diff --git a/src/backend/fastlane.ts b/src/backend/fastlane.ts
index b05ea67..b993f4a 100644
--- a/src/backend/fastlane.ts
+++ b/src/backend/fastlane.ts
@@ -110,7 +110,9 @@ export class FastlaneBackend extends BaseBackend {
       const solverOpsWithScore = await response.json();
       return solverOpsWithScore.map((solverOpWithScore: any) =>
         OperationBuilder.newSolverOperation(
-          solverOpWithScore.solverOperation,
+          {
+            ...solverOpWithScore.solverOperation,
+          },
           solverOpWithScore.score,
         ),
       );
diff --git a/test/fastlane.test.ts b/test/fastlane.test.ts
new file mode 100644
index 0000000..fbc6ab2
--- /dev/null
+++ b/test/fastlane.test.ts
@@ -0,0 +1,254 @@
+import { FastlaneBackend } from "../src/backend/fastlane";
+import { OperationBuilder } from "../src/operation/builder";
+import {
+  UserOperation,
+  SolverOperation,
+  DAppOperation,
+  Bundle,
+} from "../src/operation";
+
+describe("FastlaneBackend", () => {
+  let backend: FastlaneBackend;
+  let fetchMock: jest.Mock;
+
+  beforeEach(() => {
+    backend = new FastlaneBackend({ basePath: "https://api.example.com" });
+    fetchMock = jest.fn();
+    (backend as any).fetch = fetchMock;
+  });
+
+  afterEach(() => {
+    jest.clearAllMocks();
+  });
+
+  const createValidUserOp = (): UserOperation => {
+    return OperationBuilder.newUserOperation({
+      from: "0x1234567890123456789012345678901234567890",
+      to: "0x2345678901234567890123456789012345678901",
+      value: BigInt(1),
+      gas: BigInt(1000000),
+      maxFeePerGas: BigInt(1000000000),
+      nonce: BigInt(1),
+      deadline: BigInt(1),
+      dapp: "0x3456789012345678901234567890123456789012",
+      control: "0x4567890123456789012345678901234567890123",
+      callConfig: BigInt(1),
+      sessionKey: "0x5678901234567890123456789012345678901234",
+      data: "0x",
+      signature: "0x",
+    });
+  };
+
+  const createValidDAppOp = (): DAppOperation => {
+    return OperationBuilder.newDAppOperation({
+      from: "0x1234567890123456789012345678901234567890",
+      to: "0x2345678901234567890123456789012345678901",
+      nonce: BigInt(1),
+      deadline: BigInt(1),
+      control: "0x3456789012345678901234567890123456789012",
+      bundler: "0x4567890123456789012345678901234567890123",
+      userOpHash:
+        "0x5678901234567890123456789012345678901234567890123456789012345678",
+      callChainHash:
+        "0x6789012345678901234567890123456789012345678901234567890123456789",
+      signature: "0x",
+    });
+  };
+
+  const createValidBundle = (): Bundle => {
+    return new Bundle(1, createValidUserOp(), [], createValidDAppOp());
+  };
+
+  describe("_submitUserOperation", () => {
+    it("should submit a user operation successfully", async () => {
+      const userOp = createValidUserOp();
+
+      const expectedHash = "0xabcdef1234567890";
+      fetchMock.mockResolvedValue({
+        ok: true,
+        json: async () => expectedHash,
+      });
+
+      const result = await backend._submitUserOperation(1, userOp, []);
+      expect(result).toBe(expectedHash);
+    });
+
+    it("should throw an error if submission fails", async () => {
+      const userOp = createValidUserOp();
+
+      fetchMock.mockResolvedValue({
+        ok: false,
+        json: async () => ({ message: "Submission failed" }),
+      });
+
+      await expect(backend._submitUserOperation(1, userOp, [])).rejects.toThrow(
+        "Submission failed",
+      );
+    });
+  });
+
+  describe("_getSolverOperations", () => {
+    it("should get solver operations successfully", async () => {
+      const expectedSolverOps = [
+        {
+          solverOperation: {
+            from: "0x1234567890123456789012345678901234567890",
+            to: "0x2345678901234567890123456789012345678901",
+            value: "0x1",
+            gas: "0xf4240",
+            maxFeePerGas: "0x3b9aca00",
+            deadline: "0x1",
+            solver: "0x3456789012345678901234567890123456789012",
+            control: "0x4567890123456789012345678901234567890123",
+            userOpHash:
+              "0x5678901234567890123456789012345678901234567890123456789012345678",
+            bidToken: "0x6789012345678901234567890123456789012345",
+            bidAmount: "0x1",
+            data: "0x",
+            signature: "0x",
+          },
+          score: 100,
+        },
+        {
+          solverOperation: {
+            from: "0x2345678901234567890123456789012345678901",
+            to: "0x3456789012345678901234567890123456789012",
