fix(wallet): Adding incrementNextAddress() method to wallet adapter

src/adapters/wallet.js

@@ -44,6 +44,9 @@ class WalletAdapter {
 
         walletData = walletInstance.walletInfo
 
+        // Add the nextAddress property
+        walletData.nextAddress = 1
+
         // Write the wallet data to the JSON file.
         await this.jsonFiles.writeJSON(walletData, this.WALLET_FILE)
       }
@@ -57,6 +60,26 @@ class WalletAdapter {
     }
   }
 
+  // Increments the 'nextAddress' property in the wallet file. This property
+  // indicates the HD index that should be used to generate a key pair for
+  // storing funds for Offers.
+  // This function opens the wallet file, increments the nextAddress property,
+  // then saves the change to the wallet file.
+  async incrementNextAddress () {
+    try {
+      const walletData = await this.openWallet()
+      // console.log('original walletdata: ', walletData)
+
+      walletData.nextAddress++
+
+      // console.log('walletData finish: ', walletData)
+      await this.jsonFiles.writeJSON(walletData, this.WALLET_FILE)
+    } catch (err) {
+      console.error('Error in incrementNextAddress()')
+      throw err
+    }
+  }
+
   // Create an instance of minimal-slp-wallet. Use data in the wallet.json file,
   // and pass the bch-js information to the minimal-slp-wallet library.
   async instanceWallet (walletData, bchjs) {

test/unit/adapters/wallet.adapter.unit.js

@@ -196,6 +196,15 @@ describe('#wallet', () => {
       }
     })
   })
+
+  describe('#incrementNextAddress', () => {
+    it('should increment the nextAddress property', async () => {
+      // Ensure we open the test file, not the production wallet file.
+      uut.WALLET_FILE = testWalletFile
+
+      await uut.incrementNextAddress()
+    })
+  })
 })
 
 const deleteFile = (filepath) => {