txnbuild: Adds helper function to craft assets from canonical strings. (

#3105) Introduces `func ParseAssetString(string) txnbuild.Asset` Co-authored-by: Leigh McCulloch <[email protected]>
stellar · Oct 9, 2020 · dd35fa3 · dd35fa3
1 parent b0ec1a1
commit dd35fa3
Show file tree

Hide file tree

Showing 3 changed files with 79 additions and 0 deletions.
diff --git a/txnbuild/CHANGELOG.md b/txnbuild/CHANGELOG.md
@@ -3,6 +3,9 @@
 All notable changes to this project will be documented in this
 file.  This project adheres to [Semantic Versioning](http://semver.org/).
 
+## Unreleased
+* Add helper function `ParseAssetString()`, making it easier to build an `Asset` structure from a string in [canonical form](https://github.com/stellar/stellar-protocol/blob/master/ecosystem/sep-0011.md#asset) and check its various properties ([#3105](https://github.com/stellar/go/pull/3105)).
+
 ## [v4.0.1](https://github.com/stellar/go/releases/tag/horizonclient-v4.0.1) - 2020-10-02
 
 * Fixed bug in `TransactionFromXDR()` which occurs when parsing transaction XDR envelopes which contain Protocol 14 operations.

diff --git a/txnbuild/helpers.go b/txnbuild/helpers.go
@@ -192,3 +192,24 @@ func NewValidationError(field, message string) *ValidationError {
 		Message: message,
 	}
 }
+
+// Parses an asset string in canonical form (SEP-11) into an Asset structure.
+// https://github.com/stellar/stellar-protocol/blob/master/ecosystem/sep-0011.md#asset
+func ParseAssetString(canonical string) (Asset, error) {
+	assets, err := xdr.BuildAssets(canonical)
+	if err != nil {
+		return nil, errors.Wrap(err, "error parsing asset string")
+	}
+
+	if len(assets) != 1 {
+		return nil, errors.New("error parsing out a single asset")
+	}
+
+	// The above returned a list, so we'll need to grab the first element.
+	asset, err := assetFromXDR(assets[0])
+	if err != nil {
+		return nil, errors.Wrap(err, "error parsing asset string via XDR types")
+	}
+
+	return asset, nil
+}
diff --git a/txnbuild/helpers_test.go b/txnbuild/helpers_test.go
@@ -1,6 +1,7 @@
 package txnbuild
 
 import (
+	"fmt"
 	"testing"
 
 	"github.com/stellar/go/keypair"
@@ -352,3 +353,57 @@ func TestValidateOfferManageSellOffer(t *testing.T) {
 	expectedErrMsg := "Field: OfferID, Error: amount can not be negative"
 	require.EqualError(t, err, expectedErrMsg, "valid offerID is required")
 }
+
+func TestAssetStringParsing(t *testing.T) {
+	kp0 := newKeypair0()
+	cred4 := CreditAsset{Code: "ABCD", Issuer: kp0.Address()}
+	xdr, err := cred4.ToXDR()
+	assert.NoError(t, err)
+	cred4String := xdr.StringCanonical()
+
+	kp1 := newKeypair1()
+	cred12 := CreditAsset{Code: "ABCD1234EFGH", Issuer: kp1.Address()}
+	xdr, err = cred12.ToXDR()
+	assert.NoError(t, err)
+	cred12String := xdr.StringCanonical()
+
+	native := NativeAsset{}
+	xdr, err = native.ToXDR()
+	assert.NoError(t, err)
+	nativeString := xdr.StringCanonical()
+
+	assets := make([]Asset, 3)
+	for i, input := range []string{nativeString, cred4String, cred12String} {
+		actual, innerErr := ParseAssetString(input)
+		assert.NoError(t, innerErr)
+		assets[i] = actual
+	}
+
+	compareAssets := func(expected Asset, actual Asset) bool {
+		expXdr, innerErr := expected.ToXDR()
+		if innerErr != nil {
+			return false
+		}
+
+		actXdr, innerErr := actual.ToXDR()
+		if innerErr != nil {
+			return false
+		}
+
+		return expXdr.Equals(actXdr)
+	}
+
+	assert.True(t, compareAssets(native, assets[0]))
+	assert.True(t, compareAssets(cred4, assets[1]))
+	assert.True(t, compareAssets(cred12, assets[2]))
+
+	// Now sanity-check some basic error cases
+
+	result, err := ParseAssetString("erroneous:maximus")
+	assert.Error(t, err)
+	assert.Equal(t, nil, result)
+
+	result, err = ParseAssetString(fmt.Sprintf("ABCD:%s,EFGH:%s", kp0.Address(), kp1.Address()))
+	assert.Error(t, err)
+	assert.Equal(t, nil, result)
+}