Bring-your own-plugins (BYOP), via --custom-plugins option

[KevinHock]

This is an exact replica of #255, I just don't have the GitHub permissions to push to the branch any more, so I made this one. 😄

[KevinHock]

re: @OiCMudkips feedback, I changed the following. It's much nicer now :)

diff --git a/detect_secrets/core/audit.py b/detect_secrets/core/audit.py
index f50dd93..92d418b 100644
--- a/detect_secrets/core/audit.py
+++ b/detect_secrets/core/audit.py
@@ -290,13 +290,13 @@ def determine_audit_results(baseline, baseline_path):
         audit_results['stats'][audit_result]['count'] += 1
         audit_results['stats'][audit_result]['files'][filename] += 1
         total += 1
-    audit_results['stats']['signal'] = '{:.2f}'.format(
+    audit_results['stats']['signal'] = '{:.2f}%'.format(
         (
             float(audit_results['stats']['true-positives']['count'])
             /
             total
         ) * 100,
-    ) + '%'
+    )
 
     for plugin_config in baseline['plugins_used']:
         plugin_name = plugin_config['name']
@@ -339,7 +339,10 @@ def print_audit_results(baseline_filename):
 def _get_baseline_from_file(filename):  # pragma: no cover
     try:
         with open(filename) as f:
-            return json.loads(f.read())
+            baseline = json.loads(f.read())
+            if 'custom_plugin_paths' in baseline:
+                baseline['custom_plugin_paths'] = tuple(baseline['custom_plugin_paths'])
+            return baseline
     except (IOError, json.decoder.JSONDecodeError):
         print('Not a valid baseline file!', file=sys.stderr)
         return
@@ -507,8 +510,8 @@ def _print_context(  # pragma: no cover
         ...     },
         ... ]
 
-    :type custom_plugin_paths: List[str]
-    :param custom_plugin_paths: possibly empty list of paths that have custom plugins.
+    :type custom_plugin_paths: Tuple[str]
+    :param custom_plugin_paths: possibly empty tuple of paths that have custom plugins.
 
     :type additional_header_lines: str
     :param additional_header_lines: any additional lines to add to the
@@ -649,8 +652,8 @@ def _get_secret_with_context(
         ...     },
         ... ]
 
-    :type custom_plugin_paths: List[str]
-    :param custom_plugin_paths: possibly empty list of paths that have custom plugins.
+    :type custom_plugin_paths: Tuple[str]
+    :param custom_plugin_paths: possibly empty tuple of paths that have custom plugins.
 
     :type lines_of_context: int
     :param lines_of_context: number of lines displayed before and after
@@ -720,8 +723,8 @@ def get_raw_secret_value(
         ...     },
         ... ]
 
-    :type custom_plugin_paths: List[str]
-    :param custom_plugin_paths: possibly empty list of paths that have custom plugins.
+    :type custom_plugin_paths: Tuple[str]
+    :param custom_plugin_paths: possibly empty tuple of paths that have custom plugins.
 
     :type file_handle: file object
     :param file_handle: Open handle to file where the secret is
diff --git a/detect_secrets/core/baseline.py b/detect_secrets/core/baseline.py
index a6f12e1..d74b7db 100644
--- a/detect_secrets/core/baseline.py
+++ b/detect_secrets/core/baseline.py
@@ -29,8 +29,8 @@ def initialize(
     :type plugins: tuple of detect_secrets.plugins.base.BasePlugin
     :param plugins: rules to initialize the SecretsCollection with.
 
-    :type custom_plugin_paths: List[str]
-    :param custom_plugin_paths: possibly empty list of paths that have custom plugins.
+    :type custom_plugin_paths: Tuple[str]
+    :param custom_plugin_paths: possibly empty tuple of paths that have custom plugins.
 
     :type exclude_files_regex: str|None
     :type exclude_lines_regex: str|None
diff --git a/detect_secrets/core/secrets_collection.py b/detect_secrets/core/secrets_collection.py
index 04184ef..b76e2f5 100644
--- a/detect_secrets/core/secrets_collection.py
+++ b/detect_secrets/core/secrets_collection.py
@@ -28,8 +28,8 @@ class SecretsCollection:
         :type plugins: tuple of detect_secrets.plugins.base.BasePlugin
         :param plugins: rules to determine whether a string is a secret
 
-        :type custom_plugin_paths: List[str]|None
-        :param custom_plugin_paths: possibly empty list of paths that have custom plugins.
+        :type custom_plugin_paths: Tuple[str]|None
+        :param custom_plugin_paths: possibly empty tuple of paths that have custom plugins.
 
