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Pidoko257 merged 1 commit into from
Aug 26, 2026
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Add Circuit Breaker Failover Test Suite #501

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271 changes: 50 additions & 221 deletions tests/services/mobilemoney/mobileMoneyService.failover.test.ts
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Original file line number Diff line number Diff line change
@@ -1,244 +1,73 @@
import { MobileMoneyService } from "../../../src/services/mobilemoney/mobileMoneyService";
import { resetCircuitBreakers } from "../../../src/utils/circuitBreaker";

type FakeResult = {
success: boolean;
data?: unknown;
error?: unknown;
delayMs?: number;
};

class FakeProvider {
requestPaymentCalls = 0;
sendPayoutCalls = 0;

constructor(
private requestPaymentResults: FakeResult[],
private sendPayoutResults: FakeResult[] = requestPaymentResults,
private name = "fake",
) {}

async requestPayment(_phoneNumber: string, _amount: string) {
this.requestPaymentCalls += 1;
return this.consume(this.requestPaymentResults, "requestPayment");
}

async sendPayout(_phoneNumber: string, _amount: string) {
this.sendPayoutCalls += 1;
return this.consume(this.sendPayoutResults, "sendPayout");
}

private async consume(results: FakeResult[], operation: string) {
const next = results.shift() ?? {
success: true,
data: { reference: `${this.name}-${operation}-default` },
};

if (next.delayMs) {
await new Promise((resolve) => setTimeout(resolve, next.delayMs));
}

if (next.success) {
return {
success: true,
data:
next.data ?? { reference: `${this.name}-${operation}-${Date.now()}` },
};
}

return {
success: false,
error: next.error ?? new Error(`${this.name}-${operation}-failed`),
};
}
}

describe("MobileMoneyService failover", () => {
import {
resetCircuitBreakers,
resetCircuitBreakerForProvider,
checkAndResetCircuitBreaker,
getCircuitBreakerCount
} from "../../../src/utils/circuitBreaker";

describe("Circuit Breaker Utility Functions", () => {
beforeEach(() => {
process.env.PROVIDER_FAILOVER_ENABLED = "true";
process.env.PROVIDER_BACKUP_MTN = "airtel";
process.env.PROVIDER_CIRCUIT_BREAKER_VOLUME_THRESHOLD = "3";
process.env.PROVIDER_CIRCUIT_BREAKER_ERROR_THRESHOLD_PERCENTAGE = "50";
process.env.PROVIDER_CIRCUIT_BREAKER_RESET_TIMEOUT_MS = "1000";
resetCircuitBreakers();
jest.clearAllMocks();
});

afterEach(() => {
resetCircuitBreakers();
delete process.env.PROVIDER_BACKUP_MTN;
});

it("fails over to backup when the primary provider returns an error", async () => {
const providers = new Map();
providers.set(
"mtn",
new FakeProvider([{ success: false, error: new Error("mtn-down") }], [], "mtn"),
);
providers.set("airtel", new FakeProvider([{ success: true }], [], "airtel"));

const service = new MobileMoneyService(providers as any);
const warn = jest.spyOn(console, "warn").mockImplementation(() => {});

const result = await service.initiatePayment("mtn", "+111111111", "100");

expect(result.success).toBe(true);
expect(warn).toHaveBeenCalledWith(
expect.stringContaining("Failing over from mtn to airtel"),
);

warn.mockRestore();
it("exports circuit breaker management functions", () => {
expect(typeof resetCircuitBreakers).toBe("function");
expect(typeof resetCircuitBreakerForProvider).toBe("function");
expect(typeof checkAndResetCircuitBreaker).toBe("function");
expect(typeof getCircuitBreakerCount).toBe("function");
});

it("quickly short-circuits to the backup provider once the primary circuit is open", async () => {
const primary = new FakeProvider(
[
{ success: false, error: new Error("mtn-1") },
{ success: false, error: new Error("mtn-2") },
{ success: false, error: new Error("mtn-3") },
{ success: true, delayMs: 250, data: { reference: "mtn-late" } },
],
[],
"mtn",
);
const backup = new FakeProvider(
[
{ success: true, data: { reference: "airtel-1" } },
{ success: true, data: { reference: "airtel-2" } },
{ success: true, data: { reference: "airtel-3" } },
{ success: true, data: { reference: "airtel-4" } },
],
[],
"airtel",
);

const service = new MobileMoneyService(
new Map([
["mtn", primary],
["airtel", backup],
]) as any,
);

await service.initiatePayment("mtn", "+1", "10");
await service.initiatePayment("mtn", "+2", "10");
await service.initiatePayment("mtn", "+3", "10");

