Dockerfile

@@ -8,7 +8,7 @@ ENV PYTHONDONTWRITEBYTECODE=1 \
     SNACK_AND_LIFT_E2E=1
 
 RUN apt-get update \
-    && apt-get install -y --no-install-recommends chromium chromium-driver fonts-liberation \
+    && apt-get install -y --no-install-recommends chromium chromium-driver fonts-liberation fonts-noto-color-emoji \
     && rm -rf /var/lib/apt/lists/*
 
 WORKDIR /app

README.md

@@ -75,6 +75,24 @@ Leave the environment with `deactivate`. The folder `.venv` is ignored by git.
 
 ## ▶️ Run
 
+### Your gym account
+
+The bot never contains a password. Register your own account once, by hand, as the lecture does: run the bot with `--keep-open` so Chrome stays open (the `chrome_profile` folder keeps the site's data between runs), click "Join Today... Or Tomorrow" and register with an e-mail such as `yourname@test.com` and a password you remember (not a trivial one such as `12346`, Chrome warns about those). Then give the bot the account through two environment variables:
+
+```bash
+# Linux and macOS
+export SNACK_AND_LIFT_EMAIL="yourname@test.com"
+export SNACK_AND_LIFT_PASSWORD="your password"
+```
+
+```powershell
+# Windows PowerShell
+$env:SNACK_AND_LIFT_EMAIL = "yourname@test.com"
+$env:SNACK_AND_LIFT_PASSWORD = "your password"
+```
+
+### Start the bot
+
 With the environment active:
 
 ```bash

pyproject.toml

@@ -29,7 +29,7 @@ where = ["src"]
 [tool.pytest.ini_options]
 testpaths = ["tests"]
 addopts = "-ra --strict-markers"
-pythonpath = ["src"]
+pythonpath = ["src", "."]
 markers = [
     "browser: needs a real browser (run in the Docker container)",
 ]

src/snack_and_lift/application/credentials.py

@@ -0,0 +1,35 @@
+"""@file credentials.py
+@brief The account the bot logs in with, read from the environment (never from the code).
+"""
+
+from collections.abc import Mapping
+from dataclasses import dataclass, field
+
+from snack_and_lift import constants
+from snack_and_lift.domain.errors import MissingCredentialsError
+
+
+@dataclass(frozen=True, slots=True)
+class Credentials:
+    """@brief E-mail and password of the gym account; the password is never printed."""
+
+    email: str
+    password: str = field(repr=False)
+
+
+def load_credentials(environment: Mapping[str, str]) -> Credentials:
+    """@brief Read the account from the environment.
+
+    @param environment The environment variables, for example `os.environ`.
+    @return The credentials.
+    @exception MissingCredentialsError A variable is missing or empty; the message names
+        the variables and never a value.
+    """
+    email = environment.get(constants.ACCOUNT_EMAIL_ENV, "").strip()
+    password = environment.get(constants.ACCOUNT_PASSWORD_ENV, "")
+    if not email or not password:
+        raise MissingCredentialsError(
+            f"Set {constants.ACCOUNT_EMAIL_ENV} and {constants.ACCOUNT_PASSWORD_ENV} "
+            "in the environment (they must not be empty)"
+        )
+    return Credentials(email=email, password=password)

src/snack_and_lift/application/ports.py

@@ -0,0 +1,38 @@
+"""@file ports.py
+@brief The ports the use cases need from the outside world.
+"""
+
+from pathlib import Path
+from typing import Protocol
+
+
+class GymPort(Protocol):
+    """@brief The gym site as the use cases see it."""
+
+    def open_site(self) -> None:
+        """@brief Open the home page and wait until it is ready.
+
+        @exception GymError The page did not load.
+        """
+        ...
+
+    def log_in(self, email: str, password: str) -> None:
+        """@brief Log in and wait until the class schedule is shown.
+
+        @param email The account e-mail.
+        @param password The account password.
+        @exception LoginFailedError The site refused the login.
