feat(browse): Wave-0 Batch E — UntilStable settle loop + BrowserSessionService fallback

Task 9: DiscoverTreeAsync UntilStable settle loop (FOCAS) — re-capture on a 1s interval until the node set is non-empty and stable across two passes, bounded by open-timeout; on timeout with a prior non-empty capture, return it (best-effort) instead of failing. Task 11: BrowserSessionService resolves bespoke-first, falls back to IUniversalDriverBrowser when no bespoke browser matches and CanBrowse is true; new CanBrowse on the service. 16 unit tests green (4 settle + 12 service).
2026-07-15 17:31:50 -04:00
parent fa339a5565
commit 698703744f
7 changed files with 266 additions and 11 deletions
@@ -0,0 +1,87 @@
+using Microsoft.Extensions.Logging.Abstractions;
+using Shouldly;
+using ZB.MOM.WW.OtOpcUa.Commons.Browsing;
+using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
+using Xunit;
+
+namespace ZB.MOM.WW.OtOpcUa.Commons.Tests.Browsing;
+
+public class DiscoveryDriverBrowserSettleTests
+{
+    private static readonly TimeSpan ShortShutdown = TimeSpan.FromMilliseconds(200);
+
+    private static DiscoveryDriverBrowser Browser(IDriverFactory factory, TimeSpan openTimeout) =>
+        new(factory, NullLogger<DiscoveryDriverBrowser>.Instance, openTimeout, ShortShutdown);
+
+    private static void StreamN(IAddressSpaceBuilder builder, int n)
+    {
+        for (var i = 0; i < n; i++)
+            builder.Variable($"T{i}", $"T{i}",
+                new DriverAttributeInfo($"Dev.T{i}", DriverDataType.Float64, false, null,
+                    SecurityClassification.Operate, false));
+    }
+
+    [Fact]
+    public async Task UntilStable_RerunsUntilNonEmptyAndStable()
+    {
+        // Pass 1 streams nothing (FixedTree cache still filling); passes 2+ stream 3 nodes.
+        var driver = new FakeDiscoveryDriver
+        {
+            RediscoverPolicy = DiscoveryRediscoverPolicy.UntilStable,
+            OnDiscover = (b, idx) => { if (idx >= 2) StreamN(b, 3); return Task.CompletedTask; },
+        };
+        var browser = Browser(FakeDriverFactory.Of(() => driver), TimeSpan.FromSeconds(30));
+
+        var session = await browser.OpenAsync("Fake", "{}", CancellationToken.None);
+        var root = await session.RootAsync(CancellationToken.None);
+
+        root.Count.ShouldBe(3);
+        driver.DiscoverCalls.ShouldBeGreaterThanOrEqualTo(3); // empty -> 3 -> 3-stable
+    }
+
+    [Fact]
+    public async Task UntilStable_NeverStable_ReturnsLastNonEmptyAtTimeout()
+    {
+        // Node count grows every pass — never stabilises; on open-timeout return the last capture.
+        var driver = new FakeDiscoveryDriver
+        {
+            RediscoverPolicy = DiscoveryRediscoverPolicy.UntilStable,
+            OnDiscover = (b, idx) => { StreamN(b, idx); return Task.CompletedTask; },
+        };
+        var browser = Browser(FakeDriverFactory.Of(() => driver), TimeSpan.FromSeconds(3));
+
+        var session = await browser.OpenAsync("Fake", "{}", CancellationToken.None);
+        var root = await session.RootAsync(CancellationToken.None);
+
+        root.ShouldNotBeEmpty(); // last non-empty capture, not an exception
+    }
+
+    [Fact]
+    public async Task UntilStable_NeverAnyNodes_FailsAtOpenTimeout()
+    {
+        // Every pass empty — no non-empty capture to fall back to, so the timeout surfaces.
+        var driver = new FakeDiscoveryDriver
+        {
+            RediscoverPolicy = DiscoveryRediscoverPolicy.UntilStable,
+            OnDiscover = (_, _) => Task.CompletedTask,
+        };
+        var browser = Browser(FakeDriverFactory.Of(() => driver), TimeSpan.FromSeconds(2));
+
+        await Should.ThrowAsync<OperationCanceledException>(
+            () => browser.OpenAsync("Fake", "{}", CancellationToken.None));
+    }
+
+    [Fact]
+    public async Task OncePolicy_SingleDiscoverPass()
+    {
+        var driver = new FakeDiscoveryDriver
+        {
+            RediscoverPolicy = DiscoveryRediscoverPolicy.Once,
+            OnDiscover = (b, _) => { StreamN(b, 3); return Task.CompletedTask; },
+        };
+        var browser = Browser(FakeDriverFactory.Of(() => driver), TimeSpan.FromSeconds(30));
+
+        await browser.OpenAsync("Fake", "{}", CancellationToken.None);
+        driver.DiscoverCalls.ShouldBe(1);
+    }
+}