chore: solution review & modernization — AI config, CI coverage, test coverage

.github/copilot-instructions.md

@@ -9,6 +9,7 @@ published as individual NuGet packages. Each project corresponds to one NuGet pa
 |---|---|---|
 | `SharedCode.Core` | `SharedCode.Core` | Core utilities: extensions, specifications, domain primitives, text, calendar, security, threading, reactive |
 | `SharedCode.Core.Tests` | *(test only)* | Unit tests for `SharedCode.Core` |
+| `SharedCode.Data.Tests` | *(test only)* | Unit tests for `SharedCode.Data` |
 | `SharedCode.Data` | `SharedCode.Data` | Data access abstractions and helpers (repository pattern, paging, query results) |
 | `SharedCode.Data.CosmosDb` | `SharedCode.Data.CosmosDb` | Azure Cosmos DB integration |
 | `SharedCode.Data.EntityFramework` | `SharedCode.Data.EntityFramework` | Entity Framework Core integration (auditable contexts, EF repository, specifications) |
@@ -37,7 +38,7 @@ dotnet test --logger GitHubActions --verbosity normal SharedCode.sln
 - **Target frameworks**:
   - Primary/current: `.NET 10` (`net10.0`)
   - Compatibility targets: `.NET 9` (`net9.0`), `.NET 8` (`net8.0`), and `.NET Standard 2.0/2.1` where applicable
-- **Language version**: `preview` (latest C# features enabled)
+- **Language version**: `preview` (latest C# features enabled — C# 13 and beyond)
 - **Nullable reference types**: enabled (`<Nullable>enable</Nullable>`)
 - **Implicit usings**: enabled
 - **Warnings as errors**: all warnings are treated as errors
@@ -93,6 +94,33 @@ public static DateTime AddBusinessDays(this DateTime @this, int days) { ... }
 - Prefer `ArgumentException.ThrowIfNullOrEmpty(param)` for strings (.NET 7+)
 - When targeting older frameworks via polyfill, wrap with `#if NET6_0_OR_GREATER`
 
+### C# 13 / .NET 10 Modern Features
+
+Use these features wherever they improve clarity. The solution targets `LangVersion: preview`, so
+all C# 13 features are available:
+
+- **Collection expressions** (`[..]`) — prefer over `new List<T> { }` or `new T[] { }` literals
+  ```csharp
+  string[] names = ["Alice", "Bob"];
+  List<int> ids = [1, 2, 3];
+  ```
+- **`params ReadOnlySpan<T>`** — prefer for methods that accept a variable number of arguments when
+  performance matters and heap allocation should be avoided
+- **Primary constructors** — prefer for simple types that store injected dependencies:
+  ```csharp
+  public sealed class MyService(ILogger<MyService> logger) { ... }
+  ```
+- **`field` keyword** — use inside property accessors to access the auto-generated backing field
+  without declaring it explicitly (C# 13 preview):
+  ```csharp
+  public string Name
+  {
+      get;
+      set => field = value.Trim();
+  }
+  ```
+- **`allows ref struct`** — add to generic constraints when the type parameter may be a ref struct
+
 ### Code Analysis Suppressions
 
 - Suppress with `[SuppressMessage("Category", "RuleId:Title", Justification = "reason")]`
@@ -135,14 +163,22 @@ Services implement `IDependencyRegister` to self-register via assembly scanning
 
 ## Testing Conventions
 
-Unit tests live in `SharedCode.Core.Tests/` and follow these rules:
+Unit tests live in `SharedCode.Core.Tests/` and `SharedCode.Data.Tests/` and follow these rules:
 
-- **Framework**: MSTest (`[TestClass]`, `[TestMethod]`, `[DataRow]`)
+- **Framework**: MSTest (`[TestClass]`, `[TestMethod]`, `[DataRow]`, `[DataTestMethod]`)
 - **Assertions**: AwesomeAssertions
 - **Pattern**: Arrange / Act / Assert with blank lines separating each block
 - **File location**: mirror the source structure
   (e.g., `Calendar/DateTimeExtensionsTests.cs` for `Calendar/DateTimeExtensions.cs`)
-- Suppress `CA1515` on test classes — MSTest requires them to be `public`
+- `CA1515` (`public` types as internal) is suppressed at the test-project level via `.editorconfig` — MSTest requires test classes to be `public`
+
+### `SharedCode.Data.Tests`
+
+The `SharedCode.Data.Tests` project mirrors the structure of `SharedCode.Data` and tests:
+
+- Repository base types (`QueryRepository`, `CommandRepository`)
+- Paging helpers (`PagingDescriptor`, `PageBoundry`)
+- Query result types (`QueryResult`)
 
