hash. It returns error
+// when a hash isn't base58,encoded or hash length is invalid.
+func Decode(h string) (Hash, error) {
+	hash, err := base58.Decode(h)
+	if err != nil {
+		return nil, fmt.Errorf("hash: %s", err)
+	}
+	if len(hash) != size {
+		return nil, fmt.Errorf("hash: invalid length string")
+	}
+	return Hash(hash), nil
+}
+
 // IsZero reports whethere h represents empty hash.
 func (h Hash) IsZero() bool {
 	return len(h) == 0
@@ -126,6 +139,10 @@ func (h *Hash) UnmarshalJSON(data []byte) error {
 		return err
 	}
 
+	if str == "" {
+		return nil
+	}
+
 	h1, err := base58.Decode(str)
 	if err != nil {
 		return err

hash/hash_test.go

@@ -51,6 +51,18 @@ func TestRandom(t *testing.T) {
 	require.NoError(t, quick.Check(f, nil))
 }
 
+func TestDecode(t *testing.T) {
+	hash, err := Decode("4uQeVj5tqViQh7yWWGStvkEG1Zmhx6uasJtWCJziofM")
+	assert.NoError(t, err)
+	assert.Equal(t, hash, one)
+
+	_, err = Decode("0")
+	assert.Equal(t, "hash: invalid base58 digit ('0')", err.Error())
+
+	_, err = Decode("1")
+	assert.Equal(t, "hash: invalid length string", err.Error())
+}
+
 func TestIsZero(t *testing.T) {
 	assert.True(t, Hash{}.IsZero())
 }