Merge pull request #90 from prom-client-net/feat/on-push-error

add error handling method

Author: phnx47

src/MetricPusherHostedService.cs

@@ -36,10 +36,14 @@ async Task DoPushAsync()
             {
                 await pusher.PushAsync();
             }
-            catch (Exception)
+            catch (Exception ex)
             {
-                // TODO: report error to DiagnosticSource?
+                OnPushError(pusher, ex);
             }
         }
     }
+
+    protected virtual void OnPushError(IMetricPusher metricPusher, Exception exception)
+    {
+    }
 }

tests/MetricPusherHostedServiceTests.cs

@@ -37,6 +37,21 @@ public async Task WithGivenInterval_PushMetricPeriodically(int seconds)
         await metricPusherMock.Received(3).PushAsync();
     }
 
+    [Fact]
+    public async Task OnPushError_HandlesException()
+    {
+        var pusher = Substitute.For<IMetricPusher>();
+        pusher.PushAsync().Returns(Task.FromException(new Exception("Simulated Push Exception")));
+        var ct = Arg.Any<CancellationToken>();
+
+        var hostedService = new TestableMetricPusherHostedService(pusher);
+        await hostedService.StartAsync(ct);
+        await Task.Delay(1000, ct);
+        await hostedService.StopAsync(ct);
+
+        Assert.True(hostedService.ErrorHandled);
+    }
+
     private static TimeSpan GetDelay(int seconds)
     {
         var milliseconds = seconds * 1000 + 100;

tests/TestableMetricPusherHostedService.cs

@@ -0,0 +1,11 @@
+namespace Prometheus.Client.MetricPusher.HostedService.Tests;
+
+public class TestableMetricPusherHostedService(IMetricPusher pusher) : MetricPusherHostedService(pusher)
+{
+    public bool ErrorHandled { get; private set; }
+
+    protected override void OnPushError(IMetricPusher metricPusher, Exception exception)
+    {
+        ErrorHandled = true;
+    }
+}