Implement SEP-8 helper to get approval server url (#210)

What This PR implements the final helper function to get the approval server's url from the stellar.toml file at the issuer's home domain. It also piggybacks a test enhancement for the getRegulatedAssetsInTx. Why Approval Provider relies on a valid approval server URL for initialization.
stellar · Feb 23, 2021 · 99eadf1 · 99eadf1
1 parent 935d572
commit 99eadf1
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -1,6 +1,8 @@
 ## In master
 
 - Added SEP-8 Approval Provider.
+- Added SEP-8 helper functions: `getRegulatedAssetsInTx()` and
+  `getApprovalServerUrl()`.
 
 ## [v0.3.0-rc.4](https://github.com/stellar/js-stellar-wallets/compare/v0.3.0-rc.3...v0.3.0-rc.4)
 

diff --git a/plans/sep8.md b/plans/sep8.md
@@ -34,8 +34,10 @@ The high-level flow is:
 ### Types
 
 ```ts
-// This function returns the first regulated asset found in the transaction, if any.
-type getRegulatedAssetInTx = (params: Transaction) => Promise<RegulatedAssetInfo>;
+// This function returns the regulated assets found in the transaction, if any.
+type getRegulatedAssetsInTx = (
+  params: Transaction,
+) => Promise<RegulatedAssetInfo[]>;
 
 // Get the approval server's URL by fetching the stellar.toml file at the home domain and look for the matched currency.
 type getApprovalServerUrl = (params: RegulatedAssetInfo) => Promise<string>;
@@ -101,20 +103,20 @@ interface PostActionUrlResponse {
 import {
   ApprovalProvider,
   ApprovalResponseType,
-  getRegulatedAssetInTx,
+  getRegulatedAssetsInTx,
   getApprovalServerUrl,
 } from "wallet-sdk";
 
 // Parse transaction to check if it involves regulated assets
-const regulatedAsset = getRegulatedAssetInTx(transaction);
-if (!regulatedAsset) {
+const regulatedAssets = getRegulatedAssetsInTx(transaction);
+if (!regulatedAssets.length) {
   // No approval needed so submit to the network
   submitPayment(transaction);
   return;
 }
 
 // TODO: check whether the user is already authorized to transact the asset.
-
+const regulatedAsset = regulatedAssets[0];
 if (!regulatedAsset.home_domain) {
   // Report an error saying a certain information is missing in order to transact the asset.
   return;

diff --git a/src/sep8/getApprovalServerUrl.test.ts b/src/sep8/getApprovalServerUrl.test.ts
@@ -0,0 +1,154 @@
+import axios from "axios";
+import sinon from "sinon";
+import { Config } from "stellar-sdk";
+import { getApprovalServerUrl } from "./getApprovalServerUrl";
+
+describe("getApprovalServerUrl", () => {
+  let axiosMock: sinon.SinonMock;
+
+  beforeEach(() => {
+    axiosMock = sinon.mock(axios);
+    Config.setDefault();
+  });
+
+  afterEach(() => {
+    axiosMock.verify();
+    axiosMock.restore();
+  });
+
+  test("Issuer's Home Domain missing", async () => {
+    try {
+      // @ts-ignore
+      const res = await getApprovalServerUrl({
+        asset_code: "USD",
+        asset_issuer:
+          "GDBMMVJKWGT2N6HZ2BGMFHKODASVFYIHL2VS3RUTB3B3QES2R6YFXGQW",
+      });
+      expect("This test failed").toBe(null);
+    } catch (e) {
+      expect(e.toString()).toMatch(`Error: Issuer's home domain is missing`);
+    }
+  });
+
+  test("stellar.toml CURRENCIES missing", async () => {
+    const homeDomain = "example.com";
+    axiosMock
+      .expects("get")
+      .withArgs(sinon.match(`https://${homeDomain}/.well-known/stellar.toml`))
+      .returns(
+        Promise.resolve({
+          data: "",
+        }),
+      );
+
+    try {
+      // @ts-ignore
+      const res = await getApprovalServerUrl({
+        asset_code: "USD",
+        asset_issuer:
+          "GDBMMVJKWGT2N6HZ2BGMFHKODASVFYIHL2VS3RUTB3B3QES2R6YFXGQW",
+        home_domain: homeDomain,
+      });
+      expect("This test failed").toBe(null);
+    } catch (e) {
+      expect(e.toString()).toMatch(
+        `Error: stellar.toml at ${homeDomain} does not contain CURRENCIES` +
+          ` field`,
+      );
+    }
+  });
+
+  test("stellar.toml approval_server missing", async () => {
+    const homeDomain = "example.com";
+    axiosMock
+      .expects("get")
+      .withArgs(sinon.match(`https://${homeDomain}/.well-known/stellar.toml`))
+      .returns(
+        Promise.resolve({
+          data: `
+[[CURRENCIES]]
+code = "USD"
+issuer = "GDBMMVJKWGT2N6HZ2BGMFHKODASVFYIHL2VS3RUTB3B3QES2R6YFXGQW"
+`,
+        }),
+      );
+
+    try {
+      // @ts-ignore
+      const res = await getApprovalServerUrl({
+        asset_code: "USD",
+        asset_issuer:
+          "GDBMMVJKWGT2N6HZ2BGMFHKODASVFYIHL2VS3RUTB3B3QES2R6YFXGQW",
