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Testing Lazy Evaluation Pattern Implementation in python-patterns

This test suite validates the lazy evaluation pattern implementation in Python, focusing on dynamic property expansion and attribute access counting. It verifies proper initialization of Person objects and tests lazy loading of properties like relatives and parents.

Test Coverage Overview

The test suite provides comprehensive coverage of lazy evaluation mechanics in a Person class.

Key areas tested include:

Initial property initialization verification
Dynamic property expansion tracking
Attribute access counting
Lazy loading of relative information
Multiple access patterns for cached properties

Implementation Analysis

The testing approach uses unittest framework to systematically verify lazy evaluation behavior. The suite employs a combination of property presence checks, dictionary state verification, and access counting to ensure correct implementation.

Key patterns tested:

Property access tracking
Dictionary state management
Cached property behavior
Multiple access scenarios

Technical Details

Testing infrastructure:

Python unittest framework
setUp method for test isolation
assertDictEqual for state verification
assertIn/assertNotIn for property presence checks
assertEqual for value validation

Best Practices Demonstrated

The test suite exemplifies several testing best practices:

Isolated test cases with proper setup
Comprehensive state verification
Multiple assertion types for thorough validation
Clear test case naming conventions
Systematic property access verification

faif/python-patterns

tests/creational/test_lazy.py

            
import unittest

from patterns.creational.lazy_evaluation import Person


class TestDynamicExpanding(unittest.TestCase):
    def setUp(self):
        self.John = Person("John", "Coder")

    def test_innate_properties(self):
        self.assertDictEqual(
            {"name": "John", "occupation": "Coder", "call_count2": 0},
            self.John.__dict__,
        )

    def test_relatives_not_in_properties(self):
        self.assertNotIn("relatives", self.John.__dict__)

    def test_extended_properties(self):
        print(f"John's relatives: {self.John.relatives}")
        self.assertDictEqual(
            {
                "name": "John",
                "occupation": "Coder",
                "relatives": "Many relatives.",
                "call_count2": 0,
            },
            self.John.__dict__,
        )

    def test_relatives_after_access(self):
        print(f"John's relatives: {self.John.relatives}")
        self.assertIn("relatives", self.John.__dict__)

    def test_parents(self):
        for _ in range(2):
            self.assertEqual(self.John.parents, "Father and mother")
        self.assertEqual(self.John.call_count2, 1)