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426"""Unit tests for circuit breaker implementation."""
import time
import pytest
from src.utils.circuit_breaker import CircuitBreaker, CircuitBreakerConfig, CircuitBreakerOpenError, CircuitState
@pytest.mark.unit
class TestCircuitBreakerStates:
"""Test circuit breaker state transitions."""
def test_initial_state_is_closed(self):
"""Circuit breaker should start in CLOSED state."""
breaker = CircuitBreaker("test")
assert breaker.state == CircuitState.CLOSED
assert breaker.is_closed
assert not breaker.is_open
assert not breaker.is_half_open
def test_closed_to_open_on_failures(self):
"""Circuit should open after reaching failure threshold."""
breaker = CircuitBreaker("test", failure_threshold=3)
# Record failures
breaker.record_failure()
assert breaker.is_closed # Still closed (1/3)
breaker.record_failure()
assert breaker.is_closed # Still closed (2/3)
breaker.record_failure()
assert breaker.is_open # Now open (3/3)
def test_success_resets_failure_count_in_closed(self):
"""Success in CLOSED state should reset failure count."""
breaker = CircuitBreaker("test", failure_threshold=3)
breaker.record_failure()
breaker.record_failure()
assert breaker.is_closed
# Success resets counter
breaker.record_success()
# Should take 3 more failures to open
breaker.record_failure()
breaker.record_failure()
assert breaker.is_closed # Still closed
breaker.record_failure()
assert breaker.is_open # Now opens
def test_open_to_half_open_after_timeout(self):
"""Circuit should transition to HALF_OPEN after timeout."""
breaker = CircuitBreaker("test", failure_threshold=2, timeout=0.1)
# Trigger open state
breaker.record_failure()
breaker.record_failure()
assert breaker.is_open
# Wait for timeout
time.sleep(0.15)
# Check state (triggers timeout check)
assert breaker.is_half_open
def test_half_open_to_closed_on_successes(self):
"""Circuit should close after enough successes in HALF_OPEN."""
breaker = CircuitBreaker(
"test",
failure_threshold=2,
success_threshold=2,
timeout=0.1
)
# Open circuit
breaker.record_failure()
breaker.record_failure()
assert breaker.is_open
# Wait for timeout
time.sleep(0.15)
assert breaker.is_half_open
# First success
breaker.check_state() # Allow call
breaker.record_success()
assert breaker.is_half_open # Still half-open (1/2)
# Second success -> closes
breaker.check_state()
breaker.record_success()
assert breaker.is_closed
def test_half_open_to_open_on_failure(self):
"""Failure in HALF_OPEN should immediately reopen circuit."""
breaker = CircuitBreaker("test", failure_threshold=2, timeout=0.1)
# Open circuit
breaker.record_failure()
breaker.record_failure()
assert breaker.is_open
# Transition to half-open
time.sleep(0.15)
assert breaker.is_half_open
# Failure immediately reopens
breaker.check_state()
breaker.record_failure()
assert breaker.is_open
@pytest.mark.unit
class TestCircuitBreakerBlocking:
"""Test circuit breaker request blocking behavior."""
def test_check_state_passes_when_closed(self):
"""check_state() should not raise when circuit is closed."""
breaker = CircuitBreaker("test")
breaker.check_state() # Should not raise
def test_check_state_raises_when_open(self):
"""check_state() should raise CircuitBreakerOpenError when open."""
breaker = CircuitBreaker("test", failure_threshold=1)
breaker.record_failure()
assert breaker.is_open
with pytest.raises(CircuitBreakerOpenError) as exc_info:
breaker.check_state()
assert "test" in str(exc_info.value)
assert "is open" in str(exc_info.value)
def test_half_open_allows_limited_concurrent_calls(self):
"""HALF_OPEN should allow only half_open_max_calls concurrent calls."""
breaker = CircuitBreaker(
"test",
failure_threshold=1,
timeout=0.1,
config=CircuitBreakerConfig(half_open_max_calls=2)
)
# Open circuit
breaker.record_failure()
assert breaker.is_open
# Transition to half-open
time.sleep(0.15)
assert breaker.is_half_open
# First call allowed
breaker.check_state()
# Second call allowed
breaker.check_state()
# Third call blocked (max is 2)
with pytest.raises(CircuitBreakerOpenError) as exc_info:
breaker.check_state()
assert "half-open" in str(exc_info.value).lower()
assert "max concurrent calls" in str(exc_info.value).lower()
def test_half_open_calls_decrement_on_completion(self):
"""Half-open call count should decrement after success/failure."""
breaker = CircuitBreaker(
"test",
failure_threshold=1,
timeout=0.1,
config=CircuitBreakerConfig(half_open_max_calls=1)
)
# Open and transition to half-open
breaker.record_failure()
time.sleep(0.15)
assert breaker.is_half_open
# Start call
breaker.check_state()
# Complete with success
breaker.record_success()
# Should allow another call now
breaker.check_state() # Should not raise
@pytest.mark.unit
class TestCircuitBreakerConfiguration:
"""Test circuit breaker configuration options."""
def test_custom_failure_threshold(self):
"""Test custom failure threshold configuration."""
breaker = CircuitBreaker("test", failure_threshold=10)
for i in range(9):
breaker.record_failure()
assert breaker.is_closed
breaker.record_failure() # 10th failure
assert breaker.is_open
def test_custom_success_threshold(self):
"""Test custom success threshold in half-open state."""
breaker = CircuitBreaker(
"test",
failure_threshold=1,
success_threshold=3,
timeout=0.1
)
# Open circuit
breaker.record_failure()
time.sleep(0.15)
assert breaker.is_half_open
# Need 3 successes to close
breaker.check_state()
breaker.record_success()
assert breaker.is_half_open
breaker.check_state()
breaker.record_success()
assert breaker.is_half_open
breaker.check_state()
breaker.record_success()
assert breaker.is_closed
def test_custom_timeout(self):
"""Test custom timeout configuration."""
breaker = CircuitBreaker("test", failure_threshold=1, timeout=0.5)
breaker.record_failure()
assert breaker.is_open
# Too early
time.sleep(0.2)
assert breaker.is_open
# After timeout
time.sleep(0.4)
assert breaker.is_half_open
def test_config_object(self):
"""Test using CircuitBreakerConfig object."""
config = CircuitBreakerConfig(
failure_threshold=7,
success_threshold=3,
timeout=120.0,
half_open_max_calls=5
)
breaker = CircuitBreaker("test", config=config)
stats = breaker.get_stats()
assert stats['config']['failure_threshold'] == 7
assert stats['config']['success_threshold'] == 3
assert stats['config']['timeout'] == 120.0
assert stats['config']['half_open_max_calls'] == 5
@pytest.mark.unit
class TestCircuitBreakerReset:
"""Test manual reset functionality."""
def test_manual_reset_from_open(self):
"""Manual reset should close circuit from OPEN state."""
breaker = CircuitBreaker("test", failure_threshold=1)
breaker.record_failure()
assert breaker.is_open
breaker.reset()
assert breaker.is_closed
def test_manual_reset_clears_counters(self):
"""Reset should clear failure and success counters."""
breaker = CircuitBreaker("test", failure_threshold=5)
breaker.record_failure()
breaker.record_failure()
breaker.record_failure()
breaker.reset()
stats = breaker.get_stats()
assert stats['failure_count'] == 0
assert stats['success_count'] == 0
assert stats['last_failure_time'] is None
@pytest.mark.unit
class TestCircuitBreakerStats:
"""Test statistics and monitoring functionality."""
def test_get_stats_returns_current_state(self):
"""get_stats() should return current circuit state."""
breaker = CircuitBreaker("test-circuit")
stats = breaker.get_stats()
assert stats['name'] == "test-circuit"
assert stats['state'] == CircuitState.CLOSED.value
assert stats['failure_count'] == 0
assert stats['success_count'] == 0
assert stats['last_failure_time'] is None
def test_get_stats_includes_failure_count(self):
"""Stats should include current failure count."""
breaker = CircuitBreaker("test", failure_threshold=5)
breaker.record_failure()
breaker.record_failure()
stats = breaker.get_stats()
assert stats['failure_count'] == 2
assert stats['last_failure_time'] is not None
def test_get_stats_includes_config(self):
"""Stats should include configuration values."""
breaker = CircuitBreaker(
"test",
failure_threshold=10,
success_threshold=3,
timeout=90.0
)
stats = breaker.get_stats()
assert stats['config']['failure_threshold'] == 10
assert stats['config']['success_threshold'] == 3
assert stats['config']['timeout'] == 90.0
@pytest.mark.unit
class TestCircuitBreakerThreadSafety:
"""Test thread safety of circuit breaker operations.
Note: These are basic tests. Full thread-safety testing would require
concurrent operations from multiple threads.
"""
def test_concurrent_check_state_safe(self):
"""Multiple check_state() calls should be safe."""
breaker = CircuitBreaker("test")
# Should not raise due to race conditions
for _ in range(100):
breaker.check_state()
def test_concurrent_record_operations_safe(self):
"""Concurrent record_success/record_failure should be safe."""
breaker = CircuitBreaker("test", failure_threshold=50)
# Simulate mixed success/failure operations
for i in range(100):
if i % 3 == 0:
breaker.record_success()
else:
breaker.record_failure()
# Should have consistent state
stats = breaker.get_stats()
assert isinstance(stats['failure_count'], int)
assert stats['state'] in [s.value for s in CircuitState]
@pytest.mark.unit
class TestCircuitBreakerEdgeCases:
"""Test edge cases and error conditions."""
def test_zero_failure_threshold_not_recommended(self):
"""Circuit with zero threshold opens on first failure."""
breaker = CircuitBreaker("test", failure_threshold=0)
assert breaker.is_closed # Starts closed
# First failure opens immediately (0 threshold)
breaker.record_failure()
assert breaker.is_open
def test_very_short_timeout(self):
"""Circuit should handle very short timeouts."""
breaker = CircuitBreaker("test", failure_threshold=1, timeout=0.01)
breaker.record_failure()
assert breaker.is_open
time.sleep(0.02)
assert breaker.is_half_open
def test_state_property_triggers_update(self):
"""Accessing .state property should trigger timeout check."""
breaker = CircuitBreaker("test", failure_threshold=1, timeout=0.1)
breaker.record_failure()
assert breaker.state == CircuitState.OPEN
time.sleep(0.15)
# Accessing state should trigger transition
assert breaker.state == CircuitState.HALF_OPEN
def test_multiple_resets_safe(self):
"""Multiple resets should be safe."""
breaker = CircuitBreaker("test")
for _ in range(10):
breaker.reset()
assert breaker.is_closed
def test_success_in_closed_with_no_failures(self):
"""Recording success when no failures is safe."""
breaker = CircuitBreaker("test")
breaker.record_success()
breaker.record_success()
assert breaker.is_closed
stats = breaker.get_stats()
assert stats['failure_count'] == 0