test_in_blender.py

import unittest
import os
import bpy

class TestAddon(unittest.TestCase):
    def test_addon_enabled(self):
        self.assertIsNotNone(bpy.ops.import_scene.x)

    def test_import(self):
        filepath = os.path.dirname(__file__) + '\\models\\test.x'
        result = bpy.ops.import_scene.x(filepath=filepath)
        self.assertSetEqual(result, {'FINISHED'})

suite = unittest.defaultTestLoader.loadTestsFromTestCase(TestAddon)
unittest.TextTestRunner().run(suite)