From bafa9f827a479c340f6f57bd1a1ca679bc77e5ed Mon Sep 17 00:00:00 2001
From: Jason Salaber <jcsalaber@hotmail.com>
Date: Mon, 2 Dec 2024 11:31:46 -0500
Subject: [PATCH] fix: added test for non 100 or 0 start percentages

---
 .../bucketing/__tests__/bucketing.test.ts     | 75 +++++++++++++++++++
 lib/shared/bucketing/src/bucketing.ts         |  2 +-
 2 files changed, 76 insertions(+), 1 deletion(-)

diff --git a/lib/shared/bucketing/__tests__/bucketing.test.ts b/lib/shared/bucketing/__tests__/bucketing.test.ts
index b155c1b89..1b757d1fb 100644
--- a/lib/shared/bucketing/__tests__/bucketing.test.ts
+++ b/lib/shared/bucketing/__tests__/bucketing.test.ts
@@ -1416,6 +1416,81 @@ describe('Rollout Logic', () => {
             ).toBeFalsy()
         })
 
+        it('should handle stepped rollout with 0% start and 100% later stage', () => {
+            const rollout: PublicRollout = {
+                type: 'stepped',
+                startDate: new Date(),
+                startPercentage: 0,
+                stages: [
+                    {
+                        type: 'discrete',
+                        date: new Date(
+                            new Date().getTime() + 1000 * 60 * 60 * 24 * 7,
+                        ),
+                        percentage: 1,
+                    },
+                ],
+            }
+
+            // Before next stage - should be 0%
+            jest.useFakeTimers().setSystemTime(new Date())
+            for (let i = 0; i < 100; i++) {
+                expect(
+                    doesUserPassRollout({ rollout, boundedHash: i / 100 }),
+                ).toBeFalsy()
+            }
+
+            // After 100% stage - should pass all users
+            jest.useFakeTimers().setSystemTime(
+                new Date(new Date().getTime() + 1000 * 60 * 60 * 24 * 8),
+            )
+            for (let i = 0; i < 100; i++) {
+                expect(
+                    doesUserPassRollout({ rollout, boundedHash: i / 100 }),
+                ).toBeTruthy()
+            }
+
+            jest.useRealTimers()
+        })
+
+        it('should handle stepped rollout with 50% start and 100% later stage', () => {
+            const rollout: PublicRollout = {
+                type: 'stepped',
+                startDate: new Date(),
+                startPercentage: 0.5,
+                stages: [
+                    {
+                        type: 'discrete',
+                        date: new Date(
+                            new Date().getTime() + 1000 * 60 * 60 * 24 * 7,
+                        ),
+                        percentage: 1,
+                    },
+                ],
+            }
+
+            // Before next stage - should be 50%
+            jest.useFakeTimers().setSystemTime(new Date())
+            expect(
+                doesUserPassRollout({ rollout, boundedHash: 0.49 }),
+            ).toBeTruthy()
+            expect(
+                doesUserPassRollout({ rollout, boundedHash: 0.51 }),
+            ).toBeFalsy()
+
+            // After 100% stage - should pass all users
+            jest.useFakeTimers().setSystemTime(
+                new Date(new Date().getTime() + 1000 * 60 * 60 * 24 * 8),
+            )
+            for (let i = 0; i < 100; i++) {
+                expect(
+                    doesUserPassRollout({ rollout, boundedHash: i / 100 }),
+                ).toBeTruthy()
+            }
+
+            jest.useRealTimers()
+        })
+
         it('should handle stepped rollout with 100% start and 0% later stage', () => {
             const rollout: PublicRollout = {
                 type: 'stepped',
diff --git a/lib/shared/bucketing/src/bucketing.ts b/lib/shared/bucketing/src/bucketing.ts
index abf6dce06..03eda02ab 100644
--- a/lib/shared/bucketing/src/bucketing.ts
+++ b/lib/shared/bucketing/src/bucketing.ts
@@ -105,7 +105,7 @@ export const getCurrentRolloutPercentage = (
             : null)
 
     if (!currentStage) {
-        return 0
+        return start
     }
 
     if (!nextStage || nextStage.type === 'discrete') {