Remove exception from decoding issued currencies which evaluate to 'XRP' (#1920)

* Remove throw and revise tests

* Update chai dependency

* Disabling linter error about extraneous import

* Fix typo in test description

* Revert unnecessary test changes

* Remove unnecessary comments

* Revert chai change

* Add HISTORY.md

* Revert chai change in package-lock as well

* Fix typo

* Check the result of the decoding

* Update tests with correct expected behavior.

* Fix tests and update currency.js

* Update currency.ts

packages/ripple-binary-codec/HISTORY.md

@@ -5,6 +5,7 @@
 - Exported `TRANSACTION_TYPES` value
 ### Fixed
 - Adds missing fields from XLS-20 NFT implementation
+- Fixed error being raised when decoding issued currencies in non-standard formats that decode to XRP.
 
 ## 1.2.3 (2022-2-2)
 - Fix issue where ISO is invalid when parsing currency code

packages/ripple-binary-codec/src/types/currency.ts

@@ -29,9 +29,7 @@ function isIsoCode(iso: string): boolean {
 function isoCodeFromHex(code: Buffer): string | null {
   const iso = code.toString()
   if (iso === 'XRP') {
-    throw new Error(
-      'Disallowed currency code: to indicate the currency XRP you must use 20 bytes of 0s',
-    )
+    return null
   }
   if (isIsoCode(iso)) {
     return iso

packages/ripple-binary-codec/test/hash.test.js

@@ -50,10 +50,9 @@ describe('Hash256', function () {
 })
 
 describe('Currency', function () {
-  test('Will throw an error for dodgy XRP', function () {
-    expect(() =>
-      Currency.from('0000000000000000000000005852500000000000'),
-    ).toThrow()
+  test('Decoding allows dodgy XRP without throwing', function () {
+    const currencyCode = '0000000000000000000000005852500000000000'
+    expect(Currency.from(currencyCode).toJSON()).toBe(currencyCode)
   })
   test('Currency with lowercase letters decode to hex', () => {
     expect(Currency.from('xRp').toJSON()).toBe(

packages/ripple-binary-codec/test/tx-encode-decode.test.js

@@ -50,6 +50,28 @@ describe('encoding and decoding tx_json', function () {
     const decoded = decode(encoded)
     expect(my_tx).toEqual(decoded)
   })
+  test('can decode a transaction with an issued currency that evaluates to XRP', function () {
+    // Encoding is done prior, because this is disallowed during encoding with client libraries to avoid scam XRP tokens.
+    const expectedTx = {
+      TransactionType: 'TrustSet',
+      Flags: 0,
+      Sequence: 19,
+      LimitAmount: {
+        value: '200',
+        currency: '0000000000000000000000005852500000000000',
+        issuer: 'r9hEDb4xBGRfBCcX3E4FirDWQBAYtpxC8K',
+      },
+      Fee: '10',
+      SigningPubKey:
+        '023076CBB7A61837F1A23D4A3DD7CE810B694992EB0959AB9D6F4BB6FED6F8CC26',
+      TxnSignature:
+        '304502202D0CD77D8E765E3783C309CD663723B18406B7950A348A6F301492916A990FC70221008A76D586111205304F10ADEFDFDDAF804EF202D8CD1E492DC6E1AA8030EA1844',
+      Account: 'rPtfQWdcdhuL9eNeNv5YfmekSX3K7vJHbG',
+    }
+    const encoded = encode(expectedTx)
+    const decoded = decode(encoded)
+    expect(expectedTx).toEqual(decoded)
+  })
   test('throws when Amount is invalid', function () {
     const my_tx = Object.assign({}, tx_json, {
       Amount: '1000.001',