Glossary: mocks, modules and namespaces — DedSec Project

Mock

Definition and boundaries

A controlled test replacement for a real dependency. It can simulate a timeout and verify calls but cannot establish that a real server follows the same request/response protocol.

Working miniature

from unittest.mock import Mock
send=Mock(return_value={'ok':True})
assert send('hi')['ok']
send.assert_called_once_with('hi')

Guided investigation

Configure TimeoutError using side_effect, assert the caller handles it, then run an integration test against an authorized sandbox.

Check your understanding

For Mock, change one input in the example and explain whether the observed behavior still satisfies the stated definition. Record the exact output and distinguish a program error from a mistaken assumption.

Module

Definition and boundaries

Named unit that groups reusable definitions. Python runs a module's top-level statements on import, so module organization alone cannot ensure code has no side effects.

Working miniature

from math import isfinite
assert isfinite(2.5)
assert not isfinite(float('nan'))

Guided investigation

Move a parser to parser.py and a command-line entry point to cli.py. Use if name == 'main' to prevent unexpected execution at import.

Check your understanding

For Module, change one input in the example and explain whether the observed behavior still satisfies the stated definition. Record the exact output and distinguish a program error from a mistaken assumption.

Namespace

Definition and boundaries

Mapping from identifiers to objects in a scope or module. Qualifying an imported function avoids name collisions, but a namespace does not enforce authorization or memory isolation.

Working miniature

import math
import statistics
assert math.sqrt(9)==statistics.mean([3,3])

Guided investigation

Create a local sqrt binding and compare access through math.sqrt. Trace which definition each expression resolves to.

Check your understanding

For Namespace, change one input in the example and explain whether the observed behavior still satisfies the stated definition. Record the exact output and distinguish a program error from a mistaken assumption.

Null

Precise meaning

Explicit absence marker different from 0, false and empty text. Python None, JSON null and JavaScript null/undefined do not share identical rules.

Reference experiment

import json
assert json.loads('null') is None
assert json.loads('0') == 0
assert json.loads('""') == ''

Investigate the boundary

Represent absent nickname, nickname=None and nickname='' separately. Test whether a truthiness check accidentally merges them.

Independent check

For Null, document the expected outcome before running the sample. Change one important assumption and decide whether the failure belongs to the caller, the implementation or the environment.

Object

Precise meaning

A runtime value with identity, properties and possibly methods. Separate instances can hold independent state even if constructed by the same class.

Reference experiment

class Counter:
    def __init__(self): self.value=0
    def inc(self): self.value+=1
a,b=Counter(),Counter(); a.inc()
assert (a.value,b.value)==(1,0)

Investigate the boundary

Add a mutable class-level list and observe unintended sharing; move it into init to repair the ownership boundary.

Independent check

For Object, document the expected outcome before running the sample. Change one important assumption and decide whether the failure belongs to the caller, the implementation or the environment.