 ## Shared Build Configuration
 

.github/prompts/add-test-class.prompt.md

@@ -0,0 +1,107 @@
+---
+mode: edit
+description: Add a new MSTest test class for a SharedCode source file following project conventions.
+---
+
+# Add a Test Class
+
+Add a new MSTest test class that exercises a source file in the SharedCode library.
+
+## Steps
+
+1. **Identify the source file** you want to test and locate it in the solution.
+
+2. **Choose the right test project**
+
+   | Source project | Test project |
+   |---|---|
+   | `SharedCode.Core` | `SharedCode.Core.Tests` |
+   | `SharedCode.Data` | `SharedCode.Data.Tests` |
+
+3. **Mirror the source folder structure**
+
+   Place the new file in the same relative subfolder as the source:
+
+   | Source file | Test file |
+   |---|---|
+   | `SharedCode.Core/Calendar/DateTimeExtensions.cs` | `SharedCode.Core.Tests/Calendar/DateTimeExtensionsTests.cs` |
+   | `SharedCode.Data/Paging/PagingDescriptor.cs` | `SharedCode.Data.Tests/PagingDescriptorTests.cs` |
+
+4. **Write the test class** following these rules:
+   - Annotate with `[TestClass]`
+   - Do **not** add a per-class `CA1515` suppression — it is already disabled at the project level via `.editorconfig`
+   - Use `[TestMethod]` for single-scenario tests
+   - Use `[DataTestMethod]` + `[DataRow(...)]` for parameterized tests
+   - Follow the **Arrange / Act / Assert** pattern with blank lines separating each block
+   - Use **MSTest assertions** (`Assert.AreEqual`, `Assert.IsTrue`, `Assert.IsNotNull`, `Assert.ThrowsExactly`)
+   - Name test methods as `<MemberUnderTest>_<Scenario>_<ExpectedOutcome>`
+
+5. **Verify zero warnings**: `dotnet build SharedCode.sln`
+
+## Template — single-scenario test
+
+```csharp
+namespace SharedCode.Tests.<Folder>;
+
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+
+/// <summary>
+/// Tests for <see cref="<TypeUnderTest>" />.
+/// </summary>
+[TestClass]
+public class <TypeUnderTest>Tests
+{
+    /// <summary>
+    /// Tests that <Member> does [expected behavior].
+    /// </summary>
+    [TestMethod]
+    public void <Member>_<Scenario>_<ExpectedOutcome>()
+    {
+        // Arrange
+        var sut = <create instance or value>;
+
+        // Act
+        var result = sut.<Member>(...);
+
+        // Assert
+        Assert.AreEqual(<expected>, result);
+    }
+}
+```
+
+## Template — parameterized test
+
+```csharp
+/// <summary>
+/// Tests that <Member> returns the expected result for various inputs.
+/// </summary>
+[DataTestMethod]
+[DataRow(<input1>, <expected1>)]
+[DataRow(<input2>, <expected2>)]
+public void <Member>_<Scenario>_<ExpectedOutcome>(<InputType> input, <ExpectedType> expected)
+{
+    // Arrange
+    var sut = <create instance or value>;
+
+    // Act
+    var result = sut.<Member>(input);
+
+    // Assert
+    Assert.AreEqual(expected, result);
+}
+```
+
+## Template — exception test
+
+```csharp
+/// <summary>
+/// Tests that <Member> throws <ExceptionType> when [condition].
+/// </summary>
+[TestMethod]
+public void <Member>_<Condition>_Throws<ExceptionType>()
+{
+    // Act / Assert
+    _ = Assert.ThrowsExactly<<ExceptionType>>(
+        () => <sut>.<Member>(<args>));
+}
+```

.github/prompts/create-module.prompt.md

@@ -27,7 +27,7 @@ belong here.
     <Description>A library of [short description] shared for free use to help with common scenarios.</Description>
     <PackageTags>shared code, c#, [relevant tags]</PackageTags>
     <RootNamespace>SharedCode.<ModuleName></RootNamespace>
-    <TargetFrameworks>net9.0;net10.0</TargetFrameworks>
+    <TargetFrameworks>net8.0;net9.0;net10.0</TargetFrameworks>
   </PropertyGroup>
 
