Refactor signature DB init, deprecate test DB

mythril/mythril.py

@@ -17,6 +17,7 @@ from solc.exceptions import SolcError
 import solc
 from configparser import ConfigParser
 import platform
+from shutil import copyfile
 
 from mythril.ethereum import util
 from mythril.ethereum.evmcontract import EVMContract
@@ -116,11 +117,18 @@ class Mythril(object):
         except KeyError:
             mythril_dir = os.path.join(os.path.expanduser("~"), ".mythril")
 
-            # Initialize data directory and signature database
-
         if not os.path.exists(mythril_dir):
+            # Initialize data directory
             logging.info("Creating mythril data directory")
             os.mkdir(mythril_dir)
+
+        db_path = Path(mythril_dir) / "signatures.db"
+        if not os.path.exists(db_path):
+            # if the default mythril dir doesn't contain a signature DB
+            # initialize it with the default one from the project root
+            parent_dir = Path(__file__).parent.parent
+            copyfile(parent_dir / "signatures.db", db_path)
+
         return mythril_dir
 
     def _init_config(self):

tests/__init__.py

@@ -18,16 +18,6 @@ MYTHRIL_DIR = TESTS_DIR / "mythril_dir"
 class BaseTestCase(TestCase):
     def setUp(self):
         self.changed_files = []
-        self.ori_mythril_dir = os.environ.get("MYTHRIL_DIR", "")
-        os.environ["MYTHRIL_DIR"] = str(MYTHRIL_DIR)
-        shutil.copyfile(
-            str(MYTHRIL_DIR / "signatures.db.example"),
-            str(MYTHRIL_DIR / "signatures.db"),
-        )
-
-    def tearDown(self):
-        os.environ["MYTHRIL_DIR"] = self.ori_mythril_dir
-        os.remove(str(MYTHRIL_DIR / "signatures.db"))
 
     def compare_files_error_message(self):
         message = "Following output files are changed, compare them manually to see differences: \n"