diff --git a/src/auto_archiver/core/base_module.py b/src/auto_archiver/core/base_module.py
index fcfe9ea..5c6ecbb 100644
--- a/src/auto_archiver/core/base_module.py
+++ b/src/auto_archiver/core/base_module.py
@@ -63,7 +63,7 @@ class BaseModule(ABC):
     def setup(self, config: dict):
 
         authentication = config.get('authentication', {})
-        # extract out contatenated sites
+        # extract out concatenated sites
         for key, val in copy(authentication).items():
             if "," in key:
                 for site in key.split(","):
diff --git a/src/auto_archiver/core/config.py b/src/auto_archiver/core/config.py
index 2d462e4..8f36c54 100644
--- a/src/auto_archiver/core/config.py
+++ b/src/auto_archiver/core/config.py
@@ -36,6 +36,7 @@ steps:""" + "".join([f"\n   {module}s: []" for module in BaseModule.MODULE_TYPES
 # a dictionary of authentication information that can be used by extractors to login to website. 
 # you can use a comma separated list for multiple domains on the same line (common usecase: x.com,twitter.com)
 # Common login 'types' are username/password, cookie, api key/token.
+# There are two special keys for using cookies, they are: cookies_file and cookies_from_browser. 
 # Some Examples:
 # facebook.com:
 #   username: "my_username"
@@ -163,6 +164,6 @@ def read_yaml(yaml_filename: str) -> CommentedMap:
 def store_yaml(config: CommentedMap, yaml_filename: str) -> None:
     config_to_save = deepcopy(config)
 
-    config.pop('urls', None)
+    config_to_save.pop('urls', None)
     with open(yaml_filename, "w", encoding="utf-8") as outf:
         yaml.dump(config_to_save, outf)
\ No newline at end of file
diff --git a/src/auto_archiver/core/extractor.py b/src/auto_archiver/core/extractor.py
index 57320df..794c06c 100644
--- a/src/auto_archiver/core/extractor.py
+++ b/src/auto_archiver/core/extractor.py
@@ -17,7 +17,7 @@ from loguru import logger
 from retrying import retry
 import re
 
-from ..core import Metadata, BaseModule
+from auto_archiver.core import Metadata, BaseModule
 
 
 class Extractor(BaseModule):
diff --git a/src/auto_archiver/core/module.py b/src/auto_archiver/core/module.py
index dec67e1..f3fbec5 100644
--- a/src/auto_archiver/core/module.py
+++ b/src/auto_archiver/core/module.py
@@ -13,7 +13,7 @@ import copy
 import sys
 from importlib.util import find_spec
 import os
-from os.path import join, dirname
+from os.path import join
 from loguru import logger
 import auto_archiver
 from .base_module import BaseModule
@@ -64,8 +64,10 @@ def get_module_lazy(module_name: str, suppress_warnings: bool = False) -> LazyBa
     if module_name in _LAZY_LOADED_MODULES:
         return _LAZY_LOADED_MODULES[module_name]
 
-    module = available_modules(limit_to_modules=[module_name], suppress_warnings=suppress_warnings)[0]
-    return module
+    available = available_modules(limit_to_modules=[module_name], suppress_warnings=suppress_warnings)
+    if not available:
+        raise IndexError(f"Module '{module_name}' not found. Are you sure it's installed/exists?")
+    return available[0]
 
 def available_modules(with_manifest: bool=False, limit_to_modules: List[str]= [], suppress_warnings: bool = False) -> List[LazyBaseModule]:
     
diff --git a/src/auto_archiver/core/orchestrator.py b/src/auto_archiver/core/orchestrator.py
index 5ac091c..a451443 100644
--- a/src/auto_archiver/core/orchestrator.py
+++ b/src/auto_archiver/core/orchestrator.py
@@ -19,7 +19,7 @@ from rich_argparse import RichHelpFormatter
 
 
 from .metadata import Metadata, Media
-from ..version import __version__
+from auto_archiver.version import __version__
 from .config import yaml, read_yaml, store_yaml, to_dot_notation, merge_dicts, EMPTY_CONFIG, DefaultValidatingParser
 from .module import available_modules, LazyBaseModule, get_module, setup_paths
 from . import validators, Feeder, Extractor, Database, Storage, Formatter, Enricher
@@ -111,7 +111,6 @@ class ArchivingOrchestrator:
         # if full, we'll load all modules
         # TODO: BUG** - basic_config won't have steps in it, since these args aren't added to 'basic_parser'
         # but should we add them? Or should we just add them to the 'complete' parser?
-
         if yaml_config != EMPTY_CONFIG:
             # only load the modules enabled in config
             # TODO: if some steps are empty (e.g. 'feeders' is empty), should we default to the 'simple' ones? Or only if they are ALL empty?
@@ -128,6 +127,10 @@ class ArchivingOrchestrator:
         elif basic_config.mode == 'simple':
             simple_modules = [module for module in available_modules(with_manifest=True) if not module.requires_setup]
             self.add_module_args(simple_modules, parser)
+
+            # for simple mode, we use the cli_feeder and any modules that don't require setup
+            yaml_config['steps']['feeders'] = ['cli_feeder']
+            
             # add them to the config
             for module in simple_modules:
                 for module_type in module.type:
@@ -237,18 +240,18 @@ class ArchivingOrchestrator:
         if log_file := logging_config['file']:
             logger.add(log_file) if not logging_config['rotation'] else logger.add(log_file, rotation=logging_config['rotation'])
 
