From dbaff1df3f0b2a64e1f77f69eb6938c68be915f9 Mon Sep 17 00:00:00 2001
From: Dan Espinosa <30415120+danespinosa@users.noreply.github.com>
Date: Tue, 21 Nov 2023 23:41:31 -0800
Subject: [PATCH] validate that providers are > 0 to provide clear error when
 using Diagnostics Client (#4411)
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validate that providers are > 0 otherwise START Failed 0x80131384 get…s
thrown and it's not clear what the issue is.

The current behavior when an empty list of providers is provided is to
throw START Failed 0x80131384 (BadEncoding) and that doesn't make it
very clear about what the issue is. This PR proposes validating the
number of providers so developers know that they should be providing 1
provider at least.

Before:
<img width="677" alt="image"
src="https://github.com/dotnet/diagnostics/assets/30415120/0dfe0963-97ae-4f1a-8ce5-46b992b55428">

After:
<img width="679" alt="image"
src="https://github.com/dotnet/diagnostics/assets/30415120/f171687b-eaa5-4bbb-945c-16a43f4b97b0">

Co-authored-by: Daniel Espinosa <luespino@microsoft.com>
---
 .../DiagnosticsClient/EventPipeSessionConfiguration.cs     | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/Microsoft.Diagnostics.NETCore.Client/DiagnosticsClient/EventPipeSessionConfiguration.cs b/src/Microsoft.Diagnostics.NETCore.Client/DiagnosticsClient/EventPipeSessionConfiguration.cs
index d4884b650..8f3f3b2b7 100644
--- a/src/Microsoft.Diagnostics.NETCore.Client/DiagnosticsClient/EventPipeSessionConfiguration.cs
+++ b/src/Microsoft.Diagnostics.NETCore.Client/DiagnosticsClient/EventPipeSessionConfiguration.cs
@@ -53,11 +53,16 @@ namespace Microsoft.Diagnostics.NETCore.Client
                 throw new ArgumentNullException(nameof(providers));
             };
 
+            _providers = new List<EventPipeProvider>(providers);
+            if (_providers.Count == 0)
+            {
+                throw new ArgumentException("At least one provider must be specified.");
+            };
+
             CircularBufferSizeInMB = circularBufferSizeMB;
             Format = format;
             RequestRundown = requestRundown;
             RequestStackwalk = requestStackwalk;
-            _providers = new List<EventPipeProvider>(providers);
         }
 
         /// <summary>
-- 
2.34.1