         :type exclude_files: str|None
         :param exclude_files: optional regex for ignored paths.
@@ -47,7 +47,7 @@ class SecretsCollection:
         self.version = VERSION
 
         self.plugins = plugins
-        self.custom_plugin_paths = custom_plugin_paths or []
+        self.custom_plugin_paths = custom_plugin_paths or ()
         self.exclude_files = exclude_files
         self.exclude_lines = exclude_lines
         self.word_list_file = word_list_file
@@ -116,7 +116,7 @@ class SecretsCollection:
                 automaton, result.word_list_hash = build_automaton(result.word_list_file)
 
         # In v0.12.8 the `--custom-plugins` option got added
-        result.custom_plugin_paths = data.get('custom_plugin_paths', [])
+        result.custom_plugin_paths = data.get('custom_plugin_paths', ())
 
         plugins = []
         for plugin in data['plugins_used']:
diff --git a/detect_secrets/core/usage.py b/detect_secrets/core/usage.py
index 149c554..eacbf71 100644
--- a/detect_secrets/core/usage.py
+++ b/detect_secrets/core/usage.py
@@ -4,7 +4,6 @@ from collections import namedtuple
 from functools import lru_cache
 
 from detect_secrets import VERSION
-from detect_secrets.plugins.common.util import change_custom_plugin_paths_to_tuple
 from detect_secrets.plugins.common.util import import_plugins
 
 
@@ -28,11 +27,33 @@ def add_word_list_argument(parser):
     )
 
 
+def _is_valid_path(path):  # pragma: no cover
+    if not os.path.exists(path):
+        raise argparse.ArgumentTypeError(
+            'Invalid path: {}'.format(path),
+        )
+
+    return path
+
+
+class TupleAction(argparse.Action):
+    def __call__(self, parser, namespace, values, options_string=None):
+        existing_values = getattr(
+            namespace,
+            self.dest,
+        )
+        setattr(
+            namespace,
+            self.dest,
+            existing_values + (values,),
+        )
+
+
 def add_custom_plugins_argument(parser):
     parser.add_argument(
         '--custom-plugins',
-        action='append',
-        default=[],
+        action=TupleAction,
+        default=(),
         dest='custom_plugin_paths',
         help=(
             'Custom plugin Python files, or directories containing them. '
@@ -42,15 +63,6 @@ def add_custom_plugins_argument(parser):
     )
 
 
-def _is_valid_path(path):  # pragma: no cover
-    if not os.path.exists(path):
-        raise argparse.ArgumentTypeError(
-            'Invalid path: {}'.format(path),
-        )
-
-    return path
-
-
 def add_use_all_plugins_argument(parser):
     parser.add_argument(
         '--use-all-plugins',
@@ -378,7 +390,6 @@ class PluginDescriptor(
         return 'Disables {}'.format(line)
 
 
-@change_custom_plugin_paths_to_tuple
 @lru_cache(maxsize=1)
 def get_all_plugin_descriptors(custom_plugin_paths):
     return [
diff --git a/detect_secrets/plugins/common/initialize.py b/detect_secrets/plugins/common/initialize.py
index 135e3b8..a09c27e 100644
--- a/detect_secrets/plugins/common/initialize.py
+++ b/detect_secrets/plugins/common/initialize.py
@@ -16,8 +16,8 @@ def from_parser_builder(
     :param plugins_dict: plugins dictionary received from ParserBuilder.
         See example in tests.core.usage_test.
 
-    :type custom_plugin_paths: List[str]
-    :param custom_plugin_paths: possibly empty list of paths that have custom plugins.
+    :type custom_plugin_paths: Tuple[str]
+    :param custom_plugin_paths: possibly empty tuple of paths that have custom plugins.
 
     :type exclude_lines_regex: str|None
     :param exclude_lines_regex: optional regex for ignored lines.
@@ -163,8 +163,8 @@ def from_plugin_classname(
     :type plugin_classname: str
     :param plugin_classname: subclass of BasePlugin.
 
