Fix GraphQL aggregation features disabled when runtime.graphql config section is absent

[Copilot]

Why make this change?

GraphQL aggregation features (groupBy, sum, avg, min, max, count) were silently disabled for users whose config lacked an explicit runtime.graphql section, even though EnableAggregation defaults to true.

What is this change?

Bug fix: RuntimeConfig.EnableAggregation logic inversion

The property used && logic, returning false when Runtime or Runtime.GraphQL was null. This is inconsistent with every analogous property (e.g. IsGraphQLEnabled) which use || logic to treat absence as "use default (enabled)":

// Before (broken): returns false when runtime.graphql section is absent
public bool EnableAggregation =>
    Runtime is not null &&
    Runtime.GraphQL is not null &&
    Runtime.GraphQL.EnableAggregation;

// After (fixed): returns true when section is absent, consistent with IsGraphQLEnabled
public bool EnableAggregation =>
    Runtime is null ||
    Runtime.GraphQL is null ||
    Runtime.GraphQL.EnableAggregation;

Additional fixes:

• GraphQLSchemaCreator.OnConfigChanged now updates _isAggregationEnabled on hot-reload (was omitted, causing stale state)
• schemas/dab.draft.schema.json: added enable-aggregation to runtime.graphql properties — it was missing despite additionalProperties: false, meaning any config explicitly setting the flag would fail schema validation

Test refactoring (per code review feedback):

• Extracted a LoadConfig private helper in RuntimeConfigLoaderTests to eliminate repeated mock-filesystem setup across all EnableAggregation tests
• Merged EnableAggregation_WhenExplicitlyDisabled_ReturnsFalse and EnableAggregation_WhenExplicitlyEnabled_ReturnsTrue into a single parameterized [DataTestMethod] (EnableAggregation_WhenExplicitlySet_ReturnsConfiguredValue) using [DataRow(true)] and [DataRow(false)]
• Merged Build_WithMssqlAndAggregationEnabled_AddsGroupByToConnectionType and Build_WithPostgreSqlAndAggregationEnabled_DoesNotAddGroupByToConnectionType into a single parameterized [DataTestMethod] (Build_WithAggregationEnabled_GroupByPresenceMatchesDatabaseSupport) covering MSSQL, DWSQL (groupBy present), PostgreSQL, and MySQL (groupBy absent)

How was this tested?

• Integration Tests
• Unit Tests
  • RuntimeConfigLoaderTests: EnableAggregation defaults to true when runtime or runtime.graphql sections are absent; a single parameterized test (EnableAggregation_WhenExplicitlySet_ReturnsConfiguredValue) covers both true and false explicit values using [DataRow]. A shared LoadConfig helper eliminates repeated mock-filesystem setup.
  • QueryBuilderTests: a single parameterized test (Build_WithAggregationEnabled_GroupByPresenceMatchesDatabaseSupport) covers MSSQL and DWSQL (groupBy present) and PostgreSQL and MySQL (groupBy absent), plus a test confirming groupBy is omitted when aggregation is disabled.

Sample Request(s)

With a config that has no explicit runtime.graphql section, the following now works as expected for MSSQL/DWSQL entities:

{
  books {
    groupBy(fields: [price]) {
      fields { price }
      aggregations {
        count
        sum(field: price)
        avg(field: price)
        max(field: price)
        min(field: price)
      }
    }
  }
}

[Copilot]

Pull request overview

Fixes a regression where GraphQL aggregation features were incorrectly disabled when the runtime.graphql config section was omitted, despite aggregation defaulting to enabled.

Changes:

• Corrected RuntimeConfig.EnableAggregation defaulting behavior to treat missing runtime / runtime.graphql as “enabled”.
• Updated GraphQLSchemaCreator hot-reload handling to refresh the aggregation-enabled flag.
• Extended dab.draft.schema.json to allow runtime.graphql.enable-aggregation, and added unit tests covering defaults and schema surface area (groupBy presence).

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/Service.Tests/GraphQLBuilder/QueryBuilderTests.cs	Adds unit tests verifying groupBy is present/absent based on aggregation enablement and supported DB types.
src/Service.Tests/Configuration/RuntimeConfigLoaderTests.cs	Adds unit tests validating EnableAggregation defaults and honoring explicit enable-aggregation.
src/Core/Services/GraphQLSchemaCreator.cs	Updates hot-reload path to refresh _isAggregationEnabled from latest runtime config.
src/Config/ObjectModel/RuntimeConfig.cs	Fixes EnableAggregation logic to default to true when config sections are absent; updates doc comment accordingly.
schemas/dab.draft.schema.json	Adds runtime.graphql.enable-aggregation to schema properties so configs can validate when explicitly set.

[anushakolan]

The PR needs refactoring to reduce unnecessary repetition. Apart from this looks good.