Initial setup of repo with prompts and instructions

prompts/csharp-xunit.prompt.md

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+---
+mode: "agent"
+tools: ["codebase", "terminalCommand"]
+description: "Get best practices for XUnit unit testing, including data-driven tests"
+---
+
+# XUnit Best Practices
+
+Your goal is to help me write effective unit tests with XUnit, covering both standard and data-driven testing approaches.
+
+## Project Setup
+
+- Use a separate test project with naming convention `[ProjectName].Tests`
+- Reference Microsoft.NET.Test.Sdk, xunit, and xunit.runner.visualstudio packages
+- Create test classes that match the classes being tested (e.g., `CalculatorTests` for `Calculator`)
+- Use .NET SDK test commands: `dotnet test` for running tests
+
+## Test Structure
+
+- No test class attributes required (unlike MSTest/NUnit)
+- Use fact-based tests with `[Fact]` attribute for simple tests
+- Follow the Arrange-Act-Assert (AAA) pattern
+- Name tests using the pattern `MethodName_Scenario_ExpectedBehavior`
+- Use constructor for setup and `IDisposable.Dispose()` for teardown
+- Use `IClassFixture<T>` for shared context between tests in a class
+- Use `ICollectionFixture<T>` for shared context between multiple test classes
+
+## Standard Tests
+
+- Keep tests focused on a single behavior
+- Avoid testing multiple behaviors in one test method
+- Use clear assertions that express intent
+- Include only the assertions needed to verify the test case
+- Make tests independent and idempotent (can run in any order)
+- Avoid test interdependencies
+
+## Data-Driven Tests
+
+- Use `[Theory]` combined with data source attributes
+- Use `[InlineData]` for inline test data
+- Use `[MemberData]` for method-based test data
+- Use `[ClassData]` for class-based test data
+- Create custom data attributes by implementing `DataAttribute`
+- Use meaningful parameter names in data-driven tests
+
+## Assertions
+
+- Use `Assert.Equal` for value equality
+- Use `Assert.Same` for reference equality
+- Use `Assert.True`/`Assert.False` for boolean conditions
+- Use `Assert.Contains`/`Assert.DoesNotContain` for collections
+- Use `Assert.Matches`/`Assert.DoesNotMatch` for regex pattern matching
+- Use `Assert.Throws<T>` or `await Assert.ThrowsAsync<T>` to test exceptions
+- Use fluent assertions library for more readable assertions
+
+## Mocking and Isolation
+
+- Consider using Moq or NSubstitute alongside XUnit
+- Mock dependencies to isolate units under test
+- Use interfaces to facilitate mocking
+- Consider using a DI container for complex test setups
+
+## Test Organization
+
+- Group tests by feature or component
+- Use `[Trait("Category", "CategoryName")]` for categorization
+- Use collection fixtures to group tests with shared dependencies
+- Consider output helpers (`ITestOutputHelper`) for test diagnostics
+- Skip tests conditionally with `Skip = "reason"` in fact/theory attributes