   <ItemGroup>

.github/prompts/improve-coverage.prompt.md

@@ -0,0 +1,70 @@
+---
+mode: edit
+description: Identify untested public members and add test coverage for them.
+---
+
+# Improve Test Coverage
+
+Identify public members in a SharedCode source file (or folder) that have no test coverage
+and add tests for them.
+
+## Process
+
+### 1 — Identify what is missing
+
+For each `.cs` file in the source project:
+
+1. List every `public` method, property, and indexer.
+2. Open the corresponding `*Tests.cs` file in the test project (if it exists).
+3. Note every member that has **no** `[TestMethod]` exercising it.
+4. If no test file exists at all, every public member needs coverage.
+
+### 2 — Prioritize
+
+Cover members in this order:
+1. Pure logic methods (no I/O or infrastructure) — easiest to test
+2. Guard-clause paths (`ArgumentNullException`, `ArgumentException`)
+3. Edge cases (empty collections, null-optional parameters, boundary values)
+4. Happy paths for remaining members
+
+### 3 — Write the tests
+
+Follow the conventions in `add-test-class.prompt.md`:
+- `[TestMethod]` for single scenarios
+- `[DataRow]` for parameterized scenarios
+- MSTest assertions (`Assert.AreEqual`, `Assert.IsTrue`, `Assert.ThrowsExactly`)
+- Arrange / Act / Assert blocks separated by blank lines
+
+### 4 — Verify
+
+```bash
+dotnet test SharedCode.sln
+```
+
+Zero failures required before merging.
+
+## Checklist per source file
+
+Run through these questions for each public member:
+
+- [ ] Is there a happy-path test?
+- [ ] Is there a null-argument test (if the member accepts reference-type parameters)?
+- [ ] Is there a boundary/edge-case test (empty string, zero, `int.MaxValue`, etc.)?
+- [ ] Is the test parameterized with `[DataRow]` instead of repeated copy-paste?
+
+## Common coverage gaps in this solution
+
+| Source file | Members typically missing coverage |
+|---|---|
+| `AssemblyExtensions.cs` | `GetAttribute<T>` (found / not found) |
+| `EventHandlerExtensions.cs` | `Raise` overloads (null handler, non-null handler) |
+| `Extensions.cs` | `IsBetween`, `In`, `IfNotNull`, `IsNull<T>`, `ChangeType<T>` |
+| `FunctionExtensions.cs` | `Memoize` (cache hit, cache miss) |
+| `TypeExtensions.cs` | `GetDisplayName`, `IsNullable`, `IsSubclassOfRawGeneric` |
+| `PropertySupport.cs` | `ExtractPropertyName` |
+| `Linq/` | All `IEnumerable<T>` extension methods |
+| `Security/` | Hashing / encryption helpers |
+| `Text/` | All string extension methods |
+| `Threading/` | All task/threading helpers |
+| `Domain/` | `ValueObject` equality |
+| `Specifications/` | `InMemorySpecificationEvaluator` |

.github/prompts/maintain-copilot-instructions.prompt.md

@@ -25,14 +25,16 @@ Run this prompt after adding new modules, changing conventions, or updating the
 
 - [ ] `add-extension-method.prompt.md` — namespace table is complete and templates compile
 - [ ] `add-specification.prompt.md` — builder API still matches `ISpecificationBuilder<T>`
+- [ ] `add-test-class.prompt.md` — assertion style matches the project's test conventions
 - [ ] `fix-code-analysis.prompt.md` — rule table covers the analyzers actually in use
 - [ ] `create-module.prompt.md` — scaffolding steps still match the solution structure
+- [ ] `improve-coverage.prompt.md` — coverage gap table is accurate
 - [ ] Each prompt's `description` front-matter field is accurate
 
 ### `.vscode/mcp.json`
 
 - [ ] Listed MCP servers are still current and useful
-- [ ] Docker image tags or npx package versions are up to date
+- [ ] npx package versions are up to date
 - [ ] Any new MCP servers that would improve development tasks should be added
 
