Share the time spent by EF Core migration across independent tests or between same test runs

In my .NET 8 app, migrating my contexts takes 10 seconds on my machine. And since I run hundreds of independent xUnit tests that each have their own databases, the complete suite of tests ends up being too slow, even with parallelism.

I wonder what EF Core does so I can cache it as it's a common step to all my tests.

Any ideas? Maybe a pool of databases that the tests could pick, clear and reuse in parallel?

I ended up having a finite stack of unique database names. I pop a new name when needed and at the end of each test I clear the database to then recycle the database name by pushing it back to the stack.

public class WebApplicationFactoryHelper
{
    private static readonly ConcurrentStack<Guid> Suffixes = new([
        Guid.Parse("7a00615f-c58a-4d4f-a0b7-081a881f58ac"),
        Guid.Parse("2ff693ef-e0ba-4430-bfc1-ac1a9288c99b"),
        Guid.Parse("23ec38d9-7b9c-46b5-9fcb-861f76dd500b"),
        Guid.Parse("7cd51fb0-3a8e-4828-bab1-9d87c2703f1a"),
        ...
    ]);

public static async Task RecycleDb(Guid suffix)
{
    var connectionString = $"Server=localhost;Database={suffix};Trusted_Connection=True;TrustServerCertificate=Yes;MultipleActiveResultSets=true";
    const string sql = """
                       
                       EXEC sp_MSForEachTable 
                           @command1 = '
                           SET QUOTED_IDENTIFIER ON;
                        IF ''?'' <> ''[dbo].[__EFMigrationsHistory]''
                           BEGIN 
                               IF ''?'' = ''[dbo].[AspNetUsers]''
                               BEGIN 
                                   DELETE FROM dbo.AspNetUsers WHERE UserName <> ''SpecificSeededUserName''
                               END
                               ELSE 
                               BEGIN 
                                   DELETE FROM ? 
                               END
                           END'
                       """;
    await using var connection = new SqlConnection(connectionString);
    await connection.ExecuteAsync(sql);
    Suffixes.Push(suffix);
}

public static Guid ConfigureDbSync(IServiceCollection serviceCollection)
{
    var suffix = Suffixes.TryPop(out var result) ? result : throw new Exception("not enough dbs");
    var connectionString = $"Server=localhost;Database={suffix};Trusted_Connection=True;TrustServerCertificate=Yes;MultipleActiveResultSets=true";
    serviceCollection.Replace(new ServiceDescriptor(typeof(SqlConnection), _ => new SqlConnection(connectionString), ServiceLifetime.Scoped));
    return suffix;
}

}