diff --git a/test/helpers/dom-helpers.ts b/test/helpers/dom-helpers.ts
new file mode 100644
index 0000000..e242f14
--- /dev/null
+++ b/test/helpers/dom-helpers.ts
@@ -0,0 +1,40 @@
+import { CalendarEvent } from '../../src/types/CalendarTypes';
+
+/**
+ * Setup mock DOM for testing
+ */
+export function setupMockDOM(): void {
+  // Create basic DOM structure for testing
+  document.body.innerHTML = `
+    <div class="swp-calendar-grid" data-current="true">
+      <div class="swp-day-header" data-date="2024-09-22"></div>
+      <div class="swp-day-header" data-date="2024-09-23"></div>
+      <div class="swp-day-header" data-date="2024-09-24"></div>
+      <div class="swp-day-header" data-date="2024-09-25"></div>
+      <div class="swp-day-header" data-date="2024-09-26"></div>
+    </div>
+    <swp-calendar-header>
+      <swp-allday-container></swp-allday-container>
+    </swp-calendar-header>
+  `;
+}
+
+/**
+ * Create mock CalendarEvent for testing
+ */
+export function createMockEvent(
+  id: string, 
+  title: string, 
+  startDate: string, 
+  endDate: string
+): CalendarEvent {
+  return {
+    id,
+    title,
+    start: new Date(startDate),
+    end: new Date(endDate),
+    type: 'work',
+    allDay: true,
+    syncStatus: 'synced'
+  };
+}
\ No newline at end of file
diff --git a/test/managers/AllDayManager.test.ts b/test/managers/AllDayManager.test.ts
index 83018fe..76c68ae 100644
--- a/test/managers/AllDayManager.test.ts
+++ b/test/managers/AllDayManager.test.ts
@@ -14,121 +14,130 @@ describe('AllDayManager - Layout Calculation', () => {
     it('Scenario 1: Non-overlapping single-day events', () => {
       // Event 1: Sept 22 (column 1)
       const event1 = createMockEvent('1', 'Event 1', '2024-09-22', '2024-09-22');
-      const layout1 = allDayManager.calculateAllDayEventLayout(event1);
-      
-      expect(layout1.startColumn).toBe(1);
-      expect(layout1.row).toBe(1);
-      
       // Event 2: Sept 24 (column 3) - different column, should be row 1
       const event2 = createMockEvent('2', 'Event 2', '2024-09-24', '2024-09-24');
-      const layout2 = allDayManager.calculateAllDayEventLayout(event2);
       
-      expect(layout2.startColumn).toBe(3);
-      expect(layout2.row).toBe(1);
+      // Test both events together using new batch method
+      const weekDates = ['2024-09-22', '2024-09-23', '2024-09-24', '2024-09-25', '2024-09-26'];
+      const layouts = allDayManager.calculateAllDayEventsLayout([event1, event2], weekDates);
+      
+      const layout1 = layouts.get('1');
+      const layout2 = layouts.get('2');
+      
+      expect(layout1?.startColumn).toBe(1);
+      expect(layout1?.row).toBe(1);
+      expect(layout2?.startColumn).toBe(3);
+      expect(layout2?.row).toBe(1);
     });
 
     it('Scenario 2: Overlapping multi-day events - Autumn Equinox vs Teknisk Workshop', () => {
       // Autumn Equinox: Sept 22-23 (columns 1-2)
       const autumnEvent = createMockEvent('autumn', 'Autumn Equinox', '2024-09-22', '2024-09-23');
-      const autumnLayout = allDayManager.calculateAllDayEventLayout(autumnEvent);
-      
-      expect(autumnLayout.startColumn).toBe(1);
-      expect(autumnLayout.endColumn).toBe(2);
-      expect(autumnLayout.row).toBe(1);
-      
       // Teknisk Workshop: Sept 23-26 (columns 2-5) - overlaps on Sept 23
       const workshopEvent = createMockEvent('workshop', 'Teknisk Workshop', '2024-09-23', '2024-09-26');
-      const workshopLayout = allDayManager.calculateAllDayEventLayout(workshopEvent);
       
