Merge #658: trezor: Add missing import and minor test fixes following…

… passphrase changes

b8a379c test, trezor: Properly pass empty string passphrase (Andrew Chow)
c3f490f test, trezor: Check for warnings rather than needs_passphrase_sent (Andrew Chow)
203c844 trezor: Add missing NoPasswordError import (Andrew Chow)

Pull request description:

  Fixes a couple things were missed following #644 which are causing CI failures in Trezor tests.

Top commit has no ACKs.

Tree-SHA512: 508c6c9cdbc18833360a146296293500480938723843927e980e124ab24cb17f035418623e7fcb3e1a196e3e6bb7754bdd3bd2903d5d9064918ad875124efd1a

hwilib/devices/trezor.py

@@ -26,6 +26,7 @@
     DeviceConnectionError,
     DEVICE_NOT_INITIALIZED,
     DeviceNotReadyError,
+    NoPasswordError,
     UnavailableActionError,
     common_err_msgs,
     handle_errors,

test/test_trezor.py

@@ -340,7 +340,7 @@ def test_passphrase(self):
         result = self.do_command(self.dev_args + ['enumerate'])
         for dev in result:
             if dev['type'] == 'trezor' and dev['path'] == 'udp:127.0.0.1:21324':
-                self.assertTrue(dev['needs_passphrase_sent'])
+                self.assertIn("warnings", dev)
                 break
         else:
             self.fail("Did not enumerate device")
@@ -352,7 +352,7 @@ def test_passphrase(self):
                 break
         else:
             self.fail("Did not enumerate device")
-        result = self.do_command(self.dev_args + ['-p', '', 'enumerate'])
+        result = self.do_command(self.dev_args + ['-p', '\"\"', 'enumerate'])
         for dev in result:
             if dev['type'] == 'trezor' and dev['path'] == 'udp:127.0.0.1:21324':
                 self.assertFalse(dev['needs_passphrase_sent'])