-        
-    def install_modules(self):
+    def install_modules(self, modules_by_type):
         """
-        Swaps out the previous 'strings' in the config with the actual modules and loads them
+        Traverses all modules in 'steps' and loads them into the orchestrator, storing them in the 
+        orchestrator's attributes (self.feeders, self.extractors etc.). If no modules of a certain type
+        are loaded, the program will exit with an error message.
         """
         
         invalid_modules = []
         for module_type in BaseModule.MODULE_TYPES:
 
             step_items = []
-            modules_to_load = self.config['steps'][f"{module_type}s"]
-
+            modules_to_load = modules_by_type[f"{module_type}s"]
             assert modules_to_load, f"No {module_type}s were configured. Make sure to set at least one {module_type} in your configuration file or on the command line (using --{module_type}s)"
 
             def check_steps_ok():
@@ -264,9 +267,10 @@ class ArchivingOrchestrator:
 
             for module in modules_to_load:
                 if module == 'cli_feeder':
+                    # pseudo module, don't load it
                     urls = self.config['urls']
                     if not urls:
-                        logger.error("No URLs provided. Please provide at least one URL to archive, or set up a feeder. Use --help for more information.")
+                        logger.error("No URLs provided. Please provide at least one URL via the command line, or set up an alternative feeder. Use --help for more information.")
                         exit()
                     # cli_feeder is a pseudo module, it just takes the command line args
                     def feed(self) -> Generator[Metadata]:
@@ -330,7 +334,7 @@ class ArchivingOrchestrator:
         self.setup_complete_parser(basic_config, yaml_config, unused_args)
 
         logger.info(f"======== Welcome to the AUTO ARCHIVER ({__version__}) ==========")
-        self.install_modules()
+        self.install_modules(self.config['steps'])
 
         # log out the modules that were loaded
         for module_type in BaseModule.MODULE_TYPES:
diff --git a/src/auto_archiver/modules/generic_extractor/generic_extractor.py b/src/auto_archiver/modules/generic_extractor/generic_extractor.py
index d1b1fb6..86e978f 100644
--- a/src/auto_archiver/modules/generic_extractor/generic_extractor.py
+++ b/src/auto_archiver/modules/generic_extractor/generic_extractor.py
@@ -6,7 +6,7 @@ from yt_dlp.extractor.common import InfoExtractor
 from loguru import logger
 
 from auto_archiver.core.extractor import Extractor
-from ...core import Metadata, Media
+from auto_archiver.core import Metadata, Media
 
 class GenericExtractor(Extractor):
     _dropins = {}
diff --git a/src/auto_archiver/modules/hash_enricher/hash_enricher.py b/src/auto_archiver/modules/hash_enricher/hash_enricher.py
index 58c6abe..b3ca8be 100644
--- a/src/auto_archiver/modules/hash_enricher/hash_enricher.py
+++ b/src/auto_archiver/modules/hash_enricher/hash_enricher.py
@@ -12,6 +12,7 @@ from loguru import logger
 
 from auto_archiver.core import Enricher
 from auto_archiver.core import Metadata
+from auto_archiver.utils.misc import calculate_file_hash
 
 
 class HashEnricher(Enricher):
@@ -35,9 +36,4 @@ class HashEnricher(Enricher):
         elif self.algorithm == "SHA3-512":
             hash = hashlib.sha3_512()
         else: return ""
-        with open(filename, "rb") as f:
-            while True:
-                buf = f.read(self.chunksize)
-                if not buf: break
-                hash.update(buf)
-        return hash.hexdigest()
+        return calculate_file_hash(filename, hash, self.chunksize)
diff --git a/src/auto_archiver/modules/s3_storage/s3_storage.py b/src/auto_archiver/modules/s3_storage/s3_storage.py
index 0c0e275..2f85164 100644
--- a/src/auto_archiver/modules/s3_storage/s3_storage.py
+++ b/src/auto_archiver/modules/s3_storage/s3_storage.py
@@ -7,9 +7,7 @@ from loguru import logger
 
 from auto_archiver.core import Media
 from auto_archiver.core import Storage
-from auto_archiver.modules.hash_enricher import HashEnricher
-from auto_archiver.utils.misc import random_str
-from auto_archiver.core.module import get_module
+from auto_archiver.utils.misc import calculate_file_hash, random_str
 
 NO_DUPLICATES_FOLDER = "no-dups/"
 
