From 60b4a58bc3279414638c59dc01717777510929be Mon Sep 17 00:00:00 2001
From: Kristiyan Kostadinov <crisbeto@users.noreply.github.com>
Date: Mon, 15 Oct 2018 23:15:45 +0300
Subject: [PATCH] fix(drag-drop): enterPredicate being called with wrong drop
 container (#13578)

Fixes the `enterPredicate` being called with the item's current container, rather than the one it is being moved into. Also tweaks the function signature to avoid unnecessary null checks and expands the description.
---
 src/cdk/drag-drop/drag.spec.ts | 22 ++++++++++++++++++++++
 src/cdk/drag-drop/drop.ts      |  9 +++++----
 2 files changed, 27 insertions(+), 4 deletions(-)

diff --git a/src/cdk/drag-drop/drag.spec.ts b/src/cdk/drag-drop/drag.spec.ts
index 2b3ba46a4f5..f5fc896195c 100644
--- a/src/cdk/drag-drop/drag.spec.ts
+++ b/src/cdk/drag-drop/drag.spec.ts
@@ -1437,6 +1437,28 @@ describe('CdkDrag', () => {
         });
       }));
 
+    it('should call the `enterPredicate` with the item and the container it is entering',
+      fakeAsync(() => {
+        const fixture = createComponent(ConnectedDropZones);
+        fixture.detectChanges();
+
+        const dropInstances = fixture.componentInstance.dropInstances.toArray();
+        const spy = jasmine.createSpy('enterPredicate spy').and.returnValue(true);
+        const groups = fixture.componentInstance.groupedDragItems.slice();
+        const dragItem = groups[0][1];
+        const targetRect = groups[1][2].element.nativeElement.getBoundingClientRect();
+
+        dropInstances[1].enterPredicate = spy;
+        fixture.detectChanges();
+
+        dragElementViaMouse(fixture, dragItem.element.nativeElement,
+              targetRect.left + 1, targetRect.top + 1);
+        flush();
+        fixture.detectChanges();
+
+        expect(spy).toHaveBeenCalledWith(dragItem, dropInstances[1]);
+      }));
+
     it('should be able to start dragging after an item has been transferred', fakeAsync(() => {
       const fixture = createComponent(ConnectedDropZones);
       fixture.detectChanges();
diff --git a/src/cdk/drag-drop/drop.ts b/src/cdk/drag-drop/drop.ts
index 1a2e3eeb726..d70b9c3b108 100644
--- a/src/cdk/drag-drop/drop.ts
+++ b/src/cdk/drag-drop/drop.ts
@@ -77,11 +77,12 @@ export class CdkDrop<T = any> implements OnInit, OnDestroy {
   @Input('cdkDropLockAxis') lockAxis: 'x' | 'y';
 
   /**
-   * Function that is used to determine whether an item
-   * is allowed to be moved into a drop container.
+   * Function that is used to determine whether an item is allowed to be moved
+   * into a drop container. The function will be called with the item that is
+   * being dragged and the container that it's being moved into.
    */
   @Input('cdkDropEnterPredicate')
-  enterPredicate: (drag?: CdkDrag, drop?: CdkDrop) => boolean = () => true
+  enterPredicate: (drag: CdkDrag, drop: CdkDrop) => boolean = () => true
 
   /** Emits when the user drops an item inside the container. */
   @Output('cdkDropDropped')
@@ -315,7 +316,7 @@ export class CdkDrop<T = any> implements OnInit, OnDestroy {
     const result = this._positionCache.siblings
         .find(sibling => isInsideClientRect(sibling.clientRect, x, y));
 
-    return result && result.drop.enterPredicate(item, this) ? result.drop : null;
+    return result && result.drop.enterPredicate(item, result.drop) ? result.drop : null;
   }
 
   /**