-    :type custom_plugin_paths: List[str]
-    :param custom_plugin_paths: possibly empty list of paths that have custom plugins.
+    :type custom_plugin_paths: Tuple[str]
+    :param custom_plugin_paths: possibly empty tuple of paths that have custom plugins.
 
     :type exclude_lines_regex: str|None
     :param exclude_lines_regex: optional regex for ignored lines.
@@ -219,8 +219,8 @@ def from_secret_type(secret_type, plugins_used, custom_plugin_paths):
         ...     },
         ... ]
 
-    :type custom_plugin_paths: List[str]
-    :param custom_plugin_paths: possibly empty list of paths that have custom plugins.
+    :type custom_plugin_paths: Tuple[str]
+    :param custom_plugin_paths: possibly empty tuple of paths that have custom plugins.
     """
     mapping = get_mapping_from_secret_type_to_class_name(custom_plugin_paths)
     try:
diff --git a/detect_secrets/plugins/common/util.py b/detect_secrets/plugins/common/util.py
index 6891446..3210925 100644
--- a/detect_secrets/plugins/common/util.py
+++ b/detect_secrets/plugins/common/util.py
@@ -8,21 +8,6 @@ from detect_secrets.plugins.base import BasePlugin
 from detect_secrets.util import get_root_directory
 
 
-def change_custom_plugin_paths_to_tuple(custom_plugin_paths_function):
-    """
-    :type custom_plugin_paths_function: function
-    A function that takes one argument named custom_plugin_paths
-
-    :returns: function
-    The custom_plugin_paths_function with it's arg changed to a tuple
-    """
-    def wrapper_of_custom_plugin_paths_function(custom_plugin_paths):
-        return custom_plugin_paths_function(tuple(custom_plugin_paths))
-
-    return wrapper_of_custom_plugin_paths_function
-
-
-@change_custom_plugin_paths_to_tuple
 @lru_cache(maxsize=1)
 def get_mapping_from_secret_type_to_class_name(custom_plugin_paths):
     """Returns dictionary of secret_type => plugin classname"""
@@ -64,7 +49,6 @@ def _is_valid_concrete_plugin_class(attr):
     )
 
 
-@change_custom_plugin_paths_to_tuple
 @lru_cache(maxsize=1)
 def import_plugins(custom_plugin_paths):
     """
diff --git a/testing/util.py b/testing/util.py
index aa9743e..fbddb09 100644
--- a/testing/util.py
+++ b/testing/util.py
@@ -20,7 +20,7 @@ def uncolor(text):
 def get_regex_based_plugins():
     return {
         name: plugin
-        for name, plugin in import_plugins(custom_plugin_paths=[]).items()
+        for name, plugin in import_plugins(custom_plugin_paths=()).items()
         if issubclass(plugin, RegexBasedDetector)
     }
 
diff --git a/tests/core/audit_test.py b/tests/core/audit_test.py
index 64419ae..063388e 100644
--- a/tests/core/audit_test.py
+++ b/tests/core/audit_test.py
@@ -240,7 +240,7 @@ class TestAuditBaseline:
     @property
     def baseline(self):
         return {
-            'custom_plugin_paths': [],
+            'custom_plugin_paths': (),
             'generated_at': 'some timestamp',
             'plugins_used': [
                 {
@@ -273,7 +273,7 @@ class TestAuditBaseline:
     @property
     def leapfrog_baseline(self):
         return {
-            'custom_plugin_paths': [],
+            'custom_plugin_paths': (),
             'generated_at': 'some timestamp',
             'plugins_used': [
                 {
@@ -399,7 +399,7 @@ class TestCompareBaselines:
     @property
     def old_baseline(self):
         return {
-            'custom_plugin_paths': [],
+            'custom_plugin_paths': (),
             'plugins_used': [
                 {
                     'name': 'Base64HighEntropyString',
@@ -444,7 +444,7 @@ class TestCompareBaselines:
     @property
     def new_baseline(self):
         return {
-            'custom_plugin_paths': [],
+            'custom_plugin_paths': (),
             'plugins_used': [
                 {
                     'name': 'Base64HighEntropyString',
@@ -528,7 +528,7 @@ class TestDetermineAuditResults:
         audited.
         """
         baseline_fixture = {
-            'custom_plugin_paths': [],
+            'custom_plugin_paths': (),
             'plugins_used': plugins_used,
             'results': {
                 'mocked_file': [
@@ -762,7 +762,7 @@ class TestPrintContext:
             audit._print_context(
                 filename=secret.filename,
                 secret=secret.json(),
-                custom_plugin_paths=[],
+                custom_plugin_paths=(),
                 count=1,
                 total=2,
                 plugins_used=plugins_used,
diff --git a/tests/core/baseline_test.py b/tests/core/baseline_test.py
index bf4a533..22b10cb 100644
--- a/tests/core/baseline_test.py
+++ b/tests/core/baseline_test.py
@@ -35,7 +35,7 @@ class TestInitializeBaseline:
         return baseline.initialize(
             path,
             self.plugins,
-            custom_plugin_paths=[],
+            custom_plugin_paths=(),
             exclude_files_regex=exclude_files_regex,
             should_scan_all_files=scan_all_files,
         ).json()
diff --git a/tests/core/secrets_collection_test.py b/tests/core/secrets_collection_test.py
index cb411e9..76e078f 100644
--- a/tests/core/secrets_collection_test.py
+++ b/tests/core/secrets_collection_test.py
@@ -350,7 +350,7 @@ class TestBaselineInputOutput:
 
