feat: implement simulateContractCall in frontend/src/lib/stellar.ts (closes #127)

frontend/src/hooks/useMarketplace.ts

@@ -48,7 +48,7 @@ export function useMintTierBot() {
 export function useListings() {
   return useQuery({
     queryKey: ["listings"],
-    queryFn: getActiveListings,
+    queryFn: () => getActiveListings(),
     refetchInterval: 30000, // Poll every 30 seconds
     staleTime: 15000,
   });

frontend/src/lib/__tests__/stellar.test.ts

@@ -0,0 +1,133 @@
+/**
+ * Tests for connectFreighter and simulateContractCall in stellar.ts.
+ *
+ * Both @stellar/freighter-api and @stellar/stellar-sdk are fully mocked so the
+ * tests exercise only the wrapper logic (error normalization, simulation
+ * success/failure handling).
+ */
+
+// ── @stellar/stellar-sdk mock ───────────────────────────────────────────────
+const mockGetAccount = jest.fn();
+const mockSimulateTransaction = jest.fn();
+const mockIsSimulationError = jest.fn();
+const mockScValToNative = jest.fn();
+
+jest.mock("@stellar/stellar-sdk", () => ({
+  __esModule: true,
+  SorobanRpc: {
+    Server: jest.fn().mockImplementation(() => ({
+      getAccount: mockGetAccount,
+      simulateTransaction: mockSimulateTransaction,
+    })),
+    Api: {
+      isSimulationError: (...args: unknown[]) => mockIsSimulationError(...args),
+    },
+  },
+  Contract: jest.fn().mockImplementation(() => ({
+    call: jest.fn(() => ({ op: true })),
+  })),
+  TransactionBuilder: jest.fn().mockImplementation(() => ({
+    addOperation: jest.fn().mockReturnThis(),
+    setTimeout: jest.fn().mockReturnThis(),
+    build: jest.fn(() => ({ tx: true })),
+  })),
+  scValToNative: (...args: unknown[]) => mockScValToNative(...args),
+  nativeToScVal: jest.fn(() => ({ scv: true })),
+  xdr: {},
+}));
+
+// ── @stellar/freighter-api mock ─────────────────────────────────────────────
+jest.mock("@stellar/freighter-api", () => ({
+  __esModule: true,
+  isConnected: jest.fn(),
+  requestAccess: jest.fn(),
+  getNetwork: jest.fn(),
+}));
+
+import {
+  isConnected,
+  requestAccess,
+  getNetwork,
+} from "@stellar/freighter-api";
+import { connectFreighter, simulateContractCall } from "../stellar";
+
+const mockIsConnected = isConnected as jest.Mock;
+const mockRequestAccess = requestAccess as jest.Mock;
+const mockGetNetwork = getNetwork as jest.Mock;
+
+beforeEach(() => {
+  jest.clearAllMocks();
+});
+
+describe("connectFreighter", () => {
+  it("returns publicKey and network on success", async () => {
+    mockIsConnected.mockResolvedValue({ isConnected: true });
+    mockRequestAccess.mockResolvedValue({ address: "GABC123" });
+    mockGetNetwork.mockResolvedValue({
+      network: "TESTNET",
+      networkPassphrase: "Test SDF Network ; September 2015",
+    });
+
+    const result = await connectFreighter();
+    expect(result).toEqual({ publicKey: "GABC123", network: "TESTNET" });
+  });
+
+  it("throws when the extension is not installed", async () => {
+    mockIsConnected.mockResolvedValue({ isConnected: false });
+    await expect(connectFreighter()).rejects.toThrow(/not installed|not be detected/i);
+  });
+
+  it("throws a locked-wallet error when access returns a lock error", async () => {
+    mockIsConnected.mockResolvedValue({ isConnected: true });
+    mockRequestAccess.mockResolvedValue({
+      address: "",
+      error: { code: -1, message: "Wallet is locked" },
+    });
+    await expect(connectFreighter()).rejects.toThrow(/locked/i);
+  });
+
+  it("throws a rejection error when the user rejects the request", async () => {
+    mockIsConnected.mockResolvedValue({ isConnected: true });
+    mockRequestAccess.mockResolvedValue({
+      address: "",
+      error: { code: -2, message: "User rejected the request" },
+    });
+    await expect(connectFreighter()).rejects.toThrow(/rejected/i);
+  });
+});
+
+describe("simulateContractCall", () => {
+  beforeEach(() => {
+    mockGetAccount.mockResolvedValue({ accountId: () => "GSRC" });
+  });
+
+  it("returns the decoded native value on success", async () => {
+    mockSimulateTransaction.mockResolvedValue({
+      result: { retval: { xdr: true } },
+    });
+    mockIsSimulationError.mockReturnValue(false);
+    mockScValToNative.mockReturnValue(42);
+
+    const value = await simulateContractCall("CCONTRACT", "total_users", [], "GSRC");
+    expect(value).toBe(42);
+    expect(mockScValToNative).toHaveBeenCalledWith({ xdr: true });
+  });
+
+  it("throws when the simulation reports an error", async () => {
+    mockSimulateTransaction.mockResolvedValue({ error: "boom" });
+    mockIsSimulationError.mockReturnValue(true);
+
+    await expect(
+      simulateContractCall("CCONTRACT", "balance", [], "GSRC")
+    ).rejects.toThrow(/Simulation failed/i);
+  });
+
+  it("throws when there is no return value", async () => {
+    mockSimulateTransaction.mockResolvedValue({ result: {} });
+    mockIsSimulationError.mockReturnValue(false);
+
+    await expect(
+      simulateContractCall("CCONTRACT", "balance", [], "GSRC")
+    ).rejects.toThrow(/No return value/i);
+  });
+});