fix: make TEST_X_API_KEY use an environment variable of the same name

test/__init__.py

@@ -1,18 +1,27 @@
+from os import getenv
 from unittest import skipIf
 
 from fathomnet.api import xapikey
 
-# Set this to an API key in order to perform authentication and enable test cases decorated by @skipIfNoAuth
-TEST_X_API_KEY = None
+# Set the TEST_X_API_KEY environment variable an API key in order to perform authentication and enable test cases decorated by @skipIfNoAuth
+TEST_X_API_KEY = getenv("TEST_X_API_KEY")
 
-
-if (
-    TEST_X_API_KEY is not None
-):  # If test X-API-Key is provided, authenticate session to enable cases
+# If test X-API-Key is provided, authenticate session to enable cases
+if TEST_X_API_KEY is not None:
     xapikey.auth(TEST_X_API_KEY)
 
 
-def skipIfNoAuth(f):  # Decorator to skip test case if it needs auth
+def skipIfNoAuth(f: callable) -> callable:
+    """
+    Decorator to skip test case if it needs auth.
+
+    Args:
+        f (callable): Test case function.
+
+    Returns:
+        callable: Test case function
+    """
     return skipIf(
-        TEST_X_API_KEY is None, "Test X-API-Key not specified. (see test/__init__.py)"
+        TEST_X_API_KEY is None,
+        "TEST_X_API_KEY environment variable not specified",
     )(f)