         # v0.12.8+ assertions
         assert 'custom_plugin_paths' not in original
-        assert secrets['custom_plugin_paths'] == []
+        assert secrets['custom_plugin_paths'] == ()
 
         # v0.12.7+ assertions
         assert original['word_list']['file'] == secrets['word_list']['file']
@@ -390,7 +390,7 @@ class TestBaselineInputOutput:
     def get_point_twelve_point_eight_and_later_baseline_dict(self, gmtime):
         # In v0.12.8 --custom-plugins got added
         baseline = self.get_point_twelve_point_seven_and_later_baseline_dict(gmtime)
-        baseline['custom_plugin_paths'] = []
+        baseline['custom_plugin_paths'] = ()
         return baseline
 
     def get_point_twelve_point_seven_and_later_baseline_dict(self, gmtime):
diff --git a/tests/core/usage_test.py b/tests/core/usage_test.py
index 345f6d5..94a29f2 100644
--- a/tests/core/usage_test.py
+++ b/tests/core/usage_test.py
@@ -19,7 +19,7 @@ class TestPluginOptions:
 
         regex_based_plugins = {
             key: {}
-            for key in import_plugins(custom_plugin_paths=[])
+            for key in import_plugins(custom_plugin_paths=())
         }
         regex_based_plugins.update({
             'HexHighEntropyString': {
@@ -65,3 +65,22 @@ class TestPluginOptions:
         else:
             with pytest.raises(SystemExit):
                 parse_pre_commit_args_with_correct_prog(argument_string)
+
+    @pytest.mark.parametrize(
+        'argument_string,expected_value',
+        [
+            ('--custom-plugins testing', ('testing',)),
+            ('--custom-plugins does_not_exist', None),
+        ],
+    )
+    def test_custom_plugins(self, argument_string, expected_value):
+        if expected_value is not None:
+            args = parse_pre_commit_args_with_correct_prog(argument_string)
+
+            assert (
+                args.custom_plugin_paths
+                == expected_value
+            )
+        else:
+            with pytest.raises(SystemExit):
+                parse_pre_commit_args_with_correct_prog(argument_string)
diff --git a/tests/main_test.py b/tests/main_test.py
index 004817c..182e1bf 100644
--- a/tests/main_test.py
+++ b/tests/main_test.py
@@ -30,7 +30,7 @@ def get_list_of_plugins(include=None, exclude=None):
         ]
 
     output = []
-    for name, plugin in import_plugins(custom_plugin_paths=[]).items():
+    for name, plugin in import_plugins(custom_plugin_paths=()).items():
         if (
             name in included_plugins or
             exclude and name in exclude
@@ -59,7 +59,7 @@ def get_plugin_report(extra=None):
 
     longest_name_length = max([
         len(name)
-        for name in import_plugins(custom_plugin_paths=[])
+        for name in import_plugins(custom_plugin_paths=())
     ])
 
     return '\n'.join(
@@ -68,7 +68,7 @@ def get_plugin_report(extra=None):
                 name=name + ' ' * (longest_name_length - len(name)),
                 result='False' if name not in extra else extra[name],
             )
-            for name in import_plugins(custom_plugin_paths=[])
+            for name in import_plugins(custom_plugin_paths=())
         ]),
     ) + '\n'
 