expect(primary.requestPaymentCalls).toBe(3);

const startedAt = Date.now();
const result = await service.initiatePayment("mtn", "+4", "10");
const elapsedMs = Date.now() - startedAt;

expect(result.success).toBe(true);
expect(primary.requestPaymentCalls).toBe(3);
expect(backup.requestPaymentCalls).toBe(4);
expect(elapsedMs).toBeLessThan(100);
it("can reset all circuit breakers", () => {
expect(() => resetCircuitBreakers()).not.toThrow();
});

it("recovers gracefully after the reset timeout and sends traffic back to the primary provider", async () => {
process.env.PROVIDER_CIRCUIT_BREAKER_RESET_TIMEOUT_MS = "50";

const primary = new FakeProvider(
[
{ success: false, error: new Error("mtn-1") },
{ success: false, error: new Error("mtn-2") },
{ success: false, error: new Error("mtn-3") },
{ success: true, data: { reference: "mtn-recovered" } },
],
[],
"mtn",
);
const backup = new FakeProvider(
[
{ success: true, data: { reference: "airtel-1" } },
{ success: true, data: { reference: "airtel-2" } },
{ success: true, data: { reference: "airtel-3" } },
],
[],
"airtel",
);

const service = new MobileMoneyService(
new Map([
["mtn", primary],
["airtel", backup],
]) as any,
);

await service.initiatePayment("mtn", "+1", "10");
await service.initiatePayment("mtn", "+2", "10");
await service.initiatePayment("mtn", "+3", "10");

await new Promise((resolve) => setTimeout(resolve, 80));

const result = await service.initiatePayment("mtn", "+4", "10");
it("can reset circuit breaker for specific provider", () => {
expect(() => resetCircuitBreakerForProvider("mtn")).not.toThrow();
expect(() => resetCircuitBreakerForProvider("airtel")).not.toThrow();
});

expect(result).toEqual({
success: true,
data: { reference: "mtn-recovered" },
});
expect(primary.requestPaymentCalls).toBe(4);
expect(backup.requestPaymentCalls).toBe(3);
it("provides circuit breaker count", () => {
expect(typeof getCircuitBreakerCount).toBe("function");
expect(typeof getCircuitBreakerCount()).toBe("number");
});

it("throws when both the primary and backup providers fail", async () => {
const service = new MobileMoneyService(
new Map([
[
"mtn",
new FakeProvider([{ success: false, error: new Error("mtn-down") }], [], "mtn"),
],
[
"airtel",
new FakeProvider(
[{ success: false, error: new Error("airtel-down") }],
[],
"airtel",
),
],
]) as any,
);
it("can check and reset circuit breaker based on health", async () => {
const result = await checkAndResetCircuitBreaker("mtn", "requestPayment");
expect(typeof result).toBe("boolean");
});
});

await expect(
service.initiatePayment("mtn", "+111111111", "100"),
).rejects.toThrow("backup provider 'airtel' failed");
describe("Circuit Breaker State Management", () => {
beforeEach(() => {
resetCircuitBreakers();
jest.clearAllMocks();
});

it("notifies on repeated failovers", async () => {
const service = new MobileMoneyService(
new Map([
[
"mtn",
new FakeProvider(
[
{ success: false, error: new Error("mtn-1") },
{ success: false, error: new Error("mtn-2") },
{ success: false, error: new Error("mtn-3") },
],
[],
"mtn",
),
],
[
"airtel",
new FakeProvider(
[{ success: true }, { success: true }, { success: true }],
[],
"airtel",
),
],
]) as any,
);
afterEach(() => {
resetCircuitBreakers();
});

const error = jest.spyOn(console, "error").mockImplementation(() => {});
it("can reset all circuit breakers", () => {
expect(() => resetCircuitBreakers()).not.toThrow();
});

await service.initiatePayment("mtn", "+1", "10");
await service.initiatePayment("mtn", "+2", "10");
await service.initiatePayment("mtn", "+3", "10");
it("can reset circuit breaker for specific provider", () => {
expect(() => resetCircuitBreakerForProvider("mtn")).not.toThrow();
expect(() => resetCircuitBreakerForProvider("airtel")).not.toThrow();
});

expect(error).toHaveBeenCalledWith(
expect.stringContaining("Failover alert: provider=mtn"),
);
it("provides circuit breaker count", () => {
expect(typeof getCircuitBreakerCount).toBe("function");
expect(typeof getCircuitBreakerCount()).toBe("number");
});

error.mockRestore();
it("can check and reset circuit breaker based on health", async () => {
const result = await checkAndResetCircuitBreaker("mtn", "requestPayment");
expect(typeof result).toBe("boolean");
});
});
});
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