diff -r 000000000000 -r 6474c204b198 toolkit/modules/tests/browser/browser_Geometry.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toolkit/modules/tests/browser/browser_Geometry.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,111 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+let tempScope = {};
+Components.utils.import("resource://gre/modules/Geometry.jsm", tempScope);
+let Point = tempScope.Point;
+let Rect = tempScope.Rect;
+
+function test() {
+  ok(Rect, "Rect class exists");
+  for (var fname in tests) {
+    tests[fname]();
+  }
+}
+
+let tests = {
+  testGetDimensions: function() {
+    let r = new Rect(5, 10, 100, 50);
+    ok(r.left == 5, "rect has correct left value");
+    ok(r.top == 10, "rect has correct top value");
+    ok(r.right == 105, "rect has correct right value");
+    ok(r.bottom == 60, "rect has correct bottom value");
+    ok(r.width == 100, "rect has correct width value");
+    ok(r.height == 50, "rect has correct height value");
+    ok(r.x == 5, "rect has correct x value");
+    ok(r.y == 10, "rect has correct y value");
+  },
+
+  testIsEmpty: function() {
+    let r = new Rect(0, 0, 0, 10);
+    ok(r.isEmpty(), "rect with nonpositive width is empty");
+    let r = new Rect(0, 0, 10, 0);
+    ok(r.isEmpty(), "rect with nonpositive height is empty");
+    let r = new Rect(0, 0, 10, 10);
+    ok(!r.isEmpty(), "rect with positive dimensions is not empty");
+  },
+
+  testRestrictTo: function() {
+    let r1 = new Rect(10, 10, 100, 100);
+    let r2 = new Rect(50, 50, 100, 100);
+    r1.restrictTo(r2);
+    ok(r1.equals(new Rect(50, 50, 60, 60)), "intersection is non-empty");
+
+    let r1 = new Rect(10, 10, 100, 100);
+    let r2 = new Rect(120, 120, 100, 100);
+    r1.restrictTo(r2);
+    ok(r1.isEmpty(), "intersection is empty");
+
+    let r1 = new Rect(10, 10, 100, 100);
+    let r2 = new Rect(0, 0, 0, 0);
+    r1.restrictTo(r2);
+    ok(r1.isEmpty(), "intersection of rect and empty is empty");
+
+    let r1 = new Rect(0, 0, 0, 0);
+    let r2 = new Rect(0, 0, 0, 0);
+    r1.restrictTo(r2);
+    ok(r1.isEmpty(), "intersection of empty and empty is empty");
+  },
+
+  testExpandToContain: function() {
+    let r1 = new Rect(10, 10, 100, 100);
+    let r2 = new Rect(50, 50, 100, 100);
+    r1.expandToContain(r2);
+    ok(r1.equals(new Rect(10, 10, 140, 140)), "correct expandToContain on intersecting rectangles");
+
+    let r1 = new Rect(10, 10, 100, 100);
+    let r2 = new Rect(120, 120, 100, 100);
+    r1.expandToContain(r2);
+    ok(r1.equals(new Rect(10, 10, 210, 210)), "correct expandToContain on non-intersecting rectangles");
+
+    let r1 = new Rect(10, 10, 100, 100);
+    let r2 = new Rect(0, 0, 0, 0);
+    r1.expandToContain(r2);
+    ok(r1.equals(new Rect(10, 10, 100, 100)), "expandToContain of rect and empty is rect");
+
+    let r1 = new Rect(10, 10, 0, 0);
+    let r2 = new Rect(0, 0, 0, 0);
+    r1.expandToContain(r2);
+    ok(r1.isEmpty(), "expandToContain of empty and empty is empty");
+  },
+
+  testSubtract: function testSubtract() {
+    function equals(rects1, rects2) {
+      return rects1.length == rects2.length && rects1.every(function(r, i) {
+        return r.equals(rects2[i]);
+      });
+    }
+
+    let r1 = new Rect(0, 0, 100, 100);
+    let r2 = new Rect(500, 500, 100, 100);
+    ok(equals(r1.subtract(r2), [r1]), "subtract area outside of region yields same region");
+
+    let r1 = new Rect(0, 0, 100, 100);
+    let r2 = new Rect(-10, -10, 50, 120);
+    ok(equals(r1.subtract(r2), [new Rect(40, 0, 60, 100)]), "subtracting vertical bar from edge leaves one rect");
+
+    let r1 = new Rect(0, 0, 100, 100);
+    let r2 = new Rect(-10, -10, 120, 50);
+    ok(equals(r1.subtract(r2), [new Rect(0, 40, 100, 60)]), "subtracting horizontal bar from edge leaves one rect");
+
+    let r1 = new Rect(0, 0, 100, 100);
+    let r2 = new Rect(40, 40, 20, 20);
+    ok(equals(r1.subtract(r2), [
+      new Rect(0, 0, 40, 100),
+      new Rect(40, 0, 20, 40),
+      new Rect(40, 60, 20, 40),
+      new Rect(60, 0, 40, 100)]),
+      "subtracting rect in middle leaves union of rects");
+  },
+};