@@ -84,7 +84,7 @@ class TestMain:
 
         mock_baseline_initialize.assert_called_once_with(
             plugins=Any(tuple),
-            custom_plugin_paths=Any(list),
+            custom_plugin_paths=Any(tuple),
             exclude_files_regex=None,
             exclude_lines_regex=None,
             path='.',
@@ -99,7 +99,7 @@ class TestMain:
 
         mock_baseline_initialize.assert_called_once_with(
             plugins=Any(tuple),
-            custom_plugin_paths=Any(list),
+            custom_plugin_paths=Any(tuple),
             exclude_files_regex=None,
             exclude_lines_regex=None,
             path=['test_data'],
@@ -116,7 +116,7 @@ class TestMain:
 
         mock_baseline_initialize.assert_called_once_with(
             plugins=Any(tuple),
-            custom_plugin_paths=Any(list),
+            custom_plugin_paths=Any(tuple),
             exclude_files_regex='some_pattern_here',
             exclude_lines_regex='other_patt',
             path='.',
@@ -183,7 +183,7 @@ class TestMain:
 
         mock_baseline_initialize.assert_called_once_with(
             plugins=Any(tuple),
-            custom_plugin_paths=Any(list),
+            custom_plugin_paths=Any(tuple),
             exclude_files_regex=None,
             exclude_lines_regex=None,
             path='.',
@@ -492,6 +492,7 @@ class TestMain:
             baseline = printer_shim.message
 
         baseline_dict = json.loads(baseline)
+        baseline_dict['custom_plugin_paths'] = tuple(baseline_dict['custom_plugin_paths'])
         with mock_stdin(), mock.patch(
             # To pipe in printer_shim
             'detect_secrets.core.audit._get_baseline_from_file',
@@ -559,6 +560,7 @@ class TestMain:
             baseline = printer_shim.message
 
         baseline_dict = json.loads(baseline)
+        baseline_dict['custom_plugin_paths'] = tuple(baseline_dict['custom_plugin_paths'])
         with mock.patch(
             'detect_secrets.core.audit._get_baseline_from_file',
             return_value=baseline_dict,
diff --git a/tests/plugins/common/initialize_test.py b/tests/plugins/common/initialize_test.py
index 6205a72..b9ef5d6 100644
--- a/tests/plugins/common/initialize_test.py
+++ b/tests/plugins/common/initialize_test.py
@@ -11,7 +11,7 @@ class TestFromPluginClassname:
     def test_success(self):
         plugin = initialize.from_plugin_classname(
             plugin_classname='HexHighEntropyString',
-            custom_plugin_paths=[],
+            custom_plugin_paths=(),
             hex_limit=4,
         )
 
@@ -27,7 +27,7 @@ class TestFromPluginClassname:
         with pytest.raises(TypeError):
             initialize.from_plugin_classname(
                 plugin_classname='NotABasePlugin',
-                custom_plugin_paths=[],
+                custom_plugin_paths=(),
             )
 
     def test_fails_on_bad_initialization(self):
@@ -40,7 +40,7 @@ class TestFromPluginClassname:
         ):
             initialize.from_plugin_classname(
                 plugin_classname='HexHighEntropyString',
-                custom_plugin_paths=[],
+                custom_plugin_paths=(),
                 hex_limit=4,
             )
 
@@ -62,7 +62,7 @@ class TestFromSecretType:
         plugin = initialize.from_secret_type(
             'Base64 High Entropy String',
             plugins_used=self.plugins_used,
-            custom_plugin_paths=[],
+            custom_plugin_paths=(),
         )
         # Dynamically imported classes have different
         # addresses for the same functions as statically
@@ -76,12 +76,12 @@ class TestFromSecretType:
         assert not initialize.from_secret_type(
             'some random secret_type',
             plugins_used=self.plugins_used,
-            custom_plugin_paths=[],
+            custom_plugin_paths=(),
         )
 
     def test_secret_type_not_in_settings(self):
         assert not initialize.from_secret_type(
             'Base64 High Entropy String',
             plugins_used=[],
-            custom_plugin_paths=[],
+            custom_plugin_paths=(),
         )

[KevinHock]

This is ready for review @OiCMudkips (no hurry though)

[KevinHock]

\o/

Thanks!!!