-      expect(workshopLayout.startColumn).toBe(2);
-      expect(workshopLayout.endColumn).toBe(5);
-      expect(workshopLayout.row).toBe(2); // Should be row 2 due to overlap
+      const weekDates = ['2024-09-22', '2024-09-23', '2024-09-24', '2024-09-25', '2024-09-26'];
+      const layouts = allDayManager.calculateAllDayEventsLayout([autumnEvent, workshopEvent], weekDates);
+      
+      const autumnLayout = layouts.get('autumn');
+      const workshopLayout = layouts.get('workshop');
+      
+      // Workshop is longer (4 days) so gets row 1, Autumn gets row 2 due to longest-first sorting
+      expect(workshopLayout?.startColumn).toBe(2);
+      expect(workshopLayout?.endColumn).toBe(5);
+      expect(workshopLayout?.row).toBe(1); // Longest event gets row 1
+      expect(autumnLayout?.startColumn).toBe(1);
+      expect(autumnLayout?.endColumn).toBe(2);
+      expect(autumnLayout?.row).toBe(2); // Shorter overlapping event gets row 2
     });
 
     it('Scenario 3: Multiple events in same column', () => {
-      // Event 1: Sept 23 only
+      // All events on Sept 23 only
       const event1 = createMockEvent('1', 'Event 1', '2024-09-23', '2024-09-23');
-      const layout1 = allDayManager.calculateAllDayEventLayout(event1);
-      
-      expect(layout1.startColumn).toBe(2);
-      expect(layout1.row).toBe(1);
-      
-      // Event 2: Sept 23 only - same column, should be row 2
       const event2 = createMockEvent('2', 'Event 2', '2024-09-23', '2024-09-23');
-      const layout2 = allDayManager.calculateAllDayEventLayout(event2);
-      
-      expect(layout2.startColumn).toBe(2);
-      expect(layout2.row).toBe(2);
-      
-      // Event 3: Sept 23 only - same column, should be row 3
       const event3 = createMockEvent('3', 'Event 3', '2024-09-23', '2024-09-23');
-      const layout3 = allDayManager.calculateAllDayEventLayout(event3);
       
-      expect(layout3.startColumn).toBe(2);
-      expect(layout3.row).toBe(3);
+      const weekDates = ['2024-09-22', '2024-09-23', '2024-09-24', '2024-09-25', '2024-09-26'];
+      const layouts = allDayManager.calculateAllDayEventsLayout([event1, event2, event3], weekDates);
+      
+      const layout1 = layouts.get('1');
+      const layout2 = layouts.get('2');
+      const layout3 = layouts.get('3');
+      
+      expect(layout1?.startColumn).toBe(2);
+      expect(layout1?.row).toBe(1);
+      expect(layout2?.startColumn).toBe(2);
+      expect(layout2?.row).toBe(2);
+      expect(layout3?.startColumn).toBe(2);
+      expect(layout3?.row).toBe(3);
     });
 
     it('Scenario 4: Partial overlaps', () => {
       // Event 1: Sept 22-23 (columns 1-2)
       const event1 = createMockEvent('1', 'Event 1', '2024-09-22', '2024-09-23');
-      const layout1 = allDayManager.calculateAllDayEventLayout(event1);
-      
-      expect(layout1.startColumn).toBe(1);
-      expect(layout1.endColumn).toBe(2);
-      expect(layout1.row).toBe(1);
-      
       // Event 2: Sept 23-24 (columns 2-3) - overlaps on Sept 23
       const event2 = createMockEvent('2', 'Event 2', '2024-09-23', '2024-09-24');
-      const layout2 = allDayManager.calculateAllDayEventLayout(event2);
-      
-      expect(layout2.startColumn).toBe(2);
-      expect(layout2.endColumn).toBe(3);
-      expect(layout2.row).toBe(2); // Should be row 2 due to overlap
-      
       // Event 3: Sept 25-26 (columns 4-5) - no overlap, should be row 1
       const event3 = createMockEvent('3', 'Event 3', '2024-09-25', '2024-09-26');
-      const layout3 = allDayManager.calculateAllDayEventLayout(event3);
       
-      expect(layout3.startColumn).toBe(4);
-      expect(layout3.endColumn).toBe(5);
-      expect(layout3.row).toBe(1); // No overlap, back to row 1
+      const weekDates = ['2024-09-22', '2024-09-23', '2024-09-24', '2024-09-25', '2024-09-26'];
+      const layouts = allDayManager.calculateAllDayEventsLayout([event1, event2, event3], weekDates);
+      
+      const layout1 = layouts.get('1');
+      const layout2 = layouts.get('2');
+      const layout3 = layouts.get('3');
+      
+      expect(layout1?.startColumn).toBe(1);
+      expect(layout1?.endColumn).toBe(2);
+      expect(layout1?.row).toBe(1);
+      expect(layout2?.startColumn).toBe(2);
+      expect(layout2?.endColumn).toBe(3);
+      expect(layout2?.row).toBe(2); // Should be row 2 due to overlap
+      expect(layout3?.startColumn).toBe(4);
+      expect(layout3?.endColumn).toBe(5);
+      expect(layout3?.row).toBe(1); // No overlap, back to row 1
     });
 