+            value: "0x2",
+            gas: "0xf4240",
+            maxFeePerGas: "0x3b9aca00",
+            deadline: "0x1",
+            solver: "0x4567890123456789012345678901234567890123",
+            control: "0x5678901234567890123456789012345678901234",
+            userOpHash:
+              "0x6789012345678901234567890123456789012345678901234567890123456789",
+            bidToken: "0x7890123456789012345678901234567890123456",
+            bidAmount: "0x2",
+            data: "0x",
+            signature: "0x",
+          },
+          score: 90,
+        },
+      ];
+
+      fetchMock.mockResolvedValue({
+        ok: true,
+        json: async () => expectedSolverOps,
+      });
+
+      const userOp = createValidUserOp();
+      const result = await backend._getSolverOperations(1, userOp, "0x", true);
+      expect(result).toHaveLength(2);
+      expect(result[0]).toBeInstanceOf(SolverOperation);
+      expect(result[0].score).toBe(100);
+      expect(result[1]).toBeInstanceOf(SolverOperation);
+      expect(result[1].score).toBe(90);
+
+      expect(result[0].getField("from").value).toBe(
+        "0x1234567890123456789012345678901234567890",
+      );
+      expect(result[1].getField("from").value).toBe(
+        "0x2345678901234567890123456789012345678901",
+      );
+    });
+
+    it("should throw an error if getting solver operations fails", async () => {
+      fetchMock.mockResolvedValue({
+        ok: false,
+        json: async () => ({ message: "Failed to get solver operations" }),
+      });
+
+      const userOp = createValidUserOp();
+      await expect(
+        backend._getSolverOperations(1, userOp, "0x", true),
+      ).rejects.toThrow("Failed to get solver operations");
+    });
+  });
+
+  describe("_submitBundle", () => {
+    it("should submit a bundle successfully", async () => {
+      const mockBundle = createValidBundle();
+
+      const expectedMessage = "Bundle submitted successfully";
+      fetchMock.mockResolvedValue({
+        ok: true,
+        json: async () => expectedMessage,
+      });
+
+      const result = await backend._submitBundle(1, mockBundle);
+      expect(result).toBe(expectedMessage);
+    });
+
+    it("should throw an error if bundle submission fails", async () => {
+      const mockBundle = createValidBundle();
+
+      fetchMock.mockResolvedValue({
+        ok: false,
+        json: async () => ({ message: "Failed to submit bundle" }),
+      });
+
+      await expect(backend._submitBundle(1, mockBundle)).rejects.toThrow(
+        "Failed to submit bundle",
+      );
+    });
+  });
+
+  describe("_getBundleHash", () => {
+    it("should get bundle hash successfully", async () => {
+      const expectedHash = "0xabcdef1234567890";
+      fetchMock.mockResolvedValue({
+        ok: true,
+        json: async () => expectedHash,
+      });
+
+      const result = await backend._getBundleHash(1, "0x", true);
+      expect(result).toBe(expectedHash);
+    });
+
+    it("should throw an error if getting bundle hash fails", async () => {
+      fetchMock.mockResolvedValue({
+        ok: false,
+        json: async () => ({ message: "Failed to get bundle hash" }),
+      });
+
+      await expect(backend._getBundleHash(1, "0x", true)).rejects.toThrow(
+        "Failed to get bundle hash",
+      );
+    });
+  });
+
+  describe("_getBundleForUserOp", () => {
+    it("should get bundle for user operation successfully", async () => {
+      const mockBundleData = {
+        userOperation: createValidUserOp().toStruct(),
+        solverOperations: [],
+        dAppOperation: createValidDAppOp().toStruct(),
+      };
+
+      fetchMock.mockResolvedValue({
+        ok: true,
+        json: async () => mockBundleData,
+      });
+
+      const userOp = createValidUserOp();
+      const result = await backend._getBundleForUserOp(1, userOp, [], true);
+
+      expect(result).toBeInstanceOf(Bundle);
+      expect(result.userOperation).toBeInstanceOf(UserOperation);
+      expect(result.dAppOperation).toBeInstanceOf(DAppOperation);
+    });
+
+    it("should throw an error if getting bundle for user operation fails", async () => {
+      fetchMock.mockResolvedValue({
+        ok: false,
+        json: async () => ({
+          message: "Failed to get bundle for user operation",
+        }),
+      });
+
+      const userOp = createValidUserOp();
+      await expect(
+        backend._getBundleForUserOp(1, userOp, [], true),
+      ).rejects.toThrow("Failed to get bundle for user operation");
+    });
+  });
+});