108 lines
3.6 KiB
Python
108 lines
3.6 KiB
Python
"""
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Unit tests for randomized selection algorithm.
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Author: Carlos Gutierrez
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Course: MSCS532 - Data Structures and Algorithms
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"""
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import pytest
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from src.randomized_algorithm import randomized_select, find_median
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class TestRandomizedSelect:
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"""Test cases for randomized_select function."""
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def test_basic_selection(self):
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"""Test basic selection operations."""
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arr = [3, 1, 4, 1, 5, 9, 2, 6]
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assert randomized_select(arr, 1, seed=42) == 1
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assert randomized_select(arr, 2, seed=42) == 1
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assert randomized_select(arr, 3, seed=42) == 2
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assert randomized_select(arr, 4, seed=42) == 3
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assert randomized_select(arr, len(arr), seed=42) == 9
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def test_sorted_array(self):
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"""Test on sorted array."""
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arr = list(range(1, 11))
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for i in range(1, 11):
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assert randomized_select(arr, i, seed=42) == i
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def test_reverse_sorted_array(self):
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"""Test on reverse-sorted array."""
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arr = list(range(10, 0, -1))
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for i in range(1, 11):
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assert randomized_select(arr, i, seed=42) == i
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def test_duplicate_elements(self):
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"""Test with duplicate elements."""
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arr = [5, 5, 5, 3, 3, 1, 1, 1]
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assert randomized_select(arr, 1, seed=42) == 1
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assert randomized_select(arr, 2, seed=42) == 1
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assert randomized_select(arr, 3, seed=42) == 1
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assert randomized_select(arr, 4, seed=42) == 3
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assert randomized_select(arr, 5, seed=42) == 3
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assert randomized_select(arr, 6, seed=42) == 5
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def test_single_element(self):
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"""Test with single element."""
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arr = [42]
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assert randomized_select(arr, 1, seed=42) == 42
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def test_empty_array(self):
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"""Test with empty array."""
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with pytest.raises(IndexError):
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randomized_select([], 1)
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def test_invalid_k(self):
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"""Test with invalid k values."""
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arr = [1, 2, 3]
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with pytest.raises(ValueError):
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randomized_select(arr, 0)
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with pytest.raises(ValueError):
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randomized_select(arr, 4)
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def test_key_function(self):
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"""Test with custom key function."""
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arr = [{'value': 3}, {'value': 1}, {'value': 2}]
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result = randomized_select(arr, 2, key=lambda x: x['value'], seed=42)
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assert result['value'] == 2
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def test_large_array(self):
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"""Test with larger array."""
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arr = list(range(100, 0, -1))
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assert randomized_select(arr, 50, seed=42) == 50
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assert randomized_select(arr, 1, seed=42) == 1
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assert randomized_select(arr, 100, seed=42) == 100
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def test_reproducibility(self):
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"""Test that results are reproducible with same seed."""
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arr = [3, 1, 4, 1, 5, 9, 2, 6]
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result1 = randomized_select(arr, 4, seed=42)
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result2 = randomized_select(arr, 4, seed=42)
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assert result1 == result2
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class TestFindMedian:
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"""Test cases for find_median function."""
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def test_odd_length(self):
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"""Test median of odd-length array."""
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arr = [3, 1, 4, 1, 5]
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assert find_median(arr, seed=42) == 3
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def test_even_length(self):
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"""Test median of even-length array (returns lower median)."""
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arr = [3, 1, 4, 1, 5, 9]
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assert find_median(arr, seed=42) == 3
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def test_sorted_array(self):
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"""Test median of sorted array."""
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arr = list(range(1, 11))
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assert find_median(arr, seed=42) == 5
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def test_empty_array(self):
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"""Test median of empty array."""
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with pytest.raises(ValueError):
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find_median([])
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