     it('Scenario 5: Complex overlapping pattern', () => {
-      // Event 1: Sept 22-25 (columns 1-4) - spans most of week
+      // Event 1: Sept 22-25 (columns 1-4) - spans most of week (4 days)
       const event1 = createMockEvent('1', 'Long Event', '2024-09-22', '2024-09-25');
-      const layout1 = allDayManager.calculateAllDayEventLayout(event1);
-      
-      expect(layout1.startColumn).toBe(1);
-      expect(layout1.endColumn).toBe(4);
-      expect(layout1.row).toBe(1);
-      
-      // Event 2: Sept 23-24 (columns 2-3) - overlaps with Event 1
+      // Event 2: Sept 23-24 (columns 2-3) - overlaps with Event 1 (2 days)
       const event2 = createMockEvent('2', 'Short Event', '2024-09-23', '2024-09-24');
-      const layout2 = allDayManager.calculateAllDayEventLayout(event2);
-      
-      expect(layout2.startColumn).toBe(2);
-      expect(layout2.endColumn).toBe(3);
-      expect(layout2.row).toBe(2);
-      
-      // Event 3: Sept 24-26 (columns 3-5) - overlaps with both
+      // Event 3: Sept 24-26 (columns 3-5) - overlaps with both (3 days)
       const event3 = createMockEvent('3', 'Another Event', '2024-09-24', '2024-09-26');
-      const layout3 = allDayManager.calculateAllDayEventLayout(event3);
       
-      expect(layout3.startColumn).toBe(3);
-      expect(layout3.endColumn).toBe(5);
-      expect(layout3.row).toBe(3); // Should be row 3 due to overlaps with both
+      const weekDates = ['2024-09-22', '2024-09-23', '2024-09-24', '2024-09-25', '2024-09-26'];
+      const layouts = allDayManager.calculateAllDayEventsLayout([event1, event2, event3], weekDates);
+      
+      const layout1 = layouts.get('1');
+      const layout2 = layouts.get('2');
+      const layout3 = layouts.get('3');
+      
+      // Longest-first sorting: Event1 (4 days) -> Event3 (3 days) -> Event2 (2 days)
+      expect(layout1?.startColumn).toBe(1);
+      expect(layout1?.endColumn).toBe(4);
+      expect(layout1?.row).toBe(1); // Longest event gets row 1
+      expect(layout3?.startColumn).toBe(3);
+      expect(layout3?.endColumn).toBe(5);
+      expect(layout3?.row).toBe(2); // Second longest, overlaps with Event1, gets row 2
+      expect(layout2?.startColumn).toBe(2);
+      expect(layout2?.endColumn).toBe(3);
+      expect(layout2?.row).toBe(3); // Shortest, overlaps with both, gets row 3
     });
 
-    it('Scenario 6: Drag-drop target date override', () => {
-      // Multi-day event dragged to specific date should use single column
-      const event = createMockEvent('drag', 'Dragged Event', '2024-09-22', '2024-09-25');
-      const layout = allDayManager.calculateAllDayEventLayout(event, '2024-09-24');
+    it('Scenario 6: Single event for drag-drop simulation', () => {
+      // Single event placed at specific date
+      const event = createMockEvent('drag', 'Dragged Event', '2024-09-24', '2024-09-24');
       
-      expect(layout.startColumn).toBe(3); // Sept 24 is column 3
-      expect(layout.endColumn).toBe(3);   // Single column when targetDate specified
-      expect(layout.columnSpan).toBe(1);
-      expect(layout.row).toBe(1);
+      const weekDates = ['2024-09-22', '2024-09-23', '2024-09-24', '2024-09-25', '2024-09-26'];
+      const layouts = allDayManager.calculateAllDayEventsLayout([event], weekDates);
+      
+      const layout = layouts.get('drag');
+      
+      expect(layout?.startColumn).toBe(3); // Sept 24 is column 3
+      expect(layout?.endColumn).toBe(3);   // Single column
+      expect(layout?.columnSpan).toBe(1);
+      expect(layout?.row).toBe(1);
     });
   });
 });
\ No newline at end of file