feat(getKeyPair): Can generate key pairs

src/adapters/wallet.js

@@ -74,12 +74,52 @@ class WalletAdapter {
 
       // console.log('walletData finish: ', walletData)
       await this.jsonFiles.writeJSON(walletData, this.WALLET_FILE)
+
+      // Update the working instance of the wallet.
+      this.bchWallet.walletInfo.nextAddress++
+      // console.log('this.bchWallet.walletInfo: ', this.bchWallet.walletInfo)
+
+      return walletData.nextAddress
     } catch (err) {
       console.error('Error in incrementNextAddress()')
       throw err
     }
   }
 
+  // This method returns an object that contains a private key WIF, public address,
+  // and the index of the HD wallet that the key pair was generated from.
+  async getKeyPair () {
+    try {
+      const hdIndex = await this.incrementNextAddress()
+
+      const mnemonic = this.bchWallet.walletInfo.mnemonic
+
+      // root seed buffer
+      const rootSeed = await this.bchWallet.bchjs.Mnemonic.toSeed(mnemonic)
+
+      const masterHDNode = this.bchWallet.bchjs.HDNode.fromSeed(rootSeed)
+
+      // HDNode of BIP44 account
+      // const account = this.bchWallet.bchjs.HDNode.derivePath(masterHDNode, "m/44'/245'/0'")
+
+      const childNode = masterHDNode.derivePath(`m/44'/245'/0'/0/${hdIndex}`)
+
+      const cashAddress = this.bchWallet.bchjs.HDNode.toCashAddress(childNode)
+      const wif = this.bchWallet.bchjs.HDNode.toWIF(childNode)
+
+      const outObj = {
+        cashAddress,
+        wif,
+        hdIndex
+      }
+
+      return outObj
+    } catch (err) {
+      console.error('Error in getKeyPair()')
+      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

@@ -6,6 +6,7 @@
 const assert = require('chai').assert
 const sinon = require('sinon')
 const fs = require('fs')
+const BCHJS = require('@psf/bch-js')
 
 // Local libraries.
 const WalletAdapter = require('../../../src/adapters/wallet')
@@ -202,7 +203,57 @@ describe('#wallet', () => {
       // Ensure we open the test file, not the production wallet file.
       uut.WALLET_FILE = testWalletFile
 
-      await uut.incrementNextAddress()
+      // mock instance of minimal-slp-wallet
+      uut.bchWallet = new MockBchWallet()
+
+      const result = await uut.incrementNextAddress()
+
+      assert.equal(result, 2)
+    })
+
+    it('should catch and throw an error', async () => {
+      try {
+        // Force an error
+        sandbox.stub(uut, 'openWallet').rejects(new Error('test error'))
+
+        await uut.incrementNextAddress()
+
+        assert.fail('Unexpected code path')
+      } catch (err) {
+        assert.include(err.message, 'test error')
+      }
+    })
+  })
+
+  describe('#getKeyPair', () => {
+    it('should return an object with a key pair', async () => {
+      // Ensure we open the test file, not the production wallet file.
+      uut.WALLET_FILE = testWalletFile
+
+      // mock instance of minimal-slp-wallet
+      uut.bchWallet = new MockBchWallet()
+
+      const result = await uut.getKeyPair()
+      // console.log('result: ', result)
+
+      assert.property(result, 'cashAddress')
+      assert.property(result, 'wif')
+      assert.property(result, 'hdIndex')
+    })
+
+    it('should catch and throw an error', async () => {
+      try {
+        // Force an error
+        sandbox
+          .stub(uut, 'incrementNextAddress')
+          .rejects(new Error('test error'))
+
+        await uut.getKeyPair()
+
+        assert.fail('Unexpected code path')
+      } catch (err) {
+        assert.include(err.message, 'test error')
+      }
     })
   })
 })

test/unit/mocks/adapters/wallet.js

@@ -14,7 +14,8 @@ const mockWallet = {
   address: 'bitcoincash:qzl0d3gcqeypv4cy7gh8rgdszxa9vvm2acv7fqtd00',
   slpAddress: 'simpleledger:qzl0d3gcqeypv4cy7gh8rgdszxa9vvm2acq9zm7d33',
   legacyAddress: '1JQj1KcQL7GPKzc1D2PvdUSgw3MbDtrHzi',
-  hdPath: "m/44'/245'/0'/0/0"
+  hdPath: "m/44'/245'/0'/0/0",
+  nextAddress: 1
 }
 
 class MockBchWallet {