fix(SecureDropConfig): pass "env" for inferring debug mode

The interactions among our "env" and "DEBUG" and Flask's "ENV" and
"DEBUG" are not ideal, but refactoring them is well beyond the scope of
this fix.

securedrop/sdconfig.py

@@ -71,6 +71,8 @@ class SecureDropConfig:
 
     RQ_WORKER_NAME: str
 
+    env: str = "prod"
+
     @property
     def TEMP_DIR(self) -> Path:
         # We use a directory under the SECUREDROP_DATA_ROOT instead of `/tmp` because
@@ -115,6 +117,8 @@ def _parse_config_from_file(config_module_name: str) -> SecureDropConfig:
         config_from_local_file, "SCRYPT_PARAMS", dict(N=2**14, r=8, p=1)
     )
 
+    env = getattr(config_from_local_file, "env", "prod")
+
     try:
         final_securedrop_root = Path(config_from_local_file.SECUREDROP_ROOT)
     except AttributeError:
@@ -188,6 +192,7 @@ def _parse_config_from_file(config_module_name: str) -> SecureDropConfig:
     )
 
     return SecureDropConfig(
+        env=env,
         JOURNALIST_APP_FLASK_CONFIG_CLS=parsed_journ_flask_config,
         SOURCE_APP_FLASK_CONFIG_CLS=parsed_source_flask_config,
         GPG_KEY_DIR=final_gpg_key_dir,

securedrop/tests/test_config.py

@@ -19,8 +19,12 @@ def test_parse_current_config():
     try:
         current_config_file.write_text(current_sample_config.read_text())
 
-        # When trying to parse it, it succeeds
-        assert _parse_config_from_file(f"tests.{current_config_module}")
+        # When trying to parse it, it succeeds...
+        parsed_config = _parse_config_from_file(f"tests.{current_config_module}")
+        assert parsed_config
+
+        # ...and has one of our `env` values rather than one of Flask's:
+        assert parsed_config.env in ["prod", "dev", "test"]
 
     finally:
         current_config_file.unlink(missing_ok=True)