Fix: Guid PKs bulk-inserted as NULL without explicit ValueGeneratedNever()

[Copilot]

EF Core defaults Guid primary keys to ValueGenerated.OnAdd (client-side generation). The library was treating all ValueGenerated != Never properties as "database-generated" and excluding them from the INSERT column list, causing NULL to be inserted for Guid PKs unless ValueGeneratedNever() was explicitly configured.

Changes

• ColumnMetadata.cs: IsGenerated no longer marks Guid/Guid? columns as generated unless they carry an explicit SQL default expression (GetDefaultValueSql()), are computed columns (GetComputedColumnSql()), or have a CLR-level default explicitly configured via HasDefaultValue(...) (detected via FindAnnotation(RelationalAnnotationNames.DefaultValue)). Non-Guid auto-increment columns (SQL Server IDENTITY, SQLite integer PK) are unaffected.

• TestDbContext.cs: Removed the ValueGeneratedNever() workaround from TestEntityWithGuidId — the entity now works correctly by default.

• BasicTestsBase.cs: Updated InsertEntities_WithGeneratedGuidId to remove the CopyGeneratedColumns = true workaround and assert that application-assigned Guid values are preserved end-to-end.

• MergeTestsBase.cs: Updated InsertEntities_MultipleTimes_WithGuidId to assert that the application-assigned Guid Id is preserved through the merge/on-conflict path (removed .Excluding(e => e.Id) from the equivalence check).

Before / After

// This previously required .ValueGeneratedNever() in OnModelCreating — now works as-is
public class MyEntity
{
    public Guid Id { get; set; }   // assigned via Guid.NewGuid()
}

await db.ExecuteBulkInsertAsync(entities); // was: NULL inserted into Id
                                           // now:  assigned Guid preserved

A Guid column with an explicit database default (e.g. HasDefaultValueSql("NEWID()") or HasDefaultValue(someGuid)) continues to be treated as generated and excluded from INSERT by default.

[Copilot]

Pull request overview

This PR fixes bulk insert handling for EF Core’s default Guid primary key metadata by treating application-assigned Guid keys as insertable unless they have explicit database generation metadata.

Changes:

• Refines ColumnMetadata.IsGenerated so default Guid/Guid? ValueGenerated.OnAdd columns are not automatically excluded from inserts.
• Removes the test-only ValueGeneratedNever() workaround for TestEntityWithGuidId.
• Updates the basic Guid key insert test to assert the assigned Guid IDs are preserved.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
src/PhenX.EntityFrameworkCore.BulkInsert/Metadata/ColumnMetadata.cs	Updates generated-column detection for Guid/Guid? properties.
tests/PhenX.EntityFrameworkCore.BulkInsert.Tests/DbContext/TestDbContext.cs	Removes explicit Guid key generation override from test model configuration.
tests/PhenX.EntityFrameworkCore.BulkInsert.Tests/Tests/Basic/BasicTestsBase.cs	Adjusts Guid key bulk insert test expectations and options.

[PhenX]

@copilot take the review into account

[Copilot]

@copilot take the review into account

Both review points are addressed:

1. ColumnMetadata.cs — HasDefaultValue(...) gap (commit): The initial fix used property.GetDefaultValue() != null, but investigation showed this returns Guid.Empty for all Guid properties even without any explicit configuration — which would have broken the fix entirely. The correct check is property.FindAnnotation(RelationalAnnotationNames.DefaultValue) != null, which is only set when HasDefaultValue(...) is explicitly called in OnModelCreating. The IsGenerated condition for Guid columns is now:

   property.GetDefaultValueSql() != null       // HasDefaultValueSql("NEWID()")
   || property.GetComputedColumnSql() != null  // computed column
   || property.FindAnnotation(RelationalAnnotationNames.DefaultValue) != null  // HasDefaultValue(someGuid)

   Plain Guid PKs (client-side generation) have none of these → included in INSERT as intended.

2. MergeTestsBase.cs — merge path coverage: Removed .Excluding(e => e.Id) from InsertEntities_MultipleTimes_WithGuidId so the merge test now asserts the full entity (including the Guid Id) is preserved after an on-conflict update.