fix preparePay bug and add integration test for it

packages/taler-integrationtests/src/harness.ts

@@ -41,6 +41,9 @@ import {
   CoreApiResponse,
   PreparePayResult,
   PreparePayRequest,
+  codecForPreparePayResultPaymentPossible,
+  codecForPreparePayResult,
+  OperationFailedError,
 } from "taler-wallet-core";
 import { URL } from "url";
 import axios from "axios";
@@ -1111,7 +1114,7 @@ export class WalletCli {
 
   async apiRequest(
     request: string,
-    payload: Record<string, unknown>,
+    payload: unknown,
   ): Promise<CoreApiResponse> {
     const wdb = this.globalTestState.testDir + "/walletdb.json";
     const resp = await sh(
@@ -1144,6 +1147,10 @@ export class WalletCli {
   }
 
   async preparePay(req: PreparePayRequest): Promise<PreparePayResult> {
-    throw Error("not implemented");
+    const resp = await this.apiRequest("preparePay", req);
+    if (resp.type === "response") {
+      return codecForPreparePayResult().decode(resp.result);
+    }
+    throw new OperationFailedError(resp.error);
   }
 }

packages/taler-integrationtests/src/test-payment-idempotency.ts

@@ -0,0 +1,103 @@
+/*
+ This file is part of GNU Taler
+ (C) 2020 Taler Systems S.A.
+
+ GNU Taler is free software; you can redistribute it and/or modify it under the
+ terms of the GNU General Public License as published by the Free Software
+ Foundation; either version 3, or (at your option) any later version.
+
+ GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+ WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+ A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License along with
+ GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+ */
+
+/**
+ * Imports.
+ */
+import { runTest, GlobalTestState } from "./harness";
+import { createSimpleTestkudosEnvironment, withdrawViaBank } from "./helpers";
+import { PreparePayResultType } from "taler-wallet-core";
+
+/**
+ * Test the wallet-core payment API, especially that repeated operations
+ * return the expected result.
+ */
+runTest(async (t: GlobalTestState) => {
+  // Set up test environment
+
+  const {
+    wallet,
+    bank,
+    exchange,
+    merchant,
+  } = await createSimpleTestkudosEnvironment(t);
+
+  // Withdraw digital cash into the wallet.
+
+  await withdrawViaBank(t, { wallet, bank, exchange, amount: "TESTKUDOS:20" });
+
+  // Set up order.
+
+  const orderResp = await merchant.createOrder("default", {
+    order: {
+      summary: "Buy me!",
+      amount: "TESTKUDOS:5",
+      fulfillment_url: "taler://fulfillment-success/thx",
+    },
+  });
+
+  let orderStatus = await merchant.queryPrivateOrderStatus(
+    "default",
+    orderResp.order_id,
+  );
+
+  t.assertTrue(orderStatus.order_status === "unpaid");
+
+  const talerPayUri = orderStatus.taler_pay_uri;
+
+  // Make wallet pay for the order
+
+  const preparePayResult = await wallet.preparePay({
+    talerPayUri: orderStatus.taler_pay_uri,
+  });
+
+  const preparePayResultRep = await wallet.preparePay({
+    talerPayUri: orderStatus.taler_pay_uri,
+  });
+
+  t.assertTrue(
+    preparePayResult.status === PreparePayResultType.PaymentPossible,
+  );
+  t.assertTrue(
+    preparePayResultRep.status === PreparePayResultType.PaymentPossible,
+  );
+
+  const proposalId = preparePayResult.proposalId;
+
+  const r2 = await wallet.apiRequest("confirmPay", {
+    // FIXME: should be validated, don't cast!
+    proposalId: proposalId,
+  });
+  t.assertTrue(r2.type === "response");
+
+  // Check if payment was successful.
+
+  orderStatus = await merchant.queryPrivateOrderStatus(
+    "default",
+    orderResp.order_id,
+  );
+
+  t.assertTrue(orderStatus.order_status === "paid");
+
+  const preparePayResultAfter = await wallet.preparePay({
+    talerPayUri,
+  });
+
+  t.assertTrue(preparePayResultAfter.status === PreparePayResultType.AlreadyConfirmed);
+  t.assertTrue(preparePayResultAfter.paid === true);
+
+  await t.shutdown();
+});

packages/taler-integrationtests/src/test-payment.ts

@@ -19,6 +19,7 @@
  */
 import { runTest, GlobalTestState } from "./harness";
 import { createSimpleTestkudosEnvironment, withdrawViaBank } from "./helpers";
+import { PreparePayResultType } from "taler-wallet-core";
 
 /**
  * Run test for basic, bank-integrated withdrawal.
@@ -56,14 +57,15 @@ runTest(async (t: GlobalTestState) => {
 
   // Make wallet pay for the order
 
-  const r1 = await wallet.apiRequest("preparePay", {
+  const preparePayResult = await wallet.preparePay({
     talerPayUri: orderStatus.taler_pay_uri,
   });
-  t.assertTrue(r1.type === "response");
+
+  t.assertTrue(preparePayResult.status === PreparePayResultType.PaymentPossible);
 
   const r2 = await wallet.apiRequest("confirmPay", {
     // FIXME: should be validated, don't cast!
-    proposalId: (r1.result as any).proposalId,
+    proposalId: preparePayResult.proposalId,
   });
   t.assertTrue(r2.type === "response");
 

packages/taler-wallet-core/src/operations/pay.ts

@@ -980,17 +980,17 @@ export async function preparePayForUri(
       amountRaw: Amounts.stringify(purchase.contractData.amount),
       amountEffective: Amounts.stringify(purchase.payCostInfo.totalCost),
     };
-  } else if (purchase.paymentSubmitPending) {
+  } else {
+    const paid = !purchase.paymentSubmitPending;
     return {
       status: PreparePayResultType.AlreadyConfirmed,
       contractTerms: JSON.parse(purchase.contractTermsRaw),
-      paid: false,
+      paid,
       amountRaw: Amounts.stringify(purchase.contractData.amount),
       amountEffective: Amounts.stringify(purchase.payCostInfo.totalCost),
+      ...(paid ? { nextUrl: purchase.contractData.orderId } : {}),
     };
   }
-  // FIXME: we don't handle aborted payments correctly here.
-  throw Error("BUG: invariant violation (purchase status)");
 }
 
 /**

packages/taler-wallet-core/src/types/walletTypes.ts

@@ -48,6 +48,7 @@ import {
   codecForBoolean,
   codecForConstString,
   codecForAny,
+  buildCodecForUnion,
 } from "../util/codec";
 import { AmountString, codecForContractTerms } from "./talerTypes";
 import { TransactionError } from "./transactions";
@@ -399,6 +400,14 @@ export const codecForPreparePayResultAlreadyConfirmed = (): Codec<
     .property("contractTerms", codecForAny())
     .build("PreparePayResultAlreadyConfirmed");
 
+export const codecForPreparePayResult = (): Codec<PreparePayResult> => 
+  buildCodecForUnion<PreparePayResult>()
+      .discriminateOn("status")
+      .alternative(PreparePayResultType.AlreadyConfirmed, codecForPreparePayResultAlreadyConfirmed())
+      .alternative(PreparePayResultType.InsufficientBalance, codecForPreparePayResultInsufficientBalance())
+      .alternative(PreparePayResultType.PaymentPossible, codecForPreparePayResultPaymentPossible())
+      .build("PreparePayResult");
+
 export type PreparePayResult =
   | PreparePayResultInsufficientBalance
   | PreparePayResultAlreadyConfirmed