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# Copyright (c) Microsoft Corporation. All rights reserved.
# Licensed under the MIT License.
import unittest
from unittest import mock
from azure.monitor.opentelemetry.exporter.export.trace._utils import (
_get_DJB2_sample_score,
)
# fixedint was removed as a source dependency. It is used as a dev requirement to test sample score
from fixedint import Int32
from azure.monitor.opentelemetry.exporter._constants import (
_SAMPLING_HASH,
_INT32_MAX,
_INT32_MIN,
)
class TestGetDJB2SampleScore(unittest.TestCase):
"""Test cases for _get_DJB2_sample_score function."""
def test_empty_string(self):
"""Test with empty string."""
result = _get_DJB2_sample_score("")
# With empty string, hash should remain _SAMPLING_HASH (5381)
# Result should be 5381 / _INT32_MAX
expected = float(5381) / _INT32_MAX
self.assertEqual(result, expected)
def test_single_character(self):
"""Test with single character."""
result = _get_DJB2_sample_score("a")
# hash = ((5381 << 5) + 5381) + ord('a')
# hash = (172192 + 5381) + 97 = 177670
expected_hash = ((5381 << 5) + 5381) + ord('a')
expected = float(expected_hash) / _INT32_MAX
self.assertEqual(result, expected)
def test_typical_trace_id(self):
"""Test with typical 32-character trace ID."""
trace_id = "12345678901234567890123456789012"
result = _get_DJB2_sample_score(trace_id)
# Manually calculate expected result
hash_value = Int32(_SAMPLING_HASH)
for char in trace_id:
hash_value = ((hash_value << 5) + hash_value) + ord(char)
if hash_value == _INT32_MIN:
hash_value = int(_INT32_MAX)
else:
hash_value = abs(hash_value)
expected = float(hash_value) / _INT32_MAX
self.assertEqual(result, expected)
def test_hex_characters(self):
"""Test with valid hex characters (0-9, a-f)."""
test_cases = [
"0123456789abcdef",
"fedcba9876543210",
"aaaaaaaaaaaaaaaa",
"0000000000000000",
"ffffffffffffffff"
]
for trace_id in test_cases:
with self.subTest(trace_id=trace_id):
result = _get_DJB2_sample_score(trace_id)
self.assertIsInstance(result, float)
self.assertGreaterEqual(result, 0.0)
self.assertLessEqual(result, 1.0)
def test_int32_overflow_handling(self):
"""Test that Int32 overflow is handled correctly."""
# Create a string that should cause overflow
long_string = "f" * 100 # 100 'f' characters should cause overflow
result = _get_DJB2_sample_score(long_string)
self.assertIsInstance(result, float)
self.assertGreaterEqual(result, 0.0)
self.assertLessEqual(result, 1.0)
def test_int32_minimum_value_handling(self):
"""Test handling when hash equals INTEGER_MIN."""
# This is tricky to test directly since we need to find a string
# that results in exactly _INT32_MIN. Instead, let's test the logic.
# We'll use a mock to simulate this condition
def mock_djb2_with_min_value(trace_id_hex):
# Call original to get the structure, then simulate _INT32_MIN case
hash_value = Int32(_SAMPLING_HASH)
for char in trace_id_hex:
hash_value = ((hash_value << 5) + hash_value) + ord(char)
# Simulate the case where we get _INT32_MIN
if str(trace_id_hex) == "test_min":
hash_value = Int32(_INT32_MIN)
if hash_value == _INT32_MIN:
hash_value = int(_INT32_MAX)
else:
hash_value = abs(hash_value)
return float(hash_value) / _INT32_MAX
# Test the _INT32_MIN case
result = mock_djb2_with_min_value("test_min")
expected = float(_INT32_MAX) / _INT32_MAX
self.assertEqual(result, expected)
def test_negative_hash_conversion(self):
"""Test that negative hash values are converted to positive."""
# Find a string that produces a negative hash
test_string = "negative_test_case_string"
result = _get_DJB2_sample_score(test_string)
# Result should always be positive (between 0 and 1)
self.assertGreaterEqual(result, 0.0)
self.assertLessEqual(result, 1.0)
def test_deterministic_output(self):
"""Test that same input always produces same output."""
trace_id = "abcdef1234567890abcdef1234567890"
# Call multiple times with same input
results = [_get_DJB2_sample_score(trace_id) for _ in range(5)]
# All results should be identical
self.assertTrue(all(r == results[0] for r in results))
def test_different_inputs_different_outputs(self):
"""Test that different inputs produce different outputs."""
trace_ids = [
"12345678901234567890123456789012",
"12345678901234567890123456789013", # Last digit different
"22345678901234567890123456789012", # First digit different
"abcdef1234567890fedcba0987654321", # Completely different
]
results = [_get_DJB2_sample_score(tid) for tid in trace_ids]
# All results should be different
self.assertEqual(len(results), len(set(results)))
def test_boundary_values(self):
"""Test with boundary values and edge cases."""
test_cases = [
"0", # Single minimum hex digit
"f", # Single maximum hex digit
"00000000000000000000000000000000", # All zeros
"ffffffffffffffffffffffffffffffff", # All f's (32 chars)
]
for trace_id in test_cases:
with self.subTest(trace_id=trace_id):
result = _get_DJB2_sample_score(trace_id)
self.assertIsInstance(result, float)
self.assertGreaterEqual(result, 0.0)
self.assertLessEqual(result, 1.0)
def test_constants_used_correctly(self):
"""Test that the function uses the expected constants."""
# Verify that _SAMPLING_HASH is 5381 (standard DJB2 hash initial value)
self.assertEqual(_SAMPLING_HASH, 5381)
# Verify Int32 constants
self.assertEqual(_INT32_MAX, 2147483647) # 2^31 - 1
self.assertEqual(_INT32_MIN, -2147483648) # -2^31
def test_algorithm_correctness(self):
"""Test that the DJB2 algorithm is implemented correctly."""
# Test with known input and manually calculated expected output
trace_id = "abc"
# Manual calculation:
# Start with 5381
# For 'a' (97): hash = ((5381 << 5) + 5381) + 97 = 177670
# For 'b' (98): hash = ((177670 << 5) + 177670) + 98 = 5823168
# For 'c' (99): hash = ((5823168 << 5) + 5823168) + 99 = 191582563
expected_hash = _SAMPLING_HASH
for char in trace_id:
expected_hash = Int32(((expected_hash << 5) + expected_hash) + ord(char))
if expected_hash == _INT32_MIN:
expected_hash = int(_INT32_MAX)
else:
expected_hash = abs(expected_hash)
expected_result = float(expected_hash) / _INT32_MAX
actual_result = _get_DJB2_sample_score(trace_id)
self.assertEqual(actual_result, expected_result)
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