Add length override to secrets collection to fix pretty output of pre…

…-commit hook diagnostic total secrets

detect_secrets/core/secrets_collection.py

@@ -308,6 +308,10 @@ def __sub__(self, other: Any) -> 'SecretsCollection':
 
         return output
 
+    def __len__(self) -> int:
+        """Returns the total number of secrets in the collection."""
+        return sum(len(secrets) for secrets in self.data.values())
+
 
 def _scan_file_and_serialize(filename: str) -> List[PotentialSecret]:
     """Used for multiprocessing, since lambdas can't be serialized."""

tests/pre_commit_hook_test.py

@@ -98,6 +98,7 @@ def test_console_output():
     # Assert formatting
     output = capturedOutput.getvalue()
     assert output.startswith('ERROR: Potential secrets about to be committed to git repo!')
+    assert 'Total secrets detected: 1' in output
 
 
 def test_console_output_json_formatting():