+        home_domain: homeDomain,
+      });
+      expect("This test failed").toBe(null);
+    } catch (e) {
+      expect(e.toString()).toMatch(
+        `Error: stellar.toml at ${homeDomain} does not contain` +
+          ` approval_server information for this asset`,
+      );
+    }
+  });
+
+  test("stellar.toml asset not found", async () => {
+    const homeDomain = "example.com";
+    axiosMock
+      .expects("get")
+      .withArgs(sinon.match(`https://${homeDomain}/.well-known/stellar.toml`))
+      .returns(
+        Promise.resolve({
+          data: `
+[[CURRENCIES]]
+code = "USD"
+issuer = "GDBMMVJKWGT2N6HZ2BGMFHKODASVFYIHL2VS3RUTB3B3QES2R6YFXGQW"
+`,
+        }),
+      );
+
+    try {
+      // @ts-ignore
+      const res = await getApprovalServerUrl({
+        asset_code: "EUR",
+        asset_issuer:
+          "GDBMMVJKWGT2N6HZ2BGMFHKODASVFYIHL2VS3RUTB3B3QES2R6YFXGQW",
+        home_domain: homeDomain,
+      });
+      expect("This test failed").toBe(null);
+    } catch (e) {
+      expect(e.toString()).toMatch(
+        `Error: CURRENCY EUR:` +
+          `GDBMMVJKWGT2N6HZ2BGMFHKODASVFYIHL2VS3RUTB3B3QES2R6YFXGQW` +
+          ` not found on stellar.toml at ${homeDomain}`,
+      );
+    }
+  });
+
+  test("approval server URL is returned", async () => {
+    const homeDomain = "example.com";
+    axiosMock
+      .expects("get")
+      .withArgs(sinon.match(`https://${homeDomain}/.well-known/stellar.toml`))
+      .returns(
+        Promise.resolve({
+          data: `
+[[CURRENCIES]]
+code = "USD"
+issuer = "GDBMMVJKWGT2N6HZ2BGMFHKODASVFYIHL2VS3RUTB3B3QES2R6YFXGQW"
+approval_server = "https://example.com/approve"
+`,
+        }),
+      );
+
+    try {
+      const res = await getApprovalServerUrl({
+        asset_code: "USD",
+        asset_issuer:
+          "GDBMMVJKWGT2N6HZ2BGMFHKODASVFYIHL2VS3RUTB3B3QES2R6YFXGQW",
+        home_domain: homeDomain,
+      });
+      expect(res).toEqual("https://example.com/approve");
+    } catch (e) {
+      expect(e).toBe(null);
+    }
+  });
+});
diff --git a/src/sep8/getApprovalServerUrl.ts b/src/sep8/getApprovalServerUrl.ts
@@ -0,0 +1,38 @@
+import { StellarTomlResolver } from "stellar-sdk";
+import { RegulatedAssetInfo } from "../types/sep8";
+
+export async function getApprovalServerUrl(
+  param: RegulatedAssetInfo,
+  opts: StellarTomlResolver.StellarTomlResolveOptions = {},
+): Promise<string> {
+  if (!param.home_domain) {
+    throw new Error(`Issuer's home domain is missing`);
+  }
+
+  const tomlObject = await StellarTomlResolver.resolve(param.home_domain, opts);
+  if (!tomlObject.CURRENCIES) {
+    throw new Error(
+      `stellar.toml at ${param.home_domain} does not contain CURRENCIES field`,
+    );
+  }
+
+  for (const ast of tomlObject.CURRENCIES) {
+    if (ast.code === param.asset_code && ast.issuer === param.asset_issuer) {
+      if (!ast.approval_server) {
+        throw new Error(
+          `stellar.toml at ${
+            param.home_domain
+          } does not contain approval_server information for this asset`,
+        );
+      }
+
+      return ast.approval_server;
+    }
+  }
+
+  throw new Error(
+    `CURRENCY ${param.asset_code}:${
+      param.asset_issuer
+    } not found on stellar.toml at ${param.home_domain}`,
+  );
+}
diff --git a/src/sep8/getRegulatedAssetsinTx.test.ts b/src/sep8/getRegulatedAssetsinTx.test.ts
@@ -431,6 +431,37 @@ describe("getRegulatedAssetsInTx with no ops moving assets", () => {
     }
   });
 
+  test("Revoke Claimable Balance Sponsorship Op", async () => {
+    const account = new Account(
+      "GD6WU64OEP5C4LRBH6NK3MHYIA2ADN6K6II6EXPNVUR3ERBXT4AN4ACD",
+      "2319149195853854",
+    );
+
+    const tx = new TransactionBuilder(account, {
+      fee: BASE_FEE,
+      networkPassphrase: Networks.TESTNET,
+    })
+      .addOperation(
+        Operation.revokeClaimableBalanceSponsorship({
+          balanceId:
+            "00000000929b20b72e5890ab51c24f1cc46fa01c4f318d8d33367d24dd614cfd" +
+            "f5491072",
+        }),
+      )
+      .setTimeout(30)
+      .build();
+
+    try {
+      const res = await getRegulatedAssetsInTx(
+        tx,
+        "https://horizon-live.stellar.org:1337",
+      );
+      expect(res).toEqual([]);
+    } catch (e) {
+      expect(e).toBe(null);
+    }
+  });
+
   test("Revoke Signer Sponsorship Op returns an empty array", async () => {
     const account = new Account(
       "GD6WU64OEP5C4LRBH6NK3MHYIA2ADN6K6II6EXPNVUR3ERBXT4AN4ACD",