Changes sk_path to sk_der in Watcher

The Watcher used to receive a secret key file path ion the __init__ to load a secret key for signing. That made testing the Watcher hard, since the file needed to be present. Changing it so the main (pisad) loads the file from disk and passes the data the Watcher on init.

test/unit/test_watcher.py

@@ -2,13 +2,20 @@ import pytest
 from uuid import uuid4
 from threading import Thread
 from queue import Queue, Empty
+from cryptography.hazmat.primitives import serialization
 
 from pisa import c_logger
 from pisa.watcher import Watcher
 from pisa.responder import Responder
 from pisa.tools import bitcoin_cli
-from test.unit.conftest import generate_block, generate_blocks, generate_dummy_appointment, get_random_value_hex
-from pisa.conf import EXPIRY_DELTA, PISA_SECRET_KEY, MAX_APPOINTMENTS
+from test.unit.conftest import (
+    generate_block,
+    generate_blocks,
+    generate_dummy_appointment,
+    get_random_value_hex,
+    generate_keypair,
+)
+from pisa.conf import EXPIRY_DELTA, MAX_APPOINTMENTS
 
 from common.tools import check_sha256_hex_format
 from common.cryptographer import Cryptographer
@@ -20,15 +27,18 @@ START_TIME_OFFSET = 1
 END_TIME_OFFSET = 1
 TEST_SET_SIZE = 200
 
-with open(PISA_SECRET_KEY, "rb") as key_file_der:
-    sk_der = key_file_der.read()
-    signing_key = Cryptographer.load_private_key_der(sk_der)
-    public_key = signing_key.public_key()
+
+signing_key, public_key = generate_keypair()
+sk_der = signing_key.private_bytes(
+    encoding=serialization.Encoding.DER,
+    format=serialization.PrivateFormat.TraditionalOpenSSL,
+    encryption_algorithm=serialization.NoEncryption(),
+)
 
 
 @pytest.fixture(scope="module")
 def watcher(db_manager):
-    return Watcher(db_manager)
+    return Watcher(db_manager, sk_der)
 
 
 @pytest.fixture(scope="module")
@@ -69,15 +79,6 @@ def test_init(watcher):
     assert type(watcher.responder) is Responder
 
 
-def test_init_no_key(db_manager):
-    try:
-        Watcher(db_manager, pisa_sk_file=None)
-        assert False
-
-    except ValueError:
-        assert True
-
-
 def test_add_appointment(run_bitcoind, watcher):
     # The watcher automatically fires do_watch and do_subscribe on adding an appointment if it is asleep (initial state)
     # Avoid this by setting the state to awake.