Mention number of errors found (#31)

src/pytest_plus/__init__.py

@@ -72,7 +72,7 @@ def pytest_collection_modifyitems(items: list[pytest.Item]) -> None:
  f"Test {item} has an id that does not match our safe pattern '{test_id_regex.pattern}' for use with a terminal.",
  )
  if errors:
- msg = f"Failed run due to following issues being identified:\n{os.linesep.join(errors)}"
+ msg = f"Failed run due to following issues being identified:\n{os.linesep.join(errors)}\nTotal errors found: {len(errors)}"
  raise pytest.UsageError(
  msg,
  )