From 3b948d68ea802cfc406b716cc0dd79ed2c4c0423 Mon Sep 17 00:00:00 2001
From: Sergey Kozyrenko <sirozha_blr@tut.by>
Date: Fri, 24 Jul 2026 13:00:06 +0700
Subject: [PATCH] test(e2e): prove the pager route by its history trail, not by
 sampling
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Sampling window.location on a timer measured the host's speed: on an unloaded
machine the sibling landed before the third sample, so the guard that the
samples spanned the switch failed 3 runs in 4. Weakening it to a length check
made it vacuous instead — the sampling loop always runs its full count.

Record every pushState/replaceState the app makes and assert the exact
sequence, which is what "without passing through the list" claims. Verified by
routing the pager through the list: the trail assert names the detour.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
---
 frontend/e2e/specs/flows/pager.spec.ts | 48 +++++++++++++-------------
 1 file changed, 24 insertions(+), 24 deletions(-)

diff --git a/frontend/e2e/specs/flows/pager.spec.ts b/frontend/e2e/specs/flows/pager.spec.ts
index 10e0a9d3..1ba32da8 100644
--- a/frontend/e2e/specs/flows/pager.spec.ts
+++ b/frontend/e2e/specs/flows/pager.spec.ts
@@ -32,43 +32,43 @@ test.describe('flow pager', { tag: ['@flows', '@smoke'] }, () => {
     test('steps to the sibling flow and back without passing through the list', async ({ page, pageErrorLog }) => {
         const header = page.locator('header');
 
+        await page.addInitScript(() => {
+            const trail: string[] = [];
+
+            (window as unknown as { __routeTrail: string[] }).__routeTrail = trail;
+
+            for (const method of ['pushState', 'replaceState'] as const) {
+                const original = history[method].bind(history);
+
+                history[method] = (state: unknown, unused: string, url?: null | string | URL) => {
+                    original(state, unused, url);
+                    trail.push(window.location.pathname);
+                };
+            }
+        });
+
         await page.goto('/flows/5');
         await expect(header.getByText('E2E Alpha')).toBeVisible();
 
-        await page.route('**/graphql', async (route) => {
-            await new Promise((resolve) => setTimeout(resolve, 300));
-            await route.fallback();
+        // Drop the router's own normalising replaceState from the initial load.
+        await page.evaluate(() => {
+            (window as unknown as { __routeTrail: string[] }).__routeTrail.length = 0;
         });
 
         await header.getByRole('button', { name: 'Next' }).click();
 
-        const samples = await page.evaluate(async () => {
-            const taken = [];
-
-            for (let index = 0; index < 10; index += 1) {
-                taken.push({
-                    hasPager: !!document.querySelector('header button[aria-label="Next"]'),
-                    isSiblingShown: document.querySelector('header')?.textContent?.includes('E2E Beta') ?? false,
-                    path: window.location.pathname,
-                });
-                await new Promise((resolve) => setTimeout(resolve, 30));
-            }
-
-            return taken;
-        });
-
         await expect(page).toHaveURL(/\/flows\/6$/);
         await expect(header.getByText('E2E Beta')).toBeVisible();
-
-        // Guards the delay above as much as the pager: without it the sibling lands inside the
-        // first sample and the loop measures nothing.
-        expect(samples.filter((sample) => !sample.isSiblingShown).length).toBeGreaterThan(2);
-        expect(samples.every((sample) => sample.hasPager)).toBe(true);
-        expect(samples.map((sample) => sample.path)).not.toContain('/flows');
+        await expect(header.getByRole('button', { name: 'Next' })).toBeVisible();
 
         await header.getByRole('button', { name: 'Previous' }).click();
 
         await expect(page).toHaveURL(/\/flows\/5$/);
+        await expect(header.getByText('E2E Alpha')).toBeVisible();
+
+        const trail = await page.evaluate(() => (window as unknown as { __routeTrail: string[] }).__routeTrail);
+
+        expect(trail, 'the pager must step straight between siblings').toEqual(['/flows/6', '/flows/5']);
         expectCleanPage(pageErrorLog);
     });
 });