def testProxyFeatureSink(self):
        fields = QgsFields()
        fields.append(QgsField('fldtxt', QVariant.String))
        fields.append(QgsField('fldint', QVariant.Int))

        store = QgsFeatureStore(fields, QgsCoordinateReferenceSystem())
        proxy = QgsProxyFeatureSink(store)
        self.assertEqual(proxy.destinationSink(), store)

        self.assertEqual(len(store), 0)

        f = QgsFeature()
        f.setAttributes(["test", 123])
        f.setGeometry(QgsGeometry.fromPointXY(QgsPointXY(100, 200)))
        proxy.addFeature(f)
        self.assertEqual(len(store), 1)
        self.assertEqual(store.features()[0]['fldtxt'], 'test')

        f2 = QgsFeature()
        f2.setAttributes(["test2", 457])
        f2.setGeometry(QgsGeometry.fromPointXY(QgsPointXY(200, 200)))
        f3 = QgsFeature()
        f3.setAttributes(["test3", 888])
        f3.setGeometry(QgsGeometry.fromPointXY(QgsPointXY(300, 200)))
        proxy.addFeatures([f2, f3])
        self.assertEqual(len(store), 3)
        self.assertEqual(store.features()[1]['fldtxt'], 'test2')
        self.assertEqual(store.features()[2]['fldtxt'], 'test3')

    def testFromIterator(self):
        """
        Test adding features from an iterator
        :return:
        """
        layer = createLayerWithFivePoints()
        store = QgsFeatureStore(layer.fields(), layer.crs())

        self.assertTrue(store.addFeatures(layer.getFeatures()))
        vals = [f['fldint'] for f in store.features()]
        self.assertEqual(vals, [123, 457, 888, -1, 0])