Add rudimentary pytests

tests/test_client.py

@@ -0,0 +1,19 @@
+from opendrop.client import AirDropBrowser
+from opendrop.config import AirDropConfig
+
+
+def get_loopback():
+    import ifaddr
+    for adapter in ifaddr.get_adapters():
+        if adapter.name.startswith('lo'):
+            return adapter.name
+    return None
+
+
+def test_browser_setup():
+    loopback = get_loopback()
+    assert loopback is not None, 'Could not find loopback interface'
+    config = AirDropConfig(interface=loopback)
+    browser = AirDropBrowser(config)
+    browser.start()
+    browser.stop()