test(query): accept cursor metadata in offset fixture

Author: KyleAMathews

packages/query-db-collection/tests/cursor-pagination.integration.test.ts

@@ -23,7 +23,8 @@ import type { Row, Scope } from './cursor-pagination/model.js'
  * cancellation, replacement, and cache reuse.
  *
  * The fixture endpoint supports prefix and rank-equality tie requests. Other
- * predicates and cursor expressions reject rather than silently dropping IR.
+ * predicates reject rather than silently dropping IR. The fixture validates
+ * cursor expressions, then chooses the explicit offset for its local reader.
  * Each tie filter has its own opaque backend sequence, just like the prefix.
  */
 function createFixture(
@@ -97,10 +98,24 @@ function createFixture(
           }
           reader = tie
         }
-        expect(
-          options?.cursor,
-          `fixture uses offset requests, not IR cursors`,
-        ).toBeUndefined()
+        if (options?.cursor) {
+          expect(options.cursor.whereCurrent).toMatchObject({
+            type: `func`,
+            name: `eq`,
+            args: [
+              { type: `ref`, path: [`rank`] },
+              { type: `val`, value: expect.any(Number) },
+            ],
+          })
+          expect(options.cursor.whereFrom).toMatchObject({
+            type: `func`,
+            name: scope.descending ? `lt` : `gt`,
+            args: [
+              { type: `ref`, path: [`rank`] },
+              { type: `val`, value: expect.any(Number) },
+            ],
+          })
+        }
         if (options?.orderBy) {
           expect(options.orderBy).toMatchObject([
             { expression: { path: [`rank`] }, compareOptions: { direction } },