+        @exception GymError The page did not behave as expected.
+        """
+        ...
+
+    def save_screenshot(self, path: Path) -> None:
+        """@brief Save a screenshot of the current page.
+
+        @param path The PNG file to write; its folders are created.
+        """
+        ...
+
+    def close(self) -> None:
+        """@brief Close the browser."""
+        ...

src/snack_and_lift/application/session.py

@@ -0,0 +1,21 @@
+"""@file session.py
+@brief Lecture step 2: the login of the bot.
+"""
+
+import logging
+
+from snack_and_lift.application.credentials import Credentials
+from snack_and_lift.application.ports import GymPort
+
+logger = logging.getLogger(__name__)
+
+
+def login(gym: GymPort, credentials: Credentials) -> None:
+    """@brief Log in and wait until the class schedule is shown.
+
+    @param gym The gym site.
+    @param credentials The account to log in with.
+    @exception LoginFailedError The login failed; `retry` repeats it (lecture step 9).
+    """
+    gym.log_in(credentials.email, credentials.password)
+    logger.info("✓ Logged in: the class schedule is shown")

src/snack_and_lift/cli.py

@@ -4,16 +4,40 @@
 
 import argparse
 import logging
-from collections.abc import Sequence
+import os
+import sys
+from collections.abc import Callable, Sequence
+from pathlib import Path
+
+from snack_and_lift.application.credentials import load_credentials
+from snack_and_lift.application.ports import GymPort
+from snack_and_lift.application.session import login
+from snack_and_lift.domain.errors import LoginFailedError, MissingCredentialsError
+from snack_and_lift.infrastructure.browser import create_driver, default_profile_dir
+from snack_and_lift.infrastructure.selenium_gym import SeleniumGym
+
+## Builds the gym site from (headless, profile folder, keep open).
+GymFactory = Callable[[bool, Path, bool], GymPort]
 
 logger = logging.getLogger(__name__)
 
 
+def selenium_gym_factory(headless: bool, profile_dir: Path, keep_open: bool) -> GymPort:
+    """@brief Start Chrome and wrap it as the gym site.
+
+    @param headless True to run without a window.
+    @param profile_dir The Chrome user data folder.
+    @param keep_open True to leave the browser open when the program ends.
+    @return The gym site.
+    """
+    return SeleniumGym(create_driver(headless, profile_dir, keep_open))
+
+
 def parse_args(argv: Sequence[str] | None = None) -> argparse.Namespace:
     """@brief Read the command line.
 
     @param argv Arguments without the program name; None reads `sys.argv`.
-    @return The parsed options.
+    @return The parsed options; `keep_open` is True unless `--headless` is given.
     """
     parser = argparse.ArgumentParser(
         prog="snack-and-lift",
@@ -24,16 +48,78 @@ def parse_args(argv: Sequence[str] | None = None) -> argparse.Namespace:
         action="store_true",
         help="run Chrome without a window (the Docker image does this)",
     )
-    return parser.parse_args(argv)
+    parser.add_argument(
+        "--keep-open",
+        action="store_true",
+        default=None,
+        help="leave the browser open at the end (default when not headless)",
+    )
+    parser.add_argument(
+        "--profile-dir",
+        type=Path,
+        default=None,
+        help="Chrome profile folder (default: ./chrome_profile)",
+    )
+    parser.add_argument(
+        "--screenshot-dir",
+        type=Path,
+        default=None,
+        help="save a screenshot after each step into this folder",
+    )
+    args = parser.parse_args(argv)
+    if args.keep_open is None:
+        args.keep_open = not args.headless
+    if args.profile_dir is None:
+        args.profile_dir = default_profile_dir()
+    return args
 
 
