diff --git a/app/src/test/java/org/mozilla/fenix/ext/BookmarkNodeTest.kt b/app/src/test/java/org/mozilla/fenix/ext/BookmarkNodeTest.kt
new file mode 100644
index 000000000..99f967ff4
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+++ b/app/src/test/java/org/mozilla/fenix/ext/BookmarkNodeTest.kt
@@ -0,0 +1,110 @@
+/* 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/. */
+
+package org.mozilla.fenix.ext
+
+import org.junit.Assert.assertEquals
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.mozilla.fenix.TestApplication
+import org.robolectric.RobolectricTestRunner
+import org.robolectric.annotation.Config
+import mozilla.components.concept.storage.BookmarkNode
+import mozilla.components.concept.storage.BookmarkNodeType
+
+@RunWith(RobolectricTestRunner::class)
+@Config(application = TestApplication::class)
+class BookmarkNodeTest {
+
+    @Test
+    fun `GIVEN a bookmark node with children WHEN minusing a sub set of children THEN the children subset is removed and rest remains`() {
+        val bookMarkChild1 = newBookmarkNode("Child 1", 1, null)
+        val bookMarkChild2 = newBookmarkNode("Child 2", 2, null)
+        val allChildren = listOf(bookMarkChild1, bookMarkChild2)
+        val bookmarkNode = newBookmarkNode("Parent 1", 0, allChildren)
+        val subsetToSubtract = setOf(bookMarkChild1)
+        val expectedRemainingSubset = listOf(bookMarkChild2)
+        val bookmarkNodeSubsetRemoved = bookmarkNode.minus(subsetToSubtract)
+        assertEquals(expectedRemainingSubset, bookmarkNodeSubsetRemoved.children)
+    }
+
+    @Test
+    fun `GIVEN a bookmark node with children WHEN minusing a set of all children THEN all children are removed and empty list remains`() {
+        val bookMarkChild1 = newBookmarkNode("Child 1", 1, null)
+        val bookMarkChild2 = newBookmarkNode("Child 2", 2, null)
+        val allChildren = listOf(bookMarkChild1, bookMarkChild2)
+        val bookmarkNode = newBookmarkNode("Parent 1", 0, allChildren)
+        val setofAllChildren = setOf(bookMarkChild1, bookMarkChild2)
+        val bookmarkNodeAllChildrenRemoved = bookmarkNode.minus(setofAllChildren)
+        assertEquals(emptyList<BookmarkNode>(), bookmarkNodeAllChildrenRemoved.children)
+    }
+
+    @Test
+    fun `GIVEN a bookmark node with children WHEN minusing a set of non-children THEN no children are removed`() {
+        val bookMarkChild1 = newBookmarkNode("Child 1", 1, null)
+        val bookMarkChild2 = newBookmarkNode("Child 2", 2, null)
+        val allChildren = listOf(bookMarkChild1, bookMarkChild2)
+        val bookMarkChild3 = newBookmarkNode("Child 3", 3, null)
+        val setofNonChildren = setOf(bookMarkChild3)
+        val bookmarkNode = newBookmarkNode("Parent 1", 0, allChildren)
+        val bookmarkNodeNonChildrenRemoved = bookmarkNode.minus(setofNonChildren)
+        assertEquals(allChildren, bookmarkNodeNonChildrenRemoved.children)
+    }
+
+    @Test
+    fun `GIVEN a bookmark node with children WHEN minusing an empty set THEN no children are removed`() {
+        val bookMarkChild1 = newBookmarkNode("Child 1", 1, null)
+        val bookMarkChild2 = newBookmarkNode("Child 2", 2, null)
+        val allChildren = listOf(bookMarkChild1, bookMarkChild2)
+        val bookmarkNode = newBookmarkNode("Parent 1", 0, allChildren)
+        val bookmarkNodeEmptySetRemoved = bookmarkNode.minus(emptySet())
+        assertEquals(allChildren, bookmarkNodeEmptySetRemoved.children)
+    }
+
+    @Test
+    fun `GIVEN a bookmark node with an empty list as children WHEN minusing a set of non-children from an empty parent THEN an empty list remains`() {
+        val parentWithEmptyList = newBookmarkNode("Parent 1", 0, emptyList<BookmarkNode>())
+        val bookMarkChild1 = newBookmarkNode("Child 1", 1, null)
+        val bookMarkChild2 = newBookmarkNode("Child 2", 2, null)
+        val setofAllChildren = setOf(bookMarkChild1, bookMarkChild2)
+        val parentWithEmptyListNonChildRemoved = parentWithEmptyList.minus(setofAllChildren)
+        assertEquals(emptyList<BookmarkNode>(), parentWithEmptyListNonChildRemoved.children)
+    }
+
+    @Test
+    fun `GIVEN a bookmark node with null as children WHEN minusing a set of non-children from a parent with null children THEN null remains`() {
+        val parentWithNullList = newBookmarkNode("Parent 1", 0, null)
+        val bookMarkChild1 = newBookmarkNode("Child 1", 1, null)
+        val bookMarkChild2 = newBookmarkNode("Child 2", 2, null)
+        val setofAllChildren = setOf(bookMarkChild1, bookMarkChild2)
+        val parentWithNullListNonChildRemoved = parentWithNullList.minus(setofAllChildren)
+        assertEquals(null, parentWithNullListNonChildRemoved.children)
+    }
+
+    @Test
+    fun `GIVEN a bookmark node with children WHEN minusing a sub-set of children THEN the rest of the parents object should remain the same`() {
+        val bookMarkChild1 = newBookmarkNode("Child 1", 1, null)
+        val bookMarkChild2 = newBookmarkNode("Child 2", 2, null)
+        val allChildren = listOf(bookMarkChild1, bookMarkChild2)
+        val bookmarkNode = newBookmarkNode("Parent 1", 0, allChildren)
+        val subsetToSubtract = setOf(bookMarkChild1)
+        val expectedRemainingSubset = listOf(bookMarkChild2)
+        val resultBookmarkNode = bookmarkNode.minus(subsetToSubtract)
+
+        // We're pinning children to the same value so we can compare the rest.
+        val restOfResult = resultBookmarkNode.copy(children = expectedRemainingSubset)
+        val restofOriginal = bookmarkNode.copy(children = expectedRemainingSubset)
+        assertEquals(restOfResult, restofOriginal)
+    }
+
+    private fun newBookmarkNode(title: String, position: Int, children: List<BookmarkNode>?) = BookmarkNode(
+            type = BookmarkNodeType.ITEM,
+            guid = "11",
+            parentGuid = "12",
+            position = position,
+            title = title,
+            url = "www.mockurl.com",
+            children = children
+    )
+}