@@ -43,15 +41,13 @@ class S3Storage(Storage):
                     extra_args['ContentType'] = media.mimetype
             except Exception as e:
                 logger.warning(f"Unable to get mimetype for {media.key=}, error: {e}")
-
         self.s3.upload_fileobj(file, Bucket=self.bucket, Key=media.key, ExtraArgs=extra_args)
         return True
     
     def is_upload_needed(self, media: Media) -> bool:
         if self.random_no_duplicate:
             # checks if a folder with the hash already exists, if so it skips the upload
-            he = get_module('hash_enricher', self.config)
-            hd = he.calculate_hash(media.filename)
+            hd = calculate_file_hash(media.filename)
             path = os.path.join(NO_DUPLICATES_FOLDER, hd[:24])
 
             if existing_key:=self.file_in_folder(path):
diff --git a/src/auto_archiver/modules/telethon_extractor/telethon_extractor.py b/src/auto_archiver/modules/telethon_extractor/telethon_extractor.py
index 947db9e..97d3e94 100644
--- a/src/auto_archiver/modules/telethon_extractor/telethon_extractor.py
+++ b/src/auto_archiver/modules/telethon_extractor/telethon_extractor.py
@@ -6,7 +6,7 @@ from telethon.tl.functions.messages import ImportChatInviteRequest
 from telethon.errors.rpcerrorlist import UserAlreadyParticipantError, FloodWaitError, InviteRequestSentError, InviteHashExpiredError
 from loguru import logger
 from tqdm import tqdm
-import re, time, json, os
+import re, time, os
 
 from auto_archiver.core import Extractor
 from auto_archiver.core import Metadata, Media
diff --git a/src/auto_archiver/core/authentication.py b/src/auto_archiver/utils/gsheet.py
similarity index 100%
rename from src/auto_archiver/core/authentication.py
rename to src/auto_archiver/utils/gsheet.py
diff --git a/src/auto_archiver/utils/misc.py b/src/auto_archiver/utils/misc.py
index e4c214c..2b64a3d 100644
--- a/src/auto_archiver/utils/misc.py
+++ b/src/auto_archiver/utils/misc.py
@@ -3,6 +3,7 @@ import json
 import uuid
 from datetime import datetime, timezone
 import requests
+import hashlib
 from loguru import logger
 
 
@@ -52,6 +53,7 @@ def update_nested_dict(dictionary, update_dict):
         else:
             dictionary[key] = value
 
+
 def random_str(length: int = 32) -> str:
     assert length <= 32, "length must be less than 32 as UUID4 is used"
     return str(uuid.uuid4()).replace("-", "")[:length]
@@ -60,6 +62,15 @@ def random_str(length: int = 32) -> str:
 def json_loader(cli_val):
     return json.loads(cli_val)
 
+
+def calculate_file_hash(filename: str, hash_algo = hashlib.sha256(), chunksize: int = 16000000) -> str:
+    with open(filename, "rb") as f:
+        while True:
+            buf = f.read(chunksize)
+            if not buf: break
+            hash_algo.update(buf)
+    return hash_algo.hexdigest()
+
 def get_current_datetime_iso() -> str:
     return datetime.now(timezone.utc).replace(tzinfo=timezone.utc).isoformat()
 
diff --git a/tests/test_implementation.py b/tests/test_implementation.py
new file mode 100644
index 0000000..7e33651
--- /dev/null
+++ b/tests/test_implementation.py
@@ -0,0 +1,62 @@
+import sys
+import pytest
+
+from auto_archiver.__main__ import main
+
+
+@pytest.fixture
+def orchestration_file_path(tmp_path):
+    return (tmp_path / "example_orch.yaml").as_posix()
+
+@pytest.fixture
+def orchestration_file(orchestration_file_path):
+    def _orchestration_file(content=''):
+        with open(orchestration_file_path, "w") as f:
+            f.write(content)
+        return orchestration_file_path
+    
+    return _orchestration_file
+
+@pytest.fixture
+def autoarchiver(tmp_path, monkeypatch, request):
+    def _autoarchiver(args=[]):
+
+        def cleanup():
+            from loguru import logger
+            if not logger._core.handlers.get(0):
+                logger._core.handlers_count = 0
+                logger.add(sys.stderr)
+
+        request.addfinalizer(cleanup)
+
+        # change dir to tmp_path
+        monkeypatch.chdir(tmp_path)
+        with monkeypatch.context() as m:
+            m.setattr(sys, "argv", ["auto-archiver"] + args)
+            return main()
+
+    return _autoarchiver
+
+
+def test_run_auto_archiver_no_args(caplog, autoarchiver):
+    with pytest.raises(SystemExit):
+        autoarchiver()
+
+    assert "provide at least one URL via the command line, or set up an alternative feeder" in caplog.text
+
+def test_run_auto_archiver_invalid_file(caplog, autoarchiver):
+    # exec 'auto-archiver' on the command lin
+    with pytest.raises(SystemExit):
+        autoarchiver(["--config", "nonexistent_file.yaml"])
+
+    assert "Make sure the file exists and try again, or run without th" in caplog.text
+
+def test_run_auto_archiver_empty_file(caplog, autoarchiver, orchestration_file):
+    # create a valid (empty) orchestration file
+    path = orchestration_file(content="")
+    # exec 'auto-archiver' on the command lin
+    with pytest.raises(SystemExit):
+        autoarchiver(["--config", path])
+
+    # should treat an empty file as if there is no file at all
+    assert " No URLs provided. Please provide at least one URL via the com" in caplog.text