Merge pull request #16 from altso/exceptions

Log hosting exceptions to debug output

Author: altso

Source/ExcelRna.Extensions.Hosting.Tests/HostedExcelAddInTests.cs

@@ -1,3 +1,5 @@
+using System;
+using System.Collections.Generic;
 using System.Threading;
 using System.Threading.Tasks;
 using ExcelDna.Integration;
@@ -24,6 +26,19 @@ public void HostedExcelAddIn_should_start_and_stop_host()
         Assert.False(testExcelAddIn.IsRunning);
     }
 
+    [Fact]
+    public void HostedExcelAddIn_should_call_OnException()
+    {
+        // ARRANGE
+        var invalidExcelAddIn = new InvalidExcelAddIn();
+        IExcelAddIn addIn = invalidExcelAddIn;
+
+        // ACT & ASSERT
+        Assert.Throws<ApplicationException>(addIn.AutoOpen);
+        Assert.Throws<AggregateException>(addIn.AutoClose);
+        Assert.Equal(2, invalidExcelAddIn.Exceptions.Count);
+    }
+
     private class TestExcelAddIn : HostedExcelAddIn, IHostedService
     {
         public bool IsRunning { get; private set; }
@@ -43,4 +58,22 @@ public Task StopAsync(CancellationToken cancellationToken)
         protected override IHostBuilder CreateHostBuilder() => Host.CreateDefaultBuilder()
             .ConfigureServices(services => services.AddHostedService(_ => this));
     }
+
+    private class InvalidExcelAddIn : HostedExcelAddIn, IHostedService
+    {
+        public List<Exception> Exceptions { get; } = new();
+
+        public Task StartAsync(CancellationToken cancellationToken) => throw new ApplicationException();
+
+        public Task StopAsync(CancellationToken cancellationToken) => throw new ApplicationException();
+
+        protected override IHostBuilder CreateHostBuilder() => new HostBuilder()
+            .ConfigureServices(services => services.AddHostedService(_ => this));
+
+        protected override void OnException(Exception e)
+        {
+            base.OnException(e);
+            Exceptions.Add(e);
+        }
+    }
 }

Source/ExcelRna.Extensions.Hosting/HostedExcelAddIn.cs

@@ -1,4 +1,6 @@
-using ExcelDna.Integration;
+using System;
+using System.Diagnostics;
+using ExcelDna.Integration;
 using Microsoft.Extensions.Hosting;
 
 namespace ExcelRna.Extensions.Hosting;
@@ -15,19 +17,40 @@ protected virtual void AutoClose(IHost host)
     {
     }
 
+    protected virtual void OnException(Exception e)
+    {
+        Debug.WriteLine(e);
+    }
+
     protected abstract IHostBuilder CreateHostBuilder();
 
     void IExcelAddIn.AutoOpen()
     {
-        _host = CreateHostBuilder().Build();
-        _host.StartAsync().GetAwaiter().GetResult();
-        AutoOpen(_host);
+        try
+        {
+            _host = CreateHostBuilder().Build();
+            _host.StartAsync().GetAwaiter().GetResult();
+            AutoOpen(_host);
+        }
+        catch (Exception e)
+        {
+            OnException(e);
+            throw;
+        }
     }
 
     void IExcelAddIn.AutoClose()
     {
-        AutoClose(_host);
-        _host.StopAsync().GetAwaiter().GetResult();
-        _host.Dispose();
+        try
+        {
+            AutoClose(_host);
+            _host.StopAsync().GetAwaiter().GetResult();
+            _host.Dispose();
+        }
+        catch (Exception e)
+        {
+            OnException(e);
+            throw;
+        }
     }
 }