I am writing integration tests for a project in which I am making HTTP calls and testing whether they were successful or not.
Since I am not importing any module and not calling functions directly coverage.py report for this is 0%.
I want to know how can I generate coverage report for such integration HTTP request tests?
The recipe is pretty much this:
Example:
Imagine you have a dummy backend server that responds with a "Hello World" page on GET requests:
# backend.py
from http.server import BaseHTTPRequestHandler, HTTPServer
class DummyHandler(BaseHTTPRequestHandler):
def do_GET(self):
self.send_response(200)
self.send_header('Content-Type', 'text/html')
self.end_headers()
self.wfile.write('<html><body><h1>Hello World</h1></body></html>'.encode())
if __name__ == '__main__':
HTTPServer(('127.0.0.1', 8000), DummyHandler).serve_forever()
A simple test that makes an HTTP request and verifies the response contains "Hello World":
# tests/test_server.py
import requests
def test_GET():
resp = requests.get('http://127.0.0.1:8000')
resp.raise_for_status()
assert 'Hello World' in resp.text
# tests/conftest.py
import os
import signal
import subprocess
import time
import coverage.data
import pytest
@pytest.fixture(autouse=True)
def run_backend(cov):
# 1.
env = os.environ.copy()
env['COVERAGE_FILE'] = '.coverage.backend'
serverproc = subprocess.Popen(['coverage', 'run', 'backend.py'], env=env,
stdout=subprocess.PIPE,
stderr=subprocess.PIPE,
preexec_fn=os.setsid)
time.sleep(3)
yield # 2.
# 3.
serverproc.send_signal(signal.SIGINT)
time.sleep(1)
# 4.
backendcov = coverage.data.CoverageData()
with open('.coverage.backend') as fp:
backendcov.read_fileobj(fp)
cov.data.update(backendcov)
cov is the fixture provided by pytest-cov (docs).
Running the test adds the coverage of backend.py to the overall coverage, although only tests selected:
$ pytest --cov=tests --cov-report term -vs
=============================== test session starts ===============================
platform linux -- Python 3.6.5, pytest-3.4.1, py-1.5.3, pluggy-0.6.0 --
/data/gentoo64/usr/bin/python3.6
cachedir: .pytest_cache
rootdir: /data/gentoo64/home/u0_a82/projects/stackoverflow/so-50689940, inifile:
plugins: mock-1.6.3, cov-2.5.1
collected 1 item
tests/test_server.py::test_GET PASSED
----------- coverage: platform linux, python 3.6.5-final-0 -----------
Name Stmts Miss Cover
------------------------------------------
backend.py 12 0 100%
tests/conftest.py 18 0 100%
tests/test_server.py 5 0 100%
------------------------------------------
TOTAL 35 0 100%
============================ 1 passed in 5.09 seconds =============================
coverage.misc.CoverageException: Doesn't seem to be a coverage.py data file
coverage package in pytest and on backend side, related issue.
With Coverage 5.1, based on the "Measuring sub-processes" section of the coverage.py docs, you can set the COVERAGE_PROCESS_START env-var, call the coverage.process_startup() somewhere in your code. If you set parallel=True in your .coveragerc
Somewhere in your process, call this code:
import coverage
coverage.process_startup()
This can be done in sitecustomize.py globally, but in my case it was easy to add this to my application's __init__.py, where I added:
import os
if 'COVERAGE_PROCESS_START' in os.environ:
import coverage
coverage.process_startup()
Just to be safe, I added an additional check to this if statement (checking if MYAPP_COVERAGE_SUBPROCESS is also set)
In your test case, set the COVERAGE_PROCESS_START to the path to your .coveragerc file (or an empty string if don't need this config), for example:
import os
import subprocess
env = os.environ.copy()
env['COVERAGE_PROCESS_START'] = '.coveragerc'
cmd = [sys.executable, 'run_my_app.py']
p = subprocess.Popen(cmd, env=env)
p.communicate()
assert p.returncode == 0 # ..etc
Finally, you create .coveragerc containing:
[run]
parallel = True
source = myapp # Which module to collect coverage for
This ensures the .coverage files created by each process go to a unique file, which pytest-cov appears to merge automatically (or can be done manually with coverage combine). It also describes which modules to collect data for (the --cov=myapp arg doesn't get passed to child processes)
To run your tests, just invoke pytest --cov=
