feat(tests): add database test infrastructure

Add DatabaseTestBase.cs with xUnit Collection for test isolation:
- DatabaseTestCollection disables parallel execution
- DatabaseTestFixture verifies database connectivity
- DatabaseTestBase provides connection and cleanup helpers
- InsertTestSearchAsync for creating test data with SearchCriteria
- InsertTestSearchWithRawCriteriaAsync for testing invalid JSON scenarios

Also adds required packages: Dapper, FluentAssertions, Microsoft.Data.SqlClient

NEW/tests/JdeScoping.Database.Tests/Infrastructure/DatabaseTestBase.cs

@@ -0,0 +1,98 @@
+using System.Text.Json;
+using Dapper;
+using JdeScoping.Core.Models.Search;
+using Microsoft.Data.SqlClient;
+
+namespace JdeScoping.Database.Tests.Infrastructure;
+
+/// <summary>
+/// xUnit Collection definition to disable parallel execution for database tests.
+/// All test classes using [Collection("DatabaseTests")] run sequentially.
+/// </summary>
+[CollectionDefinition("DatabaseTests")]
+public class DatabaseTestCollection : ICollectionFixture<DatabaseTestFixture>
+{
+}
+
+/// <summary>
+/// Shared fixture for database tests. Ensures database is available.
+/// </summary>
+public class DatabaseTestFixture : IAsyncLifetime
+{
+    /// <summary>
+    /// Connection string for the test database.
+    /// Uses SA credentials from db_info.md for local development.
+    /// </summary>
+    public const string ConnectionString =
+        "Server=localhost,1434;Database=ScopingTool;User Id=sa;Password=ScopingTool_SA_2024Dev;TrustServerCertificate=true";
+
+    public async Task InitializeAsync()
+    {
+        // Verify database is accessible
+        using var connection = new SqlConnection(ConnectionString);
+        await connection.OpenAsync();
+    }
+
+    public Task DisposeAsync() => Task.CompletedTask;
+}
+
+/// <summary>
+/// Base class for database function tests.
+/// Each test gets its own connection and cleans up created data.
+/// </summary>
+[Collection("DatabaseTests")]
+public abstract class DatabaseTestBase : IAsyncLifetime
+{
+    protected SqlConnection Connection { get; private set; } = null!;
+
+    private readonly List<int> _createdSearchIds = [];
+
+    public async Task InitializeAsync()
+    {
+        Connection = new SqlConnection(DatabaseTestFixture.ConnectionString);
+        await Connection.OpenAsync();
+    }
+
+    public async Task DisposeAsync()
+    {
+        // Clean up test data
+        foreach (var id in _createdSearchIds)
+        {
+            await Connection.ExecuteAsync("DELETE FROM dbo.Search WHERE ID = @Id", new { Id = id });
+        }
+
+        await Connection.DisposeAsync();
+    }
+
+    /// <summary>
+    /// Insert a test search with the given criteria and return the ID.
+    /// </summary>
+    protected async Task<int> InsertTestSearchAsync(SearchCriteria criteria, string userName = "testuser", string name = "Test Search")
+    {
+        var criteriaJson = JsonSerializer.Serialize(criteria);
+
+        var id = await Connection.QuerySingleAsync<int>(
+            @"INSERT INTO dbo.Search (UserName, Name, Status, Criteria)
+              OUTPUT INSERTED.ID
+              VALUES (@UserName, @Name, 0, @Criteria)",
+            new { UserName = userName, Name = name, Criteria = criteriaJson });
+
+        _createdSearchIds.Add(id);
+        return id;
+    }
+
+    /// <summary>
+    /// Insert a test search with raw criteria JSON (for testing invalid JSON scenarios).
+    /// </summary>
+    protected async Task<int> InsertTestSearchWithRawCriteriaAsync(string? criteriaJson, string userName = "testuser", string name = "Test Search")
+    {
+        var id = await Connection.QuerySingleAsync<int>(
+            @"INSERT INTO dbo.Search (UserName, Name, Status, Criteria)
+              OUTPUT INSERTED.ID
+              VALUES (@UserName, @Name, 0, @Criteria)",
+            new { UserName = userName, Name = name, Criteria = criteriaJson });
+
+        _createdSearchIds.Add(id);
+        return id;
+    }
+}

NEW/tests/JdeScoping.Database.Tests/JdeScoping.Database.Tests.csproj

@@ -5,10 +5,14 @@
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
     <IsPackable>false</IsPackable>
+    <IsTestProject>true</IsTestProject>
   </PropertyGroup>
 
   <ItemGroup>
     <PackageReference Include="coverlet.collector" Version="6.0.4" />
+    <PackageReference Include="Dapper" Version="2.1.35" />
+    <PackageReference Include="FluentAssertions" Version="6.12.0" />
+    <PackageReference Include="Microsoft.Data.SqlClient" Version="5.2.2" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.14.1" />
     <PackageReference Include="NSubstitute" Version="5.3.0" />
     <PackageReference Include="Shouldly" Version="4.3.0" />
@@ -21,6 +25,7 @@
   </ItemGroup>
 
   <ItemGroup>
+    <ProjectReference Include="..\..\src\JdeScoping.Core\JdeScoping.Core.csproj" />
     <ProjectReference Include="..\..\src\JdeScoping.Database\JdeScoping.Database.csproj" />
   </ItemGroup>
 

NEW/tests/JdeScoping.Database.Tests/Placeholder.cs

@@ -1,8 +0,0 @@
-// This file exists to ensure the test project compiles.
-// Add tests here as needed.
-namespace JdeScoping.Database.Tests;
-
-public class Placeholder
-{
-    // Tests will be added here
-}