test(e2e): cap live browser contexts to bound Blazor circuit pressure (fixes full-suite timeouts); import negative-test review fixes

tests/ZB.MOM.WW.ScadaBridge.CentralUI.PlaywrightTests/PlaywrightFixture.cs

@@ -27,6 +27,23 @@ public class PlaywrightFixture : IAsyncLifetime
     public IPlaywright Playwright { get; private set; } = null!;
     public IBrowser Browser { get; private set; } = null!;
 
+    /// <summary>
+    /// Live browser contexts created by <see cref="NewPageAsync"/>, oldest first.
+    /// Capped to <see cref="MaxRetainedContexts"/> so finished tests' contexts are
+    /// closed eagerly rather than leaking for the whole run (see <see cref="NewPageAsync"/>).
+    /// </summary>
+    private readonly List<IBrowserContext> _contexts = new();
+
+    /// <summary>
+    /// Maximum number of browser contexts kept open at once. Each context holds a live
+    /// Blazor Server SignalR circuit on the Central UI; the full suite runs serially within
+    /// the <c>Playwright</c> collection, so contexts from already-finished tests can be closed
+    /// safely. Leaving every context open accumulated ~one circuit per test and slowed late
+    /// tests into navigation/visibility timeouts. A small cap (covering any single test that
+    /// opens more than one page) keeps server-side circuit pressure flat across the run.
+    /// </summary>
+    private const int MaxRetainedContexts = 4;
+
     public async Task InitializeAsync()
     {
         Playwright = await Microsoft.Playwright.Playwright.CreateAsync();
@@ -40,12 +57,36 @@ public class PlaywrightFixture : IAsyncLifetime
     }
 
     /// <summary>
-    /// Create a new browser context and page. Each test gets an isolated session.
+    /// Create a new browser context and page. Each test gets an isolated session. Contexts
+    /// from already-finished tests are closed eagerly once more than
+    /// <see cref="MaxRetainedContexts"/> are open, to bound the number of concurrent Blazor
+    /// Server circuits the run holds on the Central UI.
     /// </summary>
     public async Task<IPage> NewPageAsync()
     {
         var context = await Browser.NewContextAsync();
-        return await context.NewPageAsync();
+        var page = await context.NewPageAsync();
+
+        List<IBrowserContext> toClose = new();
+        lock (_contexts)
+        {
+            _contexts.Add(context);
+            int excess = _contexts.Count - MaxRetainedContexts;
+            if (excess > 0)
+            {
+                toClose = _contexts.GetRange(0, excess);
+                _contexts.RemoveRange(0, excess);
+            }
+        }
+
+        foreach (var old in toClose)
+        {
+            // Best-effort: a finished test's context may already be gone; never fail a test
+            // (or the next page creation) on teardown of a stale context.
+            try { await old.CloseAsync(); } catch { /* best-effort */ }
+        }
+
+        return page;
     }
 
     /// <summary>

tests/ZB.MOM.WW.ScadaBridge.CentralUI.PlaywrightTests/Transport/TransportImportTests.cs

@@ -190,7 +190,7 @@ public class TransportImportTests
             await CliRunner.AddAttributeAsync(tmplId, "Value", "Double");
             await CliRunner.BundleExportAsync(bundlePath, tmplId, "correct-passphrase-1", "src-env");
 
-            var page = await _fixture.NewAuthenticatedPageAsync("multi-role", "password");
+            var page = await _fixture.NewAuthenticatedPageAsync();
 
             // ── STEP 1: Upload ────────────────────────────────────────────────────────
             await page.GotoAsync($"{PlaywrightFixture.BaseUrl}/design/transport/import");
@@ -213,7 +213,9 @@ public class TransportImportTests
             await Assertions.Expect(page.Locator("[data-testid='error-message']"))
                 .ToContainTextAsync("Wrong passphrase. Please try again.", new() { Timeout = 10_000 });
             await Assertions.Expect(page.Locator("#import-passphrase")).ToBeVisibleAsync();
-            await Assertions.Expect(page.Locator("[data-testid='diff-summary']")).ToBeHiddenAsync();
+            // Assert the diff step is genuinely absent (the @switch never rendered it), not merely
+            // hidden — ToBeHiddenAsync is vacuously true for an element that doesn't exist.
+            await Assertions.Expect(page.Locator("[data-testid='diff-summary']")).ToHaveCountAsync(0);
 
             // Secondary indicator: one failed attempt recorded (1 of MaxUnlockAttempts).
             await Assertions.Expect(page.Locator("[data-testid='unlock-attempts']"))