From c45b6b63ddd19c01d03183ba8a336da952f07538 Mon Sep 17 00:00:00 2001
From: Benjamin Dobell <benjamin.dobell+git@glassechidna.com.au>
Date: Tue, 9 Jul 2019 22:09:00 +1000
Subject: [PATCH] fix: reference object popper positioning (closes #800)

---
 .../src/utils/findCommonOffsetParent.js       | 19 +++++---
 packages/popper/tests/functional/core.js      | 43 +++++++++++++++++++
 2 files changed, 56 insertions(+), 6 deletions(-)

diff --git a/packages/popper/src/utils/findCommonOffsetParent.js b/packages/popper/src/utils/findCommonOffsetParent.js
index ca905fab24..eac1da064e 100644
--- a/packages/popper/src/utils/findCommonOffsetParent.js
+++ b/packages/popper/src/utils/findCommonOffsetParent.js
@@ -1,19 +1,26 @@
 import isOffsetContainer from './isOffsetContainer';
 import getRoot from './getRoot';
 import getOffsetParent from './getOffsetParent';
+import getParentNode from './getParentNode';
 
 /**
- * Finds the offset parent common to the two provided nodes
+ * Finds the offset parent common to the two provided nodes/references
  * @method
  * @memberof Popper.Utils
- * @argument {Element} element1
- * @argument {Element} element2
+ * @argument {Element|Object} element1
+ * @argument {Element|Object} element2
  * @returns {Element} common offset parent
  */
 export default function findCommonOffsetParent(element1, element2) {
-  // This check is needed to avoid errors in case one of the elements isn't defined for any reason
-  if (!element1 || !element1.nodeType || !element2 || !element2.nodeType) {
-    return document.documentElement;
+  // This is needed in case one of the elements isn't defined or if one of the "elements" is a reference object.
+  if (!element2 || !element2.nodeType) {
+    if (element1 && element1.nodeType) {
+      element2 = getParentNode(element1);
+    } else {
+      return document.documentElement;
+    }
+  } else if (!element1 || !element1.nodeType) {
+    element1 = getParentNode(element2);
   }
 
   // Here we make sure to give as "start" the element that comes first in the DOM
diff --git a/packages/popper/tests/functional/core.js b/packages/popper/tests/functional/core.js
index cb9b96bf47..a9311285ae 100644
--- a/packages/popper/tests/functional/core.js
+++ b/packages/popper/tests/functional/core.js
@@ -1428,6 +1428,49 @@ const arrowSize = 5;
       });
     });
 
+    it('uses an object instead of the reference element to position its popper in a container', done => {
+      // As above
+      if (isIE10) {
+        pending();
+      }
+
+      jasmineWrapper.innerHTML = `
+        <div style="position: absolute; left: 10px; top: 10px; right: 10px; bottom: 10px;">
+          <div id="popper" style="background: purple;">popper</div>
+        </div>
+      `;
+
+      const popper = document.getElementById('popper');
+
+      const reference = {
+        getBoundingClientRect() {
+          return {
+            top: 10,
+            left: 100,
+            right: 150,
+            bottom: 90,
+            width: 50,
+            height: 80,
+          };
+        },
+        clientWidth: 50,
+        clientHeight: 80,
+      };
+
+      new Popper(reference, popper, {
+        placement: 'bottom-start',
+        onCreate() {
+          expect(getRect(popper).top).toBe(
+            reference.getBoundingClientRect().bottom
+          );
+          expect(getRect(popper).left).toBe(
+            reference.getBoundingClientRect().left
+          );
+          done();
+        },
+      });
+    });
+
     it('checks cases where the reference element is fixed', done => {
       jasmineWrapper.innerHTML = `
             <div id="reference" style="position: fixed; top: 100px; left: 100px; background: pink">reference</div>