feat(historian-gateway): GetHealthSnapshot via Probe/GetConnectionStatus (counter discipline)

Claude-Session: https://claude.ai/code/session_012SDSQ3AcaXqPcBtDESBRii
2026-06-26 16:45:40 -04:00
parent 1e93b2ebfb
commit 0a540d9f09
2 changed files with 131 additions and 5 deletions
@@ -0,0 +1,79 @@
+using Microsoft.Extensions.Logging.Abstractions;
+using Xunit;
+using ZB.MOM.WW.HistorianGateway.Contracts.Grpc;
+
+namespace ZB.MOM.WW.OtOpcUa.Driver.Historian.Gateway.Tests;
+
+public sealed class GatewayHealthSnapshotTests
+{
+    [Fact]
+    public async Task Counters_track_success_and_failure()
+    {
+        var fake = new FakeHistorianGatewayClient { RawSamples = Array.Empty<HistorianSample>() };
+        var ds = new GatewayHistorianDataSource(fake, NullLogger<GatewayHistorianDataSource>.Instance);
+        await ds.ReadRawAsync("T", default, default, 1, TestContext.Current.CancellationToken);
+        fake.ThrowOnRead = new InvalidOperationException("boom");
+        await Assert.ThrowsAnyAsync<Exception>(() => ds.ReadRawAsync("T", default, default, 1, TestContext.Current.CancellationToken));
+        var h = ds.GetHealthSnapshot();
+        Assert.Equal(2, h.TotalQueries);
+        Assert.Equal(1, h.TotalSuccesses);
+        Assert.Equal(1, h.TotalFailures);
+        Assert.Equal(1, h.ConsecutiveFailures);
+        Assert.Equal(h.TotalQueries, h.TotalSuccesses + h.TotalFailures); // invariant
+    }
+
+    [Fact]
+    public async Task Connection_state_reflects_GetConnectionStatus_flags()
+    {
+        var fake = new FakeHistorianGatewayClient
+        {
+            ConnectionStatus = new ConnectionStatus { ConnectedToServer = true, ConnectionKind = 0b11 }, // Process|Event
+        };
+        var ds = new GatewayHistorianDataSource(fake, NullLogger<GatewayHistorianDataSource>.Instance);
+        await ds.RefreshConnectionStateAsync(TestContext.Current.CancellationToken); // internal probe used by health hosted-service
+        var h = ds.GetHealthSnapshot();
+        Assert.True(h.ProcessConnectionOpen);
+        Assert.True(h.EventConnectionOpen);
+    }
+
+    [Fact]
+    public async Task GetHealthSnapshot_does_no_io_and_starts_with_connections_closed()
+    {
+        var fake = new FakeHistorianGatewayClient();
+        var ds = new GatewayHistorianDataSource(fake, NullLogger<GatewayHistorianDataSource>.Instance);
+        var h = ds.GetHealthSnapshot();
+        Assert.Equal(0, fake.GetConnectionStatusCallCount); // pure observation — never queries the gateway
+        Assert.False(h.ProcessConnectionOpen);
+        Assert.False(h.EventConnectionOpen);
+        await ValueTask.CompletedTask;
+    }
+
+    [Fact]
+    public async Task Disconnected_status_leaves_both_flags_closed()
+    {
+        var fake = new FakeHistorianGatewayClient
+        {
+            ConnectionStatus = new ConnectionStatus { ConnectedToServer = false, ConnectionKind = 0b11 },
+        };
+        var ds = new GatewayHistorianDataSource(fake, NullLogger<GatewayHistorianDataSource>.Instance);
+        await ds.RefreshConnectionStateAsync(TestContext.Current.CancellationToken);
+        var h = ds.GetHealthSnapshot();
+        Assert.False(h.ProcessConnectionOpen);
+        Assert.False(h.EventConnectionOpen);
+    }
+
+    [Fact]
+    public async Task Failed_status_query_degrades_flags_without_throwing()
+    {
+        var fake = new FakeHistorianGatewayClient
+        {
+            ConnectionStatus = new ConnectionStatus { ConnectedToServer = true, ConnectionKind = 0b11 },
+            GetConnectionStatusThrows = new InvalidOperationException("gateway unreachable"),
+        };
+        var ds = new GatewayHistorianDataSource(fake, NullLogger<GatewayHistorianDataSource>.Instance);
+        await ds.RefreshConnectionStateAsync(TestContext.Current.CancellationToken); // must not throw
+        var h = ds.GetHealthSnapshot();
+        Assert.False(h.ProcessConnectionOpen);
+        Assert.False(h.EventConnectionOpen);
+    }
+}