Add support for custom database adapters and update documentation

README.md

@@ -51,6 +51,24 @@ using (var conn = new NpgsqlConnection("ConnectionString"))
 }
 ```
 
+## Custom Database Adapter
+
+If you need to support a database that is not included, or want to provide your own implementation of `IDbAdapter`, you can do so:
+
+```csharp
+var options = new RespawnerOptions
+{
+    DbAdapter = new MyCustomDbAdapter()
+};
+var respawner = await Respawner.CreateAsync(connection, options);
+```
+
+ `myCustomDbAdapter` should implement the `IDbAdapter` interface.
+
+This allows you to extend Respawn for any database or custom logic you require.
+
+For a very simple example of a custom IDbAdapter being used see the [SqliteCustomAdapterTests](Respawn.DatabaseTests\SqliteCustomAdapterTests.cs)
+
 ## How does it work?
 Respawn examines the SQL metadata intelligently to build a deterministic order of tables to delete based on foreign key relationships between tables. It navigates these relationships to build a DELETE script starting with the tables with no relationships and moving inwards until all tables are accounted for.
 

Respawn.DatabaseTests/Respawn.DatabaseTests.csproj

@@ -6,6 +6,7 @@
   </PropertyGroup>
   <ItemGroup>
     <PackageReference Include="IBM.Data.DB2.Core" Version="3.1.0.500" />
+    <PackageReference Include="Microsoft.Data.Sqlite" Version="9.0.5" />
     <PackageReference Include="MySql.Data" Version="9.2.0" />
     <PackageReference Include="Npgsql" Version="9.0.3" />
     <PackageReference Include="NPoco.SqlServer" Version="5.7.1" />

Respawn.DatabaseTests/SqliteCustomAdapterTests.cs

@@ -0,0 +1,61 @@
+using System;
+using System.Data.Common;
+using System.Threading.Tasks;
+using Microsoft.Data.Sqlite;
+using Respawn;
+using Respawn.Graph;
+using Shouldly;
+using Xunit;
+
+namespace Respawn.DatabaseTests
+{
+  public class CustomSqliteAdapter : IDbAdapter
+  {
+    public string BuildDeleteCommandText(GraphBuilder graph, RespawnerOptions options)
+        => "DELETE FROM TestTable;";
+    public string BuildReseedSql(System.Collections.Generic.IEnumerable<Table> tables) => null;
+    public string BuildTableCommandText(RespawnerOptions options) => "SELECT NULL, name FROM sqlite_master WHERE type='table' AND name='TestTable';";
+    public string BuildRelationshipCommandText(RespawnerOptions options) => "SELECT NULL, 'TestTable', NULL, 'TestTable', 'PK_TestTable';";
+    public string BuildTemporalTableCommandText(RespawnerOptions options) => "SELECT NULL, NULL, NULL, NULL;";
+    public string BuildTurnOffSystemVersioningCommandText(System.Collections.Generic.IEnumerable<TemporalTable> tables) => string.Empty;
+    public string BuildTurnOnSystemVersioningCommandText(System.Collections.Generic.IEnumerable<TemporalTable> tables) => string.Empty;
+    public Task<bool> CheckSupportsTemporalTables(DbConnection connection) => Task.FromResult(false);
+  }
+
+  public class SqliteCustomAdapterTests
+  {
+    [Fact]
+    public async Task ShouldResetTableWithCustomAdapter()
+    {
+      var connectionString = "Data Source=:memory:";
+      await using var conn = new SqliteConnection(connectionString);
+      await conn.OpenAsync();
+
+      var createTable = conn.CreateCommand();
+      createTable.CommandText = "CREATE TABLE TestTable (Id INTEGER PRIMARY KEY, Name TEXT);";
+      await createTable.ExecuteNonQueryAsync();
+
+      var insert = conn.CreateCommand();
+      insert.CommandText = "INSERT INTO TestTable (Name) VALUES ('foo');";
+      await insert.ExecuteNonQueryAsync();
+
+      // Confirm row exists
+      var countCmd = conn.CreateCommand();
+      countCmd.CommandText = "SELECT COUNT(*) FROM TestTable;";
+      var countBefore = (long)await countCmd.ExecuteScalarAsync();
+      countBefore.ShouldBe(1);
+
+      // Use custom adapter
+      var options = new RespawnerOptions
+      {
+        DbAdapter = new CustomSqliteAdapter(),
+      };
+      var respawner = await Respawner.CreateAsync(conn, options);
+      await respawner.ResetAsync(conn);
+
+      // Confirm table is empty
+      var countAfter = (long)await countCmd.ExecuteScalarAsync();
+      countAfter.ShouldBe(0);
+    }
+  }
+}