fix: make extra_name of try_import optional and the install hint reusable

src/crawlee/_utils/try_import.py

@@ -12,29 +12,44 @@
 
 
 @contextmanager
-def try_import(module_name: str, *symbol_names: str, extra_name: str | list[str]) -> Iterator[None]:
+def try_import(
+    module_name: str,
+    *symbol_names: str,
+    extra_name: str | list[str] | None = None,
+    package_name: str = 'crawlee',
+) -> Iterator[None]:
     """Context manager to attempt importing symbols into a module.
 
     If an `ImportError` is raised during the import, the symbols are replaced with `FailedImport` objects. When the
-    error is a `ModuleNotFoundError`, the message also names the optional extra (or one of several) that installs the
-    missing dependency. Other import errors, including those raised by a nested guard, keep their message as is.
+    error is a `ModuleNotFoundError` and `extra_name` is given, the message also names the optional extra (or one of
+    several) that installs the missing dependency. Other import errors, including those raised by a nested guard,
+    keep their message as is.
+
+    Args:
+        module_name: The name of the module the symbols are imported into.
+        symbol_names: The names of the symbols being imported.
+        extra_name: The optional extra (or extras) providing the dependency. When omitted, the error message is
+            left as it is.
+        package_name: The distribution whose extras are named in the message. Defaults to this package, and exists
+            so that downstream packages reusing this helper can point users at their own extras.
     """
     try:
         yield
     except ImportError as e:
-        message = e.args[0]
-        if isinstance(e, ModuleNotFoundError):
-            message = f'{message}. {_get_install_hint(extra_name)}'
+        message = str(e)
+        if isinstance(e, ModuleNotFoundError) and extra_name:
+            message = f'{message}. {_get_install_hint(extra_name, package_name)}'
         for symbol_name in symbol_names:
             setattr(sys.modules[module_name], symbol_name, FailedImport(message))
 
 
-def _get_install_hint(extra_name: str | list[str]) -> str:
+def _get_install_hint(extra_name: str | list[str], package_name: str) -> str:
     """Build the sentence telling the user which extra installs the missing optional dependency."""
-    if isinstance(extra_name, str):
-        return f"Install the optional '{extra_name}' extra to use it: pip install 'crawlee[{extra_name}]'"
-    extras = ', '.join(f"'{name}'" for name in extra_name)
-    return f"Install one of the optional extras {extras} to use it, e.g. pip install 'crawlee[{extra_name[0]}]'"
+    extras = [extra_name] if isinstance(extra_name, str) else list(extra_name)
+    if len(extras) == 1:
+        return f"Install the optional '{extras[0]}' extra to use it: pip install '{package_name}[{extras[0]}]'"
+    names = ', '.join(f"'{name}'" for name in extras)
+    return f"Install one of the optional extras {names} to use it, e.g. pip install '{package_name}[{extras[0]}]'"
 
 
 def install_import_hook(module_name: str) -> None:

tests/unit/_utils/test_try_import.py

@@ -52,3 +52,29 @@ def test_nested_guard_keeps_the_inner_message(module_name: str, monkeypatch: pyt
 
     assert sys.modules[module_name].OptionalSymbol.message == inner_message
     assert inner_message.count('pip install') == 1
+
+
+def test_omitted_extra_keeps_the_original_message(module_name: str) -> None:
+    """Without `extra_name` the message is left as it is, so external callers of the helper keep working."""
+    with try_import(module_name, 'OptionalSymbol'):
+        raise ModuleNotFoundError("No module named 'parsel'", name='parsel')
+
+    assert sys.modules[module_name].OptionalSymbol.message == "No module named 'parsel'"
+
+
+def test_install_hint_names_the_given_package(module_name: str) -> None:
+    """Downstream packages reusing the helper can point users at their own extras."""
+    with try_import(module_name, 'OptionalSymbol', extra_name='scrapy', package_name='apify'):
+        raise ModuleNotFoundError("No module named 'scrapy'", name='scrapy')
+
+    assert sys.modules[module_name].OptionalSymbol.message == (
+        "No module named 'scrapy'. Install the optional 'scrapy' extra to use it: pip install 'apify[scrapy]'"
+    )
+
+
+def test_import_error_without_arguments_is_handled(module_name: str) -> None:
+    """An `ImportError` carrying no message does not break the guard itself."""
+    with try_import(module_name, 'OptionalSymbol', extra_name='parsel'):
+        raise ImportError
+
+    assert sys.modules[module_name].OptionalSymbol.message == ''