 ## Process

.github/workflows/dotnet.yml

@@ -22,4 +22,12 @@ jobs:
         dotnet-version: 10.0.x
 
     - name: Run tests
-      run: dotnet test --logger GitHubActions SharedCode.sln
+      run: dotnet test --logger GitHubActions --collect:"XPlat Code Coverage" SharedCode.sln
+
+    - name: Upload coverage reports
+      if: always()
+      uses: actions/upload-artifact@v4
+      with:
+        name: coverage-reports
+        path: '**/coverage.cobertura.xml'
+        if-no-files-found: ignore

.github/workflows/maintain-copilot-instructions.yml

@@ -50,6 +50,22 @@ jobs:
             fi
           done <<< "$projects"
 
+          # Check that required prompt files exist
+          required_prompts=(
+            ".github/prompts/add-extension-method.prompt.md"
+            ".github/prompts/add-specification.prompt.md"
+            ".github/prompts/add-test-class.prompt.md"
+            ".github/prompts/create-module.prompt.md"
+            ".github/prompts/fix-code-analysis.prompt.md"
+            ".github/prompts/improve-coverage.prompt.md"
+            ".github/prompts/maintain-copilot-instructions.prompt.md"
+          )
+          for prompt in "${required_prompts[@]}"; do
+            if [[ ! -f "$prompt" ]]; then
+              missing_list="${missing_list}\n- Missing prompt: \`${prompt}\`"
+            fi
+          done
+
           if [[ -n "$missing_list" ]]; then
             echo "has_missing=true"  >> "$GITHUB_OUTPUT"
           else
@@ -74,18 +90,18 @@ jobs:
             const body = [
               '## Copilot Instructions May Be Outdated',
               '',
-              'The following projects are present in `SharedCode.sln` but are not yet',
-              'documented in `.github/copilot-instructions.md`:',
+              'The following projects or prompt files are missing from the Copilot configuration:',
               '',
               missing,
               '',
               '### What to do',
               '',
-              '1. Open `.github/copilot-instructions.md` and add the missing projects to',
+              '1. Open `.github/copilot-instructions.md` and add any missing projects to',
               '   the module table.',
-              '2. Use the prompt at `.github/prompts/maintain-copilot-instructions.prompt.md`',
+              '2. Ensure all required prompt files exist under `.github/prompts/`.',
+              '3. Use the prompt at `.github/prompts/maintain-copilot-instructions.prompt.md`',
               '   to guide a full review of all Copilot configuration files.',
-              '3. Close this issue once the instructions are up to date.',
+              '4. Close this issue once the instructions are up to date.',
             ].join('\n');
 
             const label = 'copilot-instructions';

.vscode/mcp.json

@@ -9,18 +9,28 @@
   ],
   "servers": {
     "github": {
-      "command": "docker",
+      "command": "npx",
       "args": [
-        "run",
-        "--interactive",
-        "--rm",
-        "--env",
-        "GITHUB_PERSONAL_ACCESS_TOKEN",
-        "ghcr.io/github/github-mcp-server"
+        "-y",
+        "@github/github-mcp-server"
       ],
       "env": {
         "GITHUB_PERSONAL_ACCESS_TOKEN": "${input:github-token}"
       }
+    },
+    "sequential-thinking": {
+      "command": "npx",
+      "args": [
+        "-y",
+        "@modelcontextprotocol/server-sequential-thinking"
+      ]
+    },
+    "dotnet-skills": {
+      "command": "npx",
+      "args": [
+        "-y",
+        "@microsoft/dotnet-mcp-server"
+      ]
     }
   }
 }

Directory.Build.props

@@ -107,8 +107,8 @@
         <RunAnalyzersDuringBuild>false</RunAnalyzersDuringBuild>
     </PropertyGroup>
     <Target Name="SetSourceRevisionId" BeforeTargets="InitializeSourceControlInformation">
-        <Exec Command="git describe --long --always --dirty --exclude=* --abbrev=8" ConsoleToMSBuild="True" IgnoreExitCode="False">
-            <!--<Output PropertyName="SourceRevisionId" TaskParameter="ConsoleOutput" />-->
+        <Exec Command="git describe --long --always --dirty --exclude=* --abbrev=8" ConsoleToMSBuild="True" IgnoreExitCode="True">
+            <Output PropertyName="SourceRevisionId" TaskParameter="ConsoleOutput" />
         </Exec>
     </Target>
 </Project>