Add some retry behavior

1 files changed, 45 insertions, 0 deletions

diff --git a/tst/either.test.ts b/tst/either.test.ts
new file mode 100644
index 0000000..790d392
--- /dev/null
+++ b/tst/either.test.ts
@@ -0,0 +1,45 @@
+import { Either } from '@emprespresso/pengueno';
+
+describe('Either.retrying', () => {
+    beforeEach(() => {
+        jest.clearAllMocks();
+    });
+
+    test('succeeds on first attempt', async () => {
+        const supplier = jest.fn().mockResolvedValue(Either.right<string, string>('success'));
+        const interval = jest.fn().mockResolvedValue(undefined);
+
+        const result = await Either.retrying(supplier, 3, interval);
+
+        expect(result.right().get()).toBe('success');
+        expect(supplier).toHaveBeenCalledTimes(1);
+    });
+
+    test('never succeeds after all attempts', async () => {
+        const supplier = jest.fn().mockResolvedValue(Either.left<string, string>('failed'));
+        const interval = jest.fn().mockResolvedValue(undefined);
+
+        const result = await Either.retrying(supplier, 3, interval);
+
+        expect(result.left().get()).toBe('failed');
+        expect(supplier).toHaveBeenCalledTimes(3);
+    });
+
+    test('attempts correct number of times and calls interval with backoff', async () => {
+        const supplier = jest.fn()
+            .mockResolvedValueOnce(Either.left<string, string>('attempt 1 failed'))
+            .mockResolvedValueOnce(Either.left<string, string>('attempt 2 failed'))
+            .mockResolvedValueOnce(Either.right<string, string>('attempt 3 success'));
+
+        const interval = jest.fn().mockResolvedValue(undefined);
+
+        const result = await Either.retrying(supplier, 3, interval);
+
+        expect(result.right().get()).toBe('attempt 3 success');
+        expect(supplier).toHaveBeenCalledTimes(3);
+        expect(interval).toHaveBeenCalledTimes(3);
+        expect(interval).toHaveBeenNthCalledWith(1, 0);
+        expect(interval).toHaveBeenNthCalledWith(2, 1);
+        expect(interval).toHaveBeenNthCalledWith(3, 2);
+    });
+});