copilot setup steps (#9409)

Author: danmoseley

.github/copilot-instructions.md

@@ -1,12 +1,11 @@
 # Instructions for GitHub and VisualStudio Copilot
 ### https://github.blog/changelog/2025-01-21-custom-repository-instructions-are-now-available-for-copilot-on-github-com-public-preview/
 
-
 ## General
 
 * Make only high confidence suggestions when reviewing code changes.
 * Always use the latest version C#, currently C# 13 features.
-* Files must have CRLF line endings.
+* Never change global.json unless explicitly asked to.
 
 ## Formatting
 
@@ -23,11 +22,15 @@
 * Always use `is null` or `is not null` instead of `== null` or `!= null`.
 * Trust the C# null annotations and don't add null checks when the type system says a value cannot be null.
 
-
 ### Testing
 
 * We use xUnit SDK v3 with Microsoft.Testing.Platform (https://learn.microsoft.com/dotnet/core/testing/microsoft-testing-platform-intro)
 * Do not emit "Act", "Arrange" or "Assert" comments.
-* We do not use any mocking framework at the moment. Use NSubstitute, if necessary. Never use Moq.
-* Use "snake_case" for test method names but keep the original method under test intact.
-  For example: when adding a test for methond "MethondToTest" instead of "MethondToTest_ShouldReturnSummarisedIssues" use "MethondToTest_should_return_summarised_issues".
+* We do not use any mocking framework at the moment.
+* Copy existing style in nearby files for test method names and capitalization.
+
+## Running tests
+
+(1) Build from the root with `build.sh`.
+(2) If that produces errors, fix those errors and build again. Repeat until the build is successful.
+(3) To then run tests, use a command similar to this `dotnet test tests/Aspire.Seq.Tests/Aspire.Seq.Tests.csproj` (using the path to whatever projects are applicable to the change).

.github/workflows/copilot-setup-steps.yml

@@ -0,0 +1,21 @@
+name: "Copilot Setup Steps"
+
+# Allow testing of the setup steps from your repository's "Actions" tab.
+on: workflow_dispatch
+
+jobs:
+  # The job MUST be called `copilot-setup-steps` or it will not be picked up by Copilot.
+  copilot-setup-steps:
+    runs-on: ubuntu-latest
+
+    permissions:
+      contents: read
+
+    # You can define any steps you want, and they will run before the agent starts.
+    # If you do not check out your code, Copilot will do this for you.
+    steps:
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+
+        # Include PrepareForHelix to maximise what is downloaded here
+      - name: Build solution
+        run: ./build.sh /p:PrepareForHelix=true