test_app_v1.py

"""Example usage of pytest fixtures."""

import subprocess
import re

import pytest
import requests


class App:
    """Manages starting and stopping my app for testing."""

    def __init__(self, port=None):
        self.proc = None
        self.listen_addr = None
        self._port = port

    def start(self):
        """
        Start my app in a subprocess. Extracts the listening address from the
        stdout - necessary because the app binds to port 0.
        """
        # Ensure app binary is built first.
        subprocess.run(["go", "build"], check=True)
        cmd = ["./app"]
        if self._port is not None:
            cmd.extend(["-port", str(self._port)])
            
        self.proc = subprocess.Popen(cmd, stdout=subprocess.PIPE, text=True)
        stdout_line = self.proc.stdout.readline()
        match = re.match(r"listening on (.*)", stdout_line)
        if not match:
            self.proc.terminate()
            raise RuntimeError(
                f"Could not extract listen address from stdout: {stdout_line}"
            )
        self.listen_addr = match.group(1)

    def stop(self):
        """Stop the app by sending SIGTERM."""
        if not self.proc:
            raise RuntimeError("No process to stop")
        self.proc.terminate()
        self.proc.wait()


def test_app():
    """Test making an HTTP request to my app."""
    app = App()
    app.start()

    rsp = requests.get(f"{app.listen_addr}/hello")
    assert rsp.status_code == 200
    assert rsp.text == 'Hello, "/hello"'

    app.stop()