pytest: Consolidate access to environment variables

We use `env()` to look up configuration variables and allow them to be
overridden by the environment.

tests/fixtures.py

@@ -1,29 +1,16 @@
 from concurrent import futures
 from db import SqliteDbProvider, PostgresDbProvider
-from utils import NodeFactory, BitcoinD, ElementsD
+from utils import NodeFactory, BitcoinD, ElementsD, env
+from utils import DEVELOPER, TEST_NETWORK  # noqa: F401,F403
 
 import logging
 import os
 import pytest
 import re
 import shutil
-import sys
 import tempfile
 
 
-with open('config.vars') as configfile:
-    config = dict([(line.rstrip().split('=', 1)) for line in configfile])
-
-VALGRIND = os.getenv("VALGRIND", config['VALGRIND']) == "1"
-TEST_NETWORK = os.getenv("TEST_NETWORK", config['TEST_NETWORK'])
-DEVELOPER = os.getenv("DEVELOPER", config['DEVELOPER']) == "1"
-TEST_DEBUG = os.getenv("TEST_DEBUG", "0") == "1"
-
-
-if TEST_DEBUG:
-    logging.basicConfig(level=logging.DEBUG, stream=sys.stdout)
-
-
 # A dict in which we count how often a particular test has run so far. Used to
 # give each attempt its own numbered directory, and avoid clashes.
 __attempts = {}
@@ -31,7 +18,7 @@ __attempts = {}
 
 @pytest.fixture(scope="session")
 def test_base_dir():
-    d = os.getenv("TEST_DIR", "/tmp")
+    d = env("TEST_DIR", "/tmp")
 
     directory = tempfile.mkdtemp(prefix='ltests-', dir=d)
     print("Running tests in {}".format(directory))
@@ -83,7 +70,7 @@ network_daemons = {
 
 @pytest.fixture
 def bitcoind(directory, teardown_checks):
-    chaind = network_daemons[config.get('TEST_NETWORK', 'regtest')]
+    chaind = network_daemons[env('TEST_NETWORK', 'regtest')]
     bitcoind = chaind(bitcoin_dir=directory)
 
     try:
@@ -332,4 +319,4 @@ def chainparams():
         }
     }
 
-    return chainparams[config['TEST_NETWORK']]
+    return chainparams[env('TEST_NETWORK', 'regtest')]

tests/utils.py

@@ -19,6 +19,7 @@ import struct
 import subprocess
 import threading
 import time
+import sys
 
 BITCOIND_CONFIG = {
     "regtest": 1,
@@ -36,22 +37,42 @@ LIGHTNINGD_CONFIG = OrderedDict({
     'disable-dns': None,
 })
 
-with open('config.vars') as configfile:
-    config = dict([(line.rstrip().split('=', 1)) for line in configfile])
 
-DEVELOPER = os.getenv("DEVELOPER", config['DEVELOPER']) == "1"
+def env(name, default=None):
-EXPERIMENTAL_FEATURES = os.getenv("EXPERIMENTAL_FEATURES", config['EXPERIMENTAL_FEATURES']) == "1"
+    """Access to environment variables
 
-# Gossip can be slow without DEVELOPER.
+    Allows access to environment variables, falling back to config.vars (part
-if DEVELOPER:
+    of c-lightning's `./configure` output), and finally falling back to a
-    DEFAULT_TIMEOUT = 60
+    default value.
+
+    """
+    fname = 'config.vars'
+    if os.path.exists(fname):
+        lines = open(fname, 'r').readlines()
+        config = dict([(line.rstrip().split('=', 1)) for line in lines])
     else:
-    DEFAULT_TIMEOUT = 180
+        config = {}
 
-TIMEOUT = int(os.getenv("TIMEOUT", str(DEFAULT_TIMEOUT)))
+    if name in os.environ:
-VALGRIND = os.getenv("VALGRIND", config['VALGRIND']) == "1"
+        return os.environ[name]
-SLOW_MACHINE = os.getenv("SLOW_MACHINE", "0") == "1"
+    elif name in config:
-COMPAT = os.getenv("COMPAT", config['COMPAT']) == "1"
+        return config[name]
+    else:
+        return default
+
+
+VALGRIND = env("VALGRIND") == "1"
+TEST_NETWORK = env("TEST_NETWORK", 'regtest')
+DEVELOPER = env("DEVELOPER", "1") == "1"
+TEST_DEBUG = env("TEST_DEBUG", "0") == "1"
+SLOW_MACHINE = env("SLOW_MACHINE", "0") == "1"
+COMPAT = env("COMPAT", "1") == "1"
+EXPERIMENTAL_FEATURES = os.getenv("EXPERIMENTAL_FEATURES", "0") == "1"
+TIMEOUT = int(env("TIMEOUT", 180 if SLOW_MACHINE else 60))
+
+
+if TEST_DEBUG:
+    logging.basicConfig(level=logging.DEBUG, stream=sys.stdout)
 
 
 def wait_for(success, timeout=TIMEOUT):
@@ -459,7 +480,7 @@ class LightningD(TailableProc):
             'lightning-dir': lightning_dir,
             'addr': '127.0.0.1:{}'.format(port),
             'allow-deprecated-apis': 'false',
-            'network': config.get('TEST_NETWORK', 'regtest'),
+            'network': env('TEST_NETWORK', 'regtest'),
             'ignore-fee-limits': 'false',
             'bitcoin-rpcuser': BITCOIND_CONFIG['rpcuser'],
             'bitcoin-rpcpassword': BITCOIND_CONFIG['rpcpassword'],