feat: expose ERC20 token originalAmount field

Author: mvines

module.flow.js

@@ -114,6 +114,7 @@ declare module '@solana/web3.js' {
     owner: PublicKey;
     amount: TokenAmount;
     source: null | PublicKey;
+    originalAmount: TokenAmount;
   |}
   declare type TokenAndPublicKey = [Token, PublicKey];
 

src/token-program.js

@@ -111,6 +111,12 @@ type TokenAccountInfo = {|
    * an allowance of tokens that may be transferred from the source account
    */
   source: null | PublicKey,
+
+  /**
+   * Original amount of tokens this delegate account was authorized to spend
+   * If `source` is null, originalAmount is zero
+   */
+  originalAmount: TokenAmount,
 |};
 
 /**
@@ -122,6 +128,7 @@ const TokenAccountInfoLayout = BufferLayout.struct([
   Layout.uint64('amount'),
   BufferLayout.u8('sourceOption'),
   Layout.publicKey('source'),
+  Layout.uint64('originalAmount'),
 ]);
 
 
@@ -320,7 +327,13 @@ export class Token {
     tokenAccountInfo.token = new PublicKey(tokenAccountInfo.token);
     tokenAccountInfo.owner = new PublicKey(tokenAccountInfo.owner);
     tokenAccountInfo.amount = TokenAmount.fromBuffer(tokenAccountInfo.amount);
-    tokenAccountInfo.source = tokenAccountInfo.sourceOption === 0 ? null : new PublicKey(tokenAccountInfo.source);
+    if (tokenAccountInfo.sourceOption === 0) {
+      tokenAccountInfo.source = null;
+      tokenAccountInfo.originalAmount = new TokenAmount();
+    } else {
+      tokenAccountInfo.source = new PublicKey(tokenAccountInfo.source);
+      tokenAccountInfo.originalAmount = TokenAmount.fromBuffer(tokenAccountInfo.originalAmount);
+    }
 
     if (!tokenAccountInfo.token.equals(this.token)) {
       throw new Error(

test/token-program.test.js

@@ -174,6 +174,7 @@ test('create new token', async () => {
   expect(accountInfo.owner.equals(initialOwner.publicKey)).toBe(true);
   expect(accountInfo.amount.toNumber()).toBe(10000);
   expect(accountInfo.source).toBe(null);
+  expect(accountInfo.originalAmount.toNumber()).toBe(0);
 });
 
 
@@ -379,6 +380,7 @@ test('approve/revoke', async () => {
             200, 1, 0, 0, 0, 0, 0, 0,
             1,
             ...initialOwnerTokenAccount.toBuffer(),
+            200, 1, 0, 0, 0, 0, 0, 0,
           ],
           executable: false,
           loader_program_id: [
@@ -393,6 +395,7 @@ test('approve/revoke', async () => {
   let delegateAccountInfo = await testToken.accountInfo(delegate);
 
   expect(delegateAccountInfo.amount.toNumber()).toBe(456);
+  expect(delegateAccountInfo.originalAmount.toNumber()).toBe(456);
   if (delegateAccountInfo.source === null) {
     throw new Error('source should not be null');
   } else {
@@ -432,6 +435,7 @@ test('approve/revoke', async () => {
             0, 0, 0, 0, 0, 0, 0, 0,
             1,
             ...initialOwnerTokenAccount.toBuffer(),
+            0, 0, 0, 0, 0, 0, 0, 0,
           ],
           executable: false,
           loader_program_id: [
@@ -444,8 +448,8 @@ test('approve/revoke', async () => {
   }
 
   delegateAccountInfo = await testToken.accountInfo(delegate);
-
   expect(delegateAccountInfo.amount.toNumber()).toBe(0);
+  expect(delegateAccountInfo.originalAmount.toNumber()).toBe(0);
   if (delegateAccountInfo.source === null) {
     throw new Error('source should not be null');
   } else {
@@ -517,20 +521,32 @@ test.skip('fail on approve overspend', async () => {
     2
   );
 
+  let delegateAccountInfo = await testToken.accountInfo(account1Delegate);
+  expect(delegateAccountInfo.amount.toNumber()).toBe(2);
+  expect(delegateAccountInfo.originalAmount.toNumber()).toBe(2);
+
   await testToken.transfer(
     owner,
     account1Delegate,
     account2,
     1,
   );
 
+  delegateAccountInfo = await testToken.accountInfo(account1Delegate);
+  expect(delegateAccountInfo.amount.toNumber()).toBe(1);
+  expect(delegateAccountInfo.originalAmount.toNumber()).toBe(2);
+
   await testToken.transfer(
     owner,
     account1Delegate,
     account2,
     1,
   );
 
+  delegateAccountInfo = await testToken.accountInfo(account1Delegate);
+  expect(delegateAccountInfo.amount.toNumber()).toBe(0);
+  expect(delegateAccountInfo.originalAmount.toNumber()).toBe(2);
+
   expect(
     testToken.transfer(
       owner,