Make RPCError subclasses unpicklable again (#1387)

tests/telethon/test_pickle.py

@@ -0,0 +1,35 @@
+import pickle
+
+from telethon.errors import RPCError, BadRequestError, FileIdInvalidError, NetworkMigrateError
+
+
+def _assert_equality(error, unpickled_error):
+    assert error.code == unpickled_error.code
+    assert error.message == unpickled_error.message
+    assert type(error) == type(unpickled_error)
+    assert str(error) == str(unpickled_error)
+
+
+def test_base_rpcerror_pickle():
+    error = RPCError("request", "message", 123)
+    unpickled_error = pickle.loads(pickle.dumps(error))
+    _assert_equality(error, unpickled_error)
+
+
+def test_rpcerror_pickle():
+    error = BadRequestError("request", "BAD_REQUEST", 400)
+    unpickled_error = pickle.loads(pickle.dumps(error))
+    _assert_equality(error, unpickled_error)
+
+
+def test_fancy_rpcerror_pickle():
+    error = FileIdInvalidError("request")
+    unpickled_error = pickle.loads(pickle.dumps(error))
+    _assert_equality(error, unpickled_error)
+
+
+def test_fancy_rpcerror_capture_pickle():
+    error = NetworkMigrateError(request="request", capture=5)
+    unpickled_error = pickle.loads(pickle.dumps(error))
+    _assert_equality(error, unpickled_error)
+    assert error.new_dc == unpickled_error.new_dc