No issue: add some BookmarkFragmentInteractor tests

app/src/main/java/org/mozilla/fenix/library/bookmarks/BookmarkFragmentInteractor.kt

@@ -140,10 +140,13 @@ class BookmarkFragmentInteractor(
     }
 
     override fun delete(nodes: Set<BookmarkNode>) {
+        if (nodes.find { it.type == BookmarkNodeType.SEPARATOR } != null) {
+            throw IllegalStateException("Cannot delete separators")
+        }
         val eventType = when (nodes.singleOrNull()?.type) {
-            BookmarkNodeType.ITEM -> Event.RemoveBookmark
+            BookmarkNodeType.ITEM,
+            BookmarkNodeType.SEPARATOR -> Event.RemoveBookmark
             BookmarkNodeType.FOLDER -> Event.RemoveBookmarkFolder
-            BookmarkNodeType.SEPARATOR -> throw IllegalStateException("Cannot delete separators")
             null -> Event.RemoveBookmarks
         }
         deleteBookmarkNodes(nodes, eventType)

app/src/test/java/org/mozilla/fenix/library/bookmarks/BookmarkFragmentInteractorTest.kt

@@ -115,6 +115,11 @@ class BookmarkFragmentInteractorTest {
         metrics.track(Event.OpenedBookmark)
     }
 
+    @Test(expected = IllegalStateException::class)
+    fun `open a separator`() {
+        interactor.open(item.copy(type = BookmarkNodeType.SEPARATOR))
+    }
+
     @Test
     fun `expand a level of bookmarks`() {
         interactor.open(tree)
@@ -243,6 +248,11 @@ class BookmarkFragmentInteractorTest {
         }
     }
 
+    @Test(expected = IllegalStateException::class)
+    fun `delete a separator`() {
+        interactor.delete(setOf(item, item.copy(type = BookmarkNodeType.SEPARATOR)))
+    }
+
     @Test
     fun `delete a bookmark folder`() {
         interactor.delete(setOf(subfolder))