refactor(sqlserver): accept collation expression in validation

Adapt COLLATE validation to consume the full CollateExpression while preserving SQL Server DATABASE_DEFAULT keyword handling.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Author: vistart

src/rhosocial/activerecord/backend/impl/sqlserver/dialect.py

@@ -87,7 +87,7 @@
 
 if TYPE_CHECKING:
     from rhosocial.activerecord.backend.expression import bases
-    from rhosocial.activerecord.backend.expression.collation import CollationName
+    from rhosocial.activerecord.backend.expression.collation import CollateExpression
     from rhosocial.activerecord.backend.expression.advanced_functions import ArrayExpression, OrderedSetAggregation, JSONExpression
     from rhosocial.activerecord.backend.expression.graph import MatchClause
     from rhosocial.activerecord.backend.expression.query_parts import (
@@ -278,13 +278,18 @@ def supports_collate_expression(self) -> bool:
         """SQL Server supports expression-level COLLATE."""
         return True
 
-    def validate_collation_name(self, collation: "CollationName") -> str:
+    def validate_collation_name(self, expr: "CollateExpression") -> str:
         """Validate SQL Server collation names and return their SQL representation."""
-        if collation.schema is not None:
+        if "schema" in expr.collation_options:
             raise UnsupportedFeatureError(self.name, "schema-qualified COLLATE")
-        if collation.keyword is not None and collation.keyword != "DATABASE_DEFAULT":
-            raise ValueError(f"Unsupported SQL Server collation keyword: {collation.keyword!r}")
-        return validate_sqlserver_collation_name(collation.keyword or collation.name, getattr(self, "version", None))
+        keyword = expr.collation_options.get("keyword", False)
+        unsupported = set(expr.collation_options) - {"keyword", "schema"}
+        if unsupported:
+            options = ", ".join(sorted(unsupported))
+            raise UnsupportedFeatureError(self.name, f"COLLATE options: {options}")
+        if keyword and expr.collation_name != "DATABASE_DEFAULT":
+            raise ValueError(f"Unsupported SQL Server collation keyword: {expr.collation_name!r}")
+        return validate_sqlserver_collation_name(expr.collation_name, getattr(self, "version", None))
 
     def format_identifier(self, identifier: str) -> str:
         """

tests/rhosocial/activerecord_sqlserver_test/feature/query/test_collation_expression.py

@@ -6,7 +6,6 @@
 import pytest
 
 from rhosocial.activerecord.backend.expression import Column, Literal
-from rhosocial.activerecord.backend.expression.collation import CollationName
 from rhosocial.activerecord.backend.impl.sqlserver import SQLServerCollation, SQLServerDialect
 
 
@@ -52,7 +51,7 @@ def test_literal_collate_preserves_parameter_binding(self, dialect):
         assert params == ("Alice",)
 
     def test_database_default_keyword_generates_sql(self, dialect):
-        expr = Column(dialect, "name").collate(CollationName.as_keyword("DATABASE_DEFAULT"))
+        expr = Column(dialect, "name").collate("DATABASE_DEFAULT", keyword=True)
 
         sql, params = expr.to_sql()
 
@@ -61,14 +60,14 @@ def test_database_default_keyword_generates_sql(self, dialect):
 
     def test_rejects_schema_qualified_collation(self, dialect):
         expr = Column(dialect, "name").collate(
-            CollationName(SQLServerCollation.LATIN1_GENERAL_CI_AS.value, schema="dbo")
+            SQLServerCollation.LATIN1_GENERAL_CI_AS.value, schema="dbo"
         )
 
         with pytest.raises(Exception, match="schema-qualified COLLATE"):
             expr.to_sql()
 
     def test_rejects_unsupported_keyword(self, dialect):
-        expr = Column(dialect, "name").collate(CollationName.as_keyword("CATALOG_DEFAULT"))
+        expr = Column(dialect, "name").collate("CATALOG_DEFAULT", keyword=True)
 
         with pytest.raises(ValueError, match="Unsupported SQL Server collation keyword"):
             expr.to_sql()