-def main(argv: Sequence[str] | None = None) -> int:
+def _use_utf8_output() -> None:
-    """@brief Start the bot.
+    """@brief Make stdout UTF-8 so the check mark of the messages prints on Windows."""
+    reconfigure = getattr(sys.stdout, "reconfigure", None)
+    if reconfigure is not None:
+        reconfigure(encoding="utf-8")
+
+
+def _save_step(gym: GymPort, screenshot_dir: Path | None, name: str) -> None:
+    """@brief Save a screenshot when a folder was asked for.
+
+    @param gym The gym site.
+    @param screenshot_dir The folder, or None for no screenshots.
+    @param name The file name.
+    """
+    if screenshot_dir is not None:
+        gym.save_screenshot(screenshot_dir / name)
+
+
+def main(
+    argv: Sequence[str] | None = None,
+    gym_factory: GymFactory = selenium_gym_factory,
+) -> int:
+    """@brief Start the bot: open the site and log in.
 
     @param argv Arguments without the program name; None reads `sys.argv`.
-    @return Process exit code.
+    @param gym_factory Builds the gym site; tests pass a fake.
+    @return Process exit code: 0 done, 1 login failed, 2 credentials missing.
     """
     logging.basicConfig(level=logging.INFO, format="%(message)s")
-    parse_args(argv)
+    _use_utf8_output()
-    logger.info("snack-and-lift: the lecture steps are added by the next milestones")
+    args = parse_args(argv)
+    try:
+        credentials = load_credentials(os.environ)
+    except MissingCredentialsError as error:
+        logger.error("%s", error)
+        return 2
+    gym = gym_factory(args.headless, args.profile_dir, args.keep_open)
+    try:
+        gym.open_site()
+        _save_step(gym, args.screenshot_dir, "step-1.png")
+        login(gym, credentials)
+        _save_step(gym, args.screenshot_dir, "step-2.png")
+    except LoginFailedError as error:
+        logger.error("Login failed: %s", error)
+        return 1
+    finally:
+        if not args.keep_open:
+            gym.close()
     return 0

src/snack_and_lift/constants.py

@@ -24,6 +24,27 @@ TARGET_WEEKDAYS: Final[tuple[str, ...]] = ("Tue", "Thu")
 ## Id of the login button in the navigation bar of the site (the home page has no title).
 NAV_LOGIN_BUTTON_ID: Final[str] = "login-button"
 
+## Id of the e-mail field of the login form.
+LOGIN_EMAIL_INPUT_ID: Final[str] = "email-input"
+
+## Id of the password field of the login form.
+LOGIN_PASSWORD_INPUT_ID: Final[str] = "password-input"
+
+## Id of the submit button of the login form.
+LOGIN_SUBMIT_BUTTON_ID: Final[str] = "submit-button"
+
+## Id of the element that shows a login error.
+ERROR_MESSAGE_ID: Final[str] = "error-message"
+
+## Id of the class schedule page, shown after a successful login.
+SCHEDULE_PAGE_ID: Final[str] = "schedule-page"
+
+## Name of the environment variable that holds the account e-mail.
+ACCOUNT_EMAIL_ENV: Final[str] = "SNACK_AND_LIFT_EMAIL"
+
+## Name of the environment variable that holds the account password.
+ACCOUNT_PASSWORD_ENV: Final[str] = "SNACK_AND_LIFT_PASSWORD"
+
 ## Folder where screenshots of a container run are written.
 SCREENSHOT_DIR: Final[str] = "docs/images"
 

src/snack_and_lift/domain/errors.py

@@ -0,0 +1,15 @@
+"""@file errors.py
+@brief The errors of the bot.
+"""
+
+
+class GymError(Exception):
+    """@brief The gym site did not behave as the bot expected (a page, element or timeout)."""
+
+
+class LoginFailedError(GymError):
+    """@brief The site refused the login; the message is the text the site shows."""
+
+
+class MissingCredentialsError(Exception):
+    """@brief The account e-mail or password is not set in the environment."""

src/snack_and_lift/infrastructure/browser.py

@@ -1,8 +1,9 @@
 """@file browser.py
-@brief Creates the Chrome driver, headless when asked.
