fix issue

apps/edr-freight-api/src/modules/trains/train-builder.reorder.spec.ts

@@ -0,0 +1,44 @@
+import { orderSlotsByWagonSequence } from './train-builder.service';
+
+describe('orderSlotsByWagonSequence', () => {
+  const slot = (sequenceNo: number, physicalWagonId: string | null) => ({
+    sequenceNo,
+    physicalWagonId,
+  });
+
+  it('reorders pinned slots to the wagons’ new positions, unpinned trail in old order', () => {
+    // Built train reordered to w3, w1, w2. Slots 1..5: three pinned + two empty.
+    const newSeq = new Map([
+      ['w3', 1],
+      ['w1', 2],
+      ['w2', 3],
+    ]);
+    const slots = [
+      slot(1, 'w1'),
+      slot(2, 'w2'),
+      slot(3, 'w3'),
+      slot(4, null),
+      slot(5, null),
+    ];
+    expect(orderSlotsByWagonSequence(slots, newSeq).map((s) => s.physicalWagonId)).toEqual([
+      'w3',
+      'w1',
+      'w2',
+      null,
+      null,
+    ]);
+    // Unpinned keep their old relative order (4 before 5).
+    expect(orderSlotsByWagonSequence(slots, newSeq).map((s) => s.sequenceNo)).toEqual([
+      3, 1, 2, 4, 5,
+    ]);
+  });
+
+  it('slots pinned to wagons outside the reorder trail like unpinned ones', () => {
+    const newSeq = new Map([['w2', 1]]);
+    const slots = [slot(1, 'w-foreign'), slot(2, 'w2')];
+    expect(orderSlotsByWagonSequence(slots, newSeq).map((s) => s.physicalWagonId)).toEqual([
+      'w2',
+      'w-foreign',
+    ]);
+  });
+});