test(ablegacy): make the LastSuccessfulRead-advanced assertions deterministic by waiting for the clock to pass the init stamp (lmxopcua#767)

Claude-Session: https://claude.ai/code/session_01GT67AEHd2Acv1YPwGfXEoV

tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.Tests/NativePcccBridgeStatusHealthTests.cs

@@ -44,6 +44,19 @@ public sealed class NativePcccBridgeStatusHealthTests
         return server;
     }
 
+    /// <summary>
+    ///     InitializeAsync stamps <c>LastSuccessfulRead</c> with <c>DateTime.UtcNow</c> and the read stamps its own
+    ///     <c>UtcNow</c> microseconds later; on a coarse/identical clock reading the two are equal, so an "advanced"
+    ///     assertion (<c>ShouldNotBe(before)</c>) failed ~70% of runs (lmxopcua#767). Spin until the clock has strictly
+    ///     passed the init stamp so any later stamp is provably newer. The assertion itself is unchanged.
+    /// </summary>
+    private static void WaitUntilClockPast(DateTime? stamp)
+    {
+        if (stamp is null) return;
+        var spin = new SpinWait();
+        while (DateTime.UtcNow <= stamp.Value) spin.SpinOnce();
+    }
+
 #pragma warning disable OTOPCUA0001 // the driver is called directly to pin its OWN classification (no resilience wrap)
     private static async Task<AbLegacyDriver> DriverAsync(FakeEipServer server)
     {
@@ -86,6 +99,7 @@ public sealed class NativePcccBridgeStatusHealthTests
         await using var server = StsServer(0x60);
         var driver = await DriverAsync(server);
         var before = driver.GetHealth().LastSuccessfulRead;
+        WaitUntilClockPast(before);
 
         var result = (await driver.ReadAsync(["T"], ct)).Single();
 
@@ -116,6 +130,7 @@ public sealed class NativePcccBridgeStatusHealthTests
         await using var server = general == 0 ? StsServer(0x10) : CipEnvelopeServer(general);
         var driver = await DriverAsync(server);
         var before = driver.GetHealth().LastSuccessfulRead;
+        WaitUntilClockPast(before);
 
         var result = (await driver.ReadAsync(["T"], ct)).Single();