refactor: define DepositPreauth transaction model (#1545)

- Defines a TypeScript type for DepositPreauth
- Provides an optional function to users for verifying a DepositPreauth instance at runtime: verifyDepositPreauth()
- Adds tests for verifyDepositPreauth()

src/models/transactions/depositPreauth.ts

@@ -0,0 +1,46 @@
+import { ValidationError } from '../../common/errors'
+import { BaseTransaction, verifyBaseTransaction } from './common'
+
+export interface DepositPreauth extends BaseTransaction {
+    TransactionType: 'DepositPreauth'
+    Authorize?: string
+    Unauthorize?: string
+}
+
+/**
+ * 
+ * @param {DepositPreauth} tx A DepositPreauth Transaction.
+ * @returns {void}
+ * @throws {ValidationError} When the DepositPreauth is malformed.
+ */
+export function verifyDepositPreauth(tx: DepositPreauth): void {
+    verifyBaseTransaction(tx)
+
+    if (tx.Authorize !== undefined && tx.Unauthorize !== undefined) {
+        throw new ValidationError("DepositPreauth: can't provide both Authorize and Unauthorize fields")
+    }
+
+    if (tx.Authorize === undefined && tx.Unauthorize === undefined) {
+        throw new ValidationError('DepositPreauth: must provide either Authorize or Unauthorize field')
+    }
+
+    if (tx.Authorize !== undefined) {
+        if (typeof tx.Authorize !== 'string') {
+            throw new ValidationError('DepositPreauth: Authorize must be a string')
+        }
+
+        if (tx.Account === tx.Authorize) {
+            throw new ValidationError("DepositPreauth: Account can't preauthorize its own address")
+        }
+    }
+
+    if (tx.Unauthorize !== undefined) {
+        if (typeof tx.Unauthorize !== 'string') {
+            throw new ValidationError("DepositPreauth: Unauthorize must be a string")
+        }
+
+        if (tx.Account === tx.Unauthorize) {
+            throw new ValidationError("DepositPreauth: Account can't unauthorize its own address")
+        }
+    }
+}

src/models/transactions/index.ts

@@ -7,4 +7,5 @@ export * from './checkCash'
 export * from './checkCancel'
 export * from './accountDelete'
 export * from './signerListSet'
+export * from './depositPreauth'
 export * from './paymentTransaction'

src/models/transactions/transaction.ts

@@ -4,6 +4,7 @@ import { AccountSet } from "./accountSet"
 import { CheckCancel } from "./checkCancel"
 import { CheckCash } from "./checkCash"
 import { CheckCreate } from "./checkCreate"
+import { DepositPreauth } from "./depositPreauth"
 import { OfferCancel } from "./offerCancel"
 import { OfferCreate } from "./offerCreate"
 import { PaymentTransaction } from "./paymentTransaction"
@@ -15,7 +16,7 @@ export type Transaction =
      | CheckCancel
      | CheckCash
      | CheckCreate
-//   | DepositPreauth
+     | DepositPreauth
 //   | EscrowCancel
 //   | EscrowCreate
 //   | EscrowFinish

test/models/depositPreauth.ts

@@ -0,0 +1,83 @@
+import { ValidationError } from 'xrpl-local/common/errors'
+import { verifyDepositPreauth } from './../../src/models/transactions/depositPreauth'
+import { assert } from 'chai'
+
+/**
+ * DepositPreauth Transaction Verification Testing
+ *
+ * Providing runtime verification testing for each specific transaction type
+ */
+describe('DepositPreauth Transaction Verification', () => {
+    let depositPreauth
+
+    beforeEach(() => {
+        depositPreauth = {
+            TransactionType: 'DepositPreauth',
+            Account: 'rUn84CUYbNjRoTQ6mSW7BVJPSVJNLb1QLo',
+        } as any
+    })
+
+    it ('verifies valid DepositPreauth when only Authorize is provided', () => {
+        depositPreauth.Authorize = 'rsA2LpzuawewSBQXkiju3YQTMzW13pAAdW'
+        assert.doesNotThrow(() => verifyDepositPreauth(depositPreauth))
+    })
+
+    it ('verifies valid DepositPreauth when only Unauthorize is provided', () => {
+        depositPreauth.Unauthorize = 'raKEEVSGnKSD9Zyvxu4z6Pqpm4ABH8FS6n'
+        assert.doesNotThrow(() => verifyDepositPreauth(depositPreauth))
+    })
+
+    it ('throws when both Authorize and Unauthorize are provided', () => {
+        depositPreauth.Authorize = 'rsA2LpzuawewSBQXkiju3YQTMzW13pAAdW'
+        depositPreauth.Unauthorize = 'raKEEVSGnKSD9Zyvxu4z6Pqpm4ABH8FS6n'
+        assert.throws(
+            () => verifyDepositPreauth(depositPreauth),
+            ValidationError,
+            "DepositPreauth: can't provide both Authorize and Unauthorize fields"
+        )
+    })
+
+    it ('throws when neither Authorize nor Unauthorize are provided', () => {
+        assert.throws(
+            () => verifyDepositPreauth(depositPreauth),
+            ValidationError,
+            'DepositPreauth: must provide either Authorize or Unauthorize field'
+        )
+    })
+
+    it ('throws when Authorize is not a string', () => {
+        depositPreauth.Authorize = 1234
+        assert.throws(
+            () => verifyDepositPreauth(depositPreauth),
+            ValidationError,
+            'DepositPreauth: Authorize must be a string'
+        )
+    })
+
+    it ('throws when an Account attempts to preauthorize its own address', () => {
+        depositPreauth.Authorize = depositPreauth.Account
+        assert.throws(
+            () => verifyDepositPreauth(depositPreauth),
+            ValidationError,
+            "DepositPreauth: Account can't preauthorize its own address"
+        )
+    })
+
+    it ('throws when Unauthorize is not a string', () => {
+        depositPreauth.Unauthorize = 1234
+        assert.throws(
+            () => verifyDepositPreauth(depositPreauth),
+            ValidationError,
+            'DepositPreauth: Unauthorize must be a string'
+        )
+    })
+
+    it ('throws when an Account attempts to unauthorize its own address', () => {
+        depositPreauth.Unauthorize = depositPreauth.Account
+        assert.throws(
+            () => verifyDepositPreauth(depositPreauth),
+            ValidationError,
+            "DepositPreauth: Account can't unauthorize its own address"
+        )
+    })
+})