EF Core: Implement specification/compliance tests

[DaveRMaltby]

Summary

The EF Core providers do not run the standard EF Core specification tests provided by Microsoft. These tests verify that a provider correctly implements the EF Core contract.

What's Needed

1. Test project referencing Microsoft.EntityFrameworkCore.Relational.Specification.Tests
2. Test fixtures implementing RelationalTestStoreFactory for each file provider
3. RelationalComplianceTestBase subclass that enumerates which test classes are covered
4. Provider-specific test store that creates/destroys file-based databases for test isolation

Key Test Suites to Implement

• QueryTestBase — LINQ query translation correctness
• UpdatesTestBase — INSERT/UPDATE/DELETE via EF Core
• TransactionTestBase — transaction behavior
• MigrationsTestBase — migration operations (once migrations are implemented)
• ScaffoldingTestBase — reverse engineering correctness

Why This Matters

Without specification tests, there's no systematic way to verify provider correctness. Consumers may encounter subtle bugs where EF Core operations produce incorrect results or silently fail.

Standard Reference

• Testing against the specification tests
• The Sqlite provider's test project is a good model for a lightweight provider