Do not use side-effects of import to initialize hardware plugins

Call HidTransport in the context of a function

plugins/keepkey/keepkey.py

@@ -11,11 +11,25 @@ class KeepKeyPlugin(TrezorCompatiblePlugin):
     libraries_URL = 'https://github.com/keepkey/python-keepkey'
     minimum_firmware = (1, 0, 0)
     keystore_class = KeepKey_KeyStore
-    try:
+
-        from .client import KeepKeyClient as client_class
+    def __init__(self, *args):
-        import keepkeylib.ckd_public as ckd_public
+        try:
-        from keepkeylib.client import types
+            import client
-        from keepkeylib.transport_hid import HidTransport, DEVICE_IDS
+            import keepkeylib
-        libraries_available = True
+            import keepkeylib.ckd_public
-    except ImportError:
+            import keepkeylib.transport_hid
-        libraries_available = False
+            self.client_class = client.KeepKeyClient
+            self.ckd_public = keepkeylib.ckd_public
+            self.types = keepkeylib.client.types
+            self.DEVICE_IDS = keepkeylib.transport_hid.DEVICE_IDS
+            self.libraries_available = True
+        except ImportError:
+            self.libraries_available = False
+        TrezorCompatiblePlugin.__init__(self, *args)
+
+    def hid_transport(self, pair):
+        from keepkeylib.transport_hid import HidTransport
+        return HidTransport(pair)
+
+    def bridge_transport(self, d):
+        raise NotImplementedError('')

plugins/trezor/plugin.py

@@ -99,7 +99,7 @@ class TrezorCompatiblePlugin(HW_PluginBase):
             pair = [device.path, None]
 
         try:
-            return self.HidTransport(pair)
+            return self.hid_transport(pair)
         except BaseException as e:
             raise
             self.print_error("cannot connect at", device.path, str(e))
@@ -109,7 +109,7 @@ class TrezorCompatiblePlugin(HW_PluginBase):
         self.print_error("Trying to connect over Trezor Bridge...")
 
         try:
-            return self.BridgeTransport({'path': hexlify(device.path)})
+            return self.bridge_transport({'path': hexlify(device.path)})
         except BaseException as e:
             self.print_error("cannot connect to bridge", str(e))
             return None

plugins/trezor/trezor.py

@@ -10,12 +10,26 @@ class TrezorPlugin(TrezorCompatiblePlugin):
     libraries_URL = 'https://github.com/trezor/python-trezor'
     minimum_firmware = (1, 3, 3)
     keystore_class = TrezorKeyStore
-    try:
+
-        from .client import TrezorClient as client_class
+    def __init__(self, *args):
-        import trezorlib.ckd_public as ckd_public
+        try:
-        from trezorlib.client import types
+            import client
-        from trezorlib.transport_hid import HidTransport, DEVICE_IDS
+            import trezorlib
+            import trezorlib.ckd_public
+            import trezorlib.transport_hid
+            self.client_class = client.TrezorClient
+            self.ckd_public = trezorlib.ckd_public
+            self.types = trezorlib.client.types
+            self.DEVICE_IDS = trezorlib.transport_hid.DEVICE_IDS
+            self.libraries_available = True
+        except ImportError:
+            self.libraries_available = False
+        TrezorCompatiblePlugin.__init__(self, *args)
+
+    def hid_transport(self, pair):
+        from trezorlib.transport_hid import HidTransport
+        return HidTransport(pair)
+
+    def bridge_transport(self, d):
         from trezorlib.transport_bridge import BridgeTransport
-        libraries_available = True
+        return BridgeTransport(d)
-    except ImportError:
-        libraries_available = False