+@brief Creates the Chrome driver with a persistent profile, headless when asked.
 """
 
 import os
+from pathlib import Path
 
 from selenium import webdriver
 from selenium.webdriver.chrome.options import Options
@@ -11,23 +12,49 @@ from selenium.webdriver.chrome.service import Service
 from snack_and_lift import constants
 
 
-def create_driver(headless: bool) -> webdriver.Chrome:
+def default_profile_dir() -> Path:
-    """@brief Start Chrome.
+    """@brief The folder where Chrome keeps the profile of the bot.
 
-    The binary and the driver come from `CHROME_BIN` and `CHROMEDRIVER_PATH` when
+    @return `chrome_profile` below the working directory.
-    these are set (the Docker image sets them); otherwise Selenium finds them.
+    """
+    return Path.cwd() / constants.PROFILE_DIR_NAME
+
+
+def build_options(headless: bool, profile_dir: Path, keep_open: bool) -> Options:
+    """@brief Build the Chrome options (no browser is started).
 
     @param headless True to run without a window, as in the Docker container.
-    @return A running Chrome driver.
+    @param profile_dir The Chrome user data folder.
+    @param keep_open True to leave the browser open when the program ends.
+    @return The options.
     """
     options = Options()
+    options.add_argument(f"--user-data-dir={profile_dir}")
     options.add_argument(f"--window-size={constants.WINDOW_SIZE}")
+    if keep_open:
+        options.add_experimental_option("detach", True)
     if headless:
         for argument in constants.HEADLESS_BROWSER_ARGUMENTS:
             options.add_argument(argument)
     binary = os.environ.get(constants.CHROME_BIN_ENV)
     if binary:
         options.binary_location = binary
+    return options
+
+
+def create_driver(headless: bool, profile_dir: Path, keep_open: bool) -> webdriver.Chrome:
+    """@brief Start Chrome.
+
+    The binary and the driver come from `CHROME_BIN` and `CHROMEDRIVER_PATH` when
+    these are set (the Docker image sets them); otherwise Selenium finds them.
+
+    @param headless True to run without a window, as in the Docker container.
+    @param profile_dir The Chrome user data folder; it is created when missing.
+    @param keep_open True to leave the browser open when the program ends.
+    @return A running Chrome driver.
+    """
+    profile_dir.mkdir(parents=True, exist_ok=True)
+    options = build_options(headless, profile_dir, keep_open)
     driver_path = os.environ.get(constants.CHROMEDRIVER_PATH_ENV)
     service = Service(executable_path=driver_path) if driver_path else Service()
     return webdriver.Chrome(service=service, options=options)

src/snack_and_lift/infrastructure/selenium_gym.py

@@ -0,0 +1,111 @@
+"""@file selenium_gym.py
+@brief The Selenium adapter of the GymPort.
+"""
+
+import functools
+import logging
+from collections.abc import Callable
+from pathlib import Path
+from typing import Concatenate
+
+from selenium.common.exceptions import (
+    ElementClickInterceptedException,
+    NoSuchElementException,
+    StaleElementReferenceException,
+    TimeoutException,
+)
+from selenium.webdriver.common.by import By
+from selenium.webdriver.remote.webdriver import WebDriver
+from selenium.webdriver.support import expected_conditions as ec
+from selenium.webdriver.support.ui import WebDriverWait
+
+from snack_and_lift import constants
+from snack_and_lift.domain.errors import GymError, LoginFailedError
+
+logger = logging.getLogger(__name__)
+
+_SELENIUM_ERRORS = (
+    TimeoutException,
+    NoSuchElementException,
+    StaleElementReferenceException,
+    ElementClickInterceptedException,
+)
+
+
+def _translate_errors[S, **P, R](
+    method: Callable[Concatenate[S, P], R],
+) -> Callable[Concatenate[S, P], R]:
+    """@