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How to Mock a Metrics Decorator in Python with unittest.mock
This code demonstrates a timing decorator that wraps a function to measure execution time and prints the duration, with a unit test using unittest.mock to patch the print function and assert it was called.
import time
from functools import wraps
from unittest.mock import patch
def add_metrics(func):
@wraps(func)
def wrapper(*args, **kwargs):
start = time.perf_counter()
result = func(*args, **kwargs)
elapsed = time.perf_counter() - start
print(f"{func.__name__} took {elapsed:.6f}s…How to Mock a Timeout per Dependency Call in Python
This code demonstrates how to simulate and test per-call timeouts for external dependencies using Python's unittest.mock and a simple timing wrapper.
```python
import time
from unittest.mock import Mock, patch
def call_dependency(dependency, timeout):
start = time.time()
result = dependency.call()
elapsed = time.time() - start
if elapsed > timeout:
raise TimeoutError(f"Dependency call took {elapsed:.2f}s, exceeding timeout {timeout}s")
…Mock Unit of Work commit and rollback in Python
Verify that a Unit of Work pattern commits on success and rolls back on failure using unittest.mock in Python.
from unittest import mock
class UnitOfWork:
def __init__(self):
self.committed = False
self.rolled_back = False
def commit(self):
self.committed = True
print("Commit executed")
def rollback(self):
self.rolled_back = True
print("Rollback executed")
def b…How to Mock Offset Commit Auto vs Manual in Python
Demonstrates a Kafka-style offset commit function with auto/manual modes and tests it using unittest.mock.patch.
from unittest.mock import Mock, patch
def commit_offsets(topic_partition_offsets, auto_commit=False):
"""Manually commit offsets or simulate auto-commit."""
if auto_commit:
print(f"Auto-committing offsets: {topic_partition_offsets}")
return {"status": "auto_committed"}
print(f"Manuall…How to Mock Cache Tag Invalidation in Python
Use unittest.mock.patch with wraps to verify tagged cache entries are invalidated correctly.
import unittest
from unittest.mock import patch
def get_cached_data(cache, key):
"""Return data from cache if present and valid, else None."""
if cache.get(key, {}).get("valid", False):
return cache[key]["data"]
return None
def invalidate_tag_mock(cache, tag):
"""Invalidate all cache entries …How to Mock a Cache Key Schema Version Bump in Python
Show how to test a cache key schema bump by mocking the class-level version attribute with unittest.mock.
from unittest import mock
class VersionCache:
SCHEMA_VERSION = 1
def __init__(self, key_prefix="cache"):
self.key_prefix = key_prefix
def build_key(self, resource_id):
return f"{self.key_prefix}:schema-v{self.SCHEMA_VERSION}:{resource_id}"
def bump_schema(self):
# Simulated …How to Mock a Timeout per HTTP Request in Python
Simulate a per-request HTTP timeout using unittest.mock to test timeout handling without network access.
import time
from unittest.mock import Mock, patch
# Simulate an HTTP client that might time out
def fetch_data(url, timeout=5):
time.sleep(0.5) # Simulate network delay
return f"Response from {url}"
# Mock to test timeout behavior without real network
def test_timeout():
mock_response = Mock(side_effect…How to retry idempotent operations with a mock in Python
Wrap a flaky idempotent operation in a retry loop with exponential backoff, and use unittest.mock to deterministically test the str's behavior.
import random
import time
from unittest.mock import Mock
def idempotent_operation(value):
"""Simulate an idempotent operation that sometimes fails."""
if random.random() < 0.6: # 60% failure rate
raise ConnectionError("Temporary failure")
return value * 2
def retry_with_backoff(operation, max_…Mocking a Metrics Gauge's set_value Method in Python
Demonstrates using unittest.mock.Mock with wraps to intercept a gauge's set_value call while verifying arguments and preserving real behavior.
from unittest.mock import Mock
class MetricsGauge:
def __init__(self, name):
self.name = name
self.value = 0.0
def set_value(self, new_value):
self.value = float(new_value)
return self.value
# Usage demonstration with a mock
gauge = MetricsGauge("cpu_usage")
gauge_mock = Mock…How to Mock Hive Support in PySpark with unittest.mock
This code demonstrates how to mock Hive support in a PySpark environment using unittest.mock to simulate SQL queries returning fixed data.
from unittest.mock import Mock, patch
def get_hive_tables(spark):
"""Mock Hive support by returning a fixed list of tables."""
return spark.sql("SHOW TABLES").collect()
class HiveTable:
"""Simple class that mimics a Hive table row."""
def __init__(self, database, tableName):
self.database =…How to Mock a Compute-Collect Action Trigger in Python
Mock a compute-collect action trigger using Python's unittest.mock to simulate Spark-style job execution and assert trigger behavior.
Here's a Python code sample for the problem title "Action trigger compute collect mock":How to Mock MLflow log_params and log_metrics in Python
Use unittest.mock to patch MLflow's log_param and log_metric, run the training function, and verify logging calls without touching a real tracking server.
from unittest.mock import Mock, patch
import mlflow
def train_model():
mlflow.log_param("learning_rate", 0.01)
mlflow.log_param("epochs", 10)
mlflow.log_metric("accuracy", 0.95)
mlflow.log_metric("loss", 0.05)
return "Training completed"
if __name__ == "__main__":
with patch("mlflow.log_par…How to Create a Sticky Consistent Mock with unittest.mock in Python
Shows how to use unittest.mock.patch.object to mock a method consistently across multiple calls, returning a sticky value every time.
from unittest.mock import patch
class Database:
def fetch(self, key):
return f"real value for {key}"
def get_value(db, key):
return db.fetch(key)
if __name__ == "__main__":
db = Database()
with patch.object(db, "fetch", return_value="sticky value") as mock_fetch:
result1 = get_value(…How to Mock Sequential Calls in Python with unittest.mock
Use Mock.side_effect to return a different result for each sequential call and verify the call order with assert_has_calls.
import unittest
from unittest.mock import Mock
class Service:
def fetch(self, item_id):
raise NotImplementedError
def process_items(service, ids):
results = []
for item_id in ids:
result = service.fetch(item_id)
results.append(result)
return results
if __name__ == "__main__":…How to Mock Time for Cache TTL Testing in Python
This code demonstrates how to test a cache's TTL expiration logic by mocking time.time with unittest.mock to control the passage of time.
import time
from unittest.mock import patch
class ConfigCache:
def __init__(self, ttl=60):
self.ttl = ttl
self._store = {}
self._timestamps = {}
def get(self, key):
if key not in self._store:
return None
if time.time() - self._timestamps[key] > self.ttl:
…How to Mock a Function Call in Python with unittest.mock
Use unittest.mock.Mock to wrap a function and spy on its call count and arguments in Python.
import random
from unittest.mock import Mock, patch
def select_n_plus_one(numbers: list[int]) -> int:
"""Return the first number that appears more than once, if any."""
seen = set()
for num in numbers:
if num in seen:
return num
seen.add(num)
return -1
def detect_mock(se…How to Mock Environment Variables in Python for 12-Factor Config
Read 12-factor config from env vars and test/mock them with unittest.mock.patch.dict without touching the real environment.
import os
import json
from unittest.mock import patch
def load_config(env_prefix="APP"):
"""Read 12-factor style config from env vars"""
required = ["DATABASE_URL", "API_KEY"]
optional = {"PORT": "8080", "DEBUG": "false"}
config = {}
for key in required:
full_key = f"{env_prefix}_{key…How to Mock HTTP Responses to Verify HSTS Headers in Python
This code demonstrates how to use unittest.mock to intercept and capture HTTP response headers, specifically the Strict-Transport-Security header, from a mocked HTTPServer handler for security validation.
from http.server import BaseHTTPRequestHandler, HTTPServer
from unittest.mock import patch
class StrictTransportMock(BaseHTTPRequestHandler):
def do_GET(self):
self.send_response(200)
self.send_header("Strict-Transport-Security", "max-age=31536000; includeSubDomains")
self.end_headers()
…How to Mock Kubernetes Secret Mounts in Python
Create and inspect a mock Kubernetes secret volume mount using the official client library and unittest.mock.
import json
from kubernetes import client, config, watch
from unittest.mock import Mock, patch
def create_mock_mount_spec():
"""Create a mock Kubernetes secret volume mount."""
mock_client = Mock()
mock_client.api_version = "v1"
mock_client.kind = "Secret"
mock_client.metadata = {"name": "my-secre…How to Mock a Dependency for Readiness Probe in Python
Use unittest.mock.Mock to simulate a dependency's readiness check response for testing a service's is_ready method without hitting a real connection.
import time
import unittest
from unittest.mock import Mock
class Service:
def __init__(self, dependency):
self.dependency = dependency
def is_ready(self):
try:
result = self.dependency.check()
return result == "ready"
except Exception:
return False
…How to Smoke Test a Deployment in Python with unittest.mock
Run a post-deploy smoke test by mocking the deployment status check to verify your health-check logic returns PASS/FAIL.
import unittest
from unittest.mock import Mock, patch
class DeploymentService:
def check_status(self):
return "unknown"
def smoke_test_deploy():
service = DeploymentService()
with patch.object(service, "check_status", return_value="healthy") as mock_check:
status = service.check_status()
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