fix issue

apps/edr-freight-api/src/modules/train-scheduling/container-placement.util.spec.ts

@@ -1,6 +1,7 @@
 import {
   autoFillPlacements,
   findMissingContainerNumberIssues,
+  occupiedTeuPerEdgeBySlot,
   type ContainerUnitForPlacement,
 } from './container-placement.util';
 
@@ -27,14 +28,15 @@ describe('container-placement.util', () => {
   ];
 
   it('auto-fills placements across slots', () => {
-    const placements = autoFillPlacements(units, [1, 2]);
+    const { placements, overflow } = autoFillPlacements(units, [1, 2]);
     expect(placements).toHaveLength(2);
+    expect(overflow).toHaveLength(0);
     expect(placements[0].sequenceNo).toBe(1);
     expect(placements[1].sequenceNo).toBe(2);
   });
 
   it('reports missing container numbers only when placement is empty', () => {
-    const placements = autoFillPlacements(units, [1, 2]);
+    const { placements } = autoFillPlacements(units, [1, 2]);
     const issues = findMissingContainerNumberIssues(units, placements);
     expect(issues).toHaveLength(0);
     expect(placements[1].containerNumber).toMatch(/^TBD-/);
@@ -53,7 +55,84 @@ describe('container-placement.util', () => {
         containerNumber: null,
       },
     ];
-    const placements = autoFillPlacements(single, [1]);
+    const { placements } = autoFillPlacements(single, [1]);
     expect(placements[0].containerNumber).toBe('TBD-BK-2026-000033-1');
   });
+
+  const ft40 = (
+    bookingId: string,
+    i: number,
+    leg?: { from: number; to: number },
+  ): ContainerUnitForPlacement => ({
+    bookingId,
+    bookingReference: bookingId,
+    bookingContainerId: `${bookingId}-line`,
+    unitIndex: i,
+    label: `${bookingId} · ${i + 1} · 40GP`,
+    teuSlots: 2,
+    sizeFt: 40,
+    containerNumber: `CNT${bookingId}${i}`,
+    leg,
+  });
+
+  it('never clamps overflow onto the last slot — returns it instead', () => {
+    // 3 × 40ft, 2 slots. The old walk piled unit 3 onto slot #2 and let the
+    // validator reject it once per container ("Wagon #42…", the reported bug).
+    const three = [ft40('A', 0), ft40('A', 1), ft40('A', 2)];
+    const { placements, overflow } = autoFillPlacements(three, [1, 2]);
+    expect(placements).toHaveLength(2);
+    expect(overflow).toHaveLength(1);
+    expect(placements.every((p) => p.sequenceNo === 1 || p.sequenceNo === 2)).toBe(true);
+  });
+
+  it('leg-aware: disjoint-leg 40fts share one wagon (the staging case)', () => {
+    // 2 slots riding the whole 2-edge route. Leg-blind fill fits only two of
+    // these four 40fts; per-edge TEU fits all four — two per wagon, one per leg.
+    const slots = [
+      { sequenceNo: 1, from: 0, to: 2 },
+      { sequenceNo: 2, from: 0, to: 2 },
+    ];
+    const four = [
+      ft40('LEG1', 0, { from: 0, to: 1 }),
+      ft40('LEG1', 1, { from: 0, to: 1 }),
+      ft40('LEG2', 0, { from: 1, to: 2 }),
+      ft40('LEG2', 1, { from: 1, to: 2 }),
+    ];
+    const { placements, overflow } = autoFillPlacements(four, slots, new Map(), 2);
+    expect(overflow).toHaveLength(0);
+    expect(placements).toHaveLength(4);
+  });
+
+  it('same-leg 40fts still never share a wagon', () => {
+    const slots = [{ sequenceNo: 1, from: 0, to: 2 }];
+    const two = [ft40('X', 0, { from: 0, to: 1 }), ft40('X', 1, { from: 0, to: 1 })];
+    const { placements, overflow } = autoFillPlacements(two, slots, new Map(), 2);
+    expect(placements).toHaveLength(1);
+    expect(overflow).toHaveLength(1);
+  });
+
+  it('respects per-edge occupied TEU from caller-provided placements', () => {
+    const slots = [{ sequenceNo: 1, from: 0, to: 2 }];
+    const provided = [{ bookingContainerId: 'P-line', unitIndex: 0, sequenceNo: 1 }];
+    const providedUnit = ft40('P', 0, { from: 0, to: 1 });
+    const occupied = occupiedTeuPerEdgeBySlot(provided, [providedUnit], 2);
+    // Edge 0 is full on slot 1; an edge-0 unit overflows, an edge-1 unit fits.
+    const edge0 = autoFillPlacements([ft40('Q', 0, { from: 0, to: 1 })], slots, occupied, 2);
+    expect(edge0.overflow).toHaveLength(1);
+    const edge1 = autoFillPlacements([ft40('Q', 0, { from: 1, to: 2 })], slots, occupied, 2);
+    expect(edge1.overflow).toHaveLength(0);
+    expect(edge1.placements[0].sequenceNo).toBe(1);
+  });
+
+  it('a unit never lands on a slot that does not ride its leg', () => {
+    const slots = [{ sequenceNo: 1, from: 0, to: 1 }]; // alights at stop 1
+    const { placements, overflow } = autoFillPlacements(
+      [ft40('Y', 0, { from: 1, to: 2 })],
+      slots,
+      new Map(),
+      2,
+    );
+    expect(placements).toHaveLength(0);
+    expect(overflow).toHaveLength(1);
+  });
 });