Fix importing files and add a basic test

Still need to make the progress indicator work again. Also there may be
some performance to be gained by pooling item saves into a transaction
if one is already open.

test/tests/fileInterfaceTest.js

@@ -0,0 +1,40 @@
+describe("Zotero_File_Interface", function() {
+    let win;
+    before(function* () {
+        win = yield loadBrowserWindow();
+        yield OS.File.copy(OS.Path.join(getTestDataDirectory().path, "Test Import Translator.js"),
+                           OS.Path.join(Zotero.getTranslatorsDirectory().path, "Test Import Translator.js"));
+        yield Zotero.Translators.reinit();
+    });
+    after(function () {
+        win.close();
+    });
+
+    it('should import a file into a collection', function* () {
+        let testFile = getTestDataDirectory();
+        testFile.append("allTypesAndFields.js");
+        yield win.Zotero_File_Interface.importFile(testFile);
+
+        let importedCollection = yield Zotero.Collections.getByLibrary(Zotero.Libraries.userLibraryID).filter(x => x.name == 'allTypesAndFields');
+        assert.equal(importedCollection.length, 1);
+        let childItems = importedCollection[0].getChildItems();
+        let savedItems = {};
+        for (let i=0; i<childItems.length; i++) {
+            let savedItem = yield childItems[i].toJSON();
+            delete savedItem.dateAdded;
+            delete savedItem.dateModified;
+            delete savedItem.key;
+            delete savedItem.collections;
+            savedItems[Zotero.ItemTypes.getName(childItems[i].itemTypeID)] = savedItem;
+        }
+        let trueItems = loadSampleData('itemJSON');
+        for (let itemType in trueItems) {
+            let trueItem = trueItems[itemType];
+            delete trueItem.dateAdded;
+            delete trueItem.dateModified;
+            delete trueItem.key;
+            delete trueItem.collections;
+        }
+        assert.deepEqual(savedItems, trueItems, "saved items match inputs")
+    });
+});