Read default registry configuration at construction

spectator/registry.py

@@ -19,7 +19,9 @@
 class Registry:
     """Registry is the main entry point for interacting with the Spectator library."""
 
-    def __init__(self, config: Config = Config()) -> None:
+    def __init__(self, config: Optional[Config] = None) -> None:
+        if config is None:
+            config = Config()
         self._logger = logging.getLogger(__name__)
         self._config = config
         if config.is_global:

tests/test_registry.py

@@ -1,12 +1,33 @@
 import ctypes
 import logging
+import os
 import unittest
+from unittest.mock import patch
 
 from spectator import Config, MemoryWriter, Registry
 
 
 class RegistryTest(unittest.TestCase):
 
+    def test_default_config_reads_current_environment(self):
+        with patch.dict(os.environ, {"SPECTATOR_OUTPUT_LOCATION": "memory",
+                                     "NETFLIX_PROCESS_NAME": "worker"}):
+            registry = Registry()
+            self.addCleanup(registry.close)
+            self.assertIsInstance(registry.writer(), MemoryWriter)
+            self.assertEqual("worker", registry.new_id("requests").tags()["nf.process"])
+
+    def test_default_config_refreshes_between_registries(self):
+        with patch.dict(os.environ, {"SPECTATOR_OUTPUT_LOCATION": "memory",
+                                     "NETFLIX_PROCESS_NAME": "first"}):
+            first = Registry()
+            self.addCleanup(first.close)
+            os.environ["NETFLIX_PROCESS_NAME"] = "second"
+            second = Registry()
+            self.addCleanup(second.close)
+            self.assertEqual("first", first.new_id("requests").tags()["nf.process"])
+            self.assertEqual("second", second.new_id("requests").tags()["nf.process"])
+
     def test_close(self):
         r = Registry(Config("memory"))