absl.testing.flagsaver module

Decorator and context manager for saving and restoring flag values.

There are many ways to save and restore. Always use the most convenient method for a given use case.

Here are examples of each method. They all call do_stuff() while FLAGS.someflag is temporarily set to ‘foo’.

from absl.testing import flagsaver

# Use a decorator which can optionally override flags via arguments. @flagsaver.flagsaver(someflag=’foo’) def some_func():

do_stuff()

# Use a decorator which can optionally override flags with flagholders. @flagsaver.flagsaver((module.FOO_FLAG, ‘foo’), (other_mod.BAR_FLAG, 23)) def some_func():

do_stuff()

# Use a decorator which does not override flags itself. @flagsaver.flagsaver def some_func():

FLAGS.someflag = ‘foo’ do_stuff()

# Use a context manager which can optionally override flags via arguments. with flagsaver.flagsaver(someflag=’foo’):

do_stuff()

# Save and restore the flag values yourself. saved_flag_values = flagsaver.save_flag_values() try:

FLAGS.someflag = ‘foo’ do_stuff()

finally:

flagsaver.restore_flag_values(saved_flag_values)

We save and restore a shallow copy of each Flag object’s __dict__ attribute. This preserves all attributes of the flag, such as whether or not it was overridden from its default value.

WARNING: Currently a flag that is saved and then deleted cannot be restored. An exception will be raised. However if you add a flag after saving flag values, and then restore flag values, the added flag will be deleted with no errors.

absl.testing.flagsaver.flagsaver(*args, **kwargs)

The main flagsaver interface. See module doc for usage.

absl.testing.flagsaver.restore_flag_values(saved_flag_values, flag_values=<absl.flags._flagvalues.FlagValues object>)

Restores flag values based on the dictionary of flag values.

Parameters

• saved_flag_values – {‘flag_name’: value_dict, …}

• flag_values – FlagValues, the FlagValues instance from which the flag will be restored. This should almost never need to be overridden.

absl.testing.flagsaver.save_flag_values(flag_values=<absl.flags._flagvalues.FlagValues object>)

Returns copy of flag values as a dict.

Parameters

flag_values – FlagValues, the FlagValues instance with which the flag will be saved. This should almost never need to be overridden.

Returns

Dictionary mapping keys to values. Keys are flag names, values are corresponding __dict__ members. E.g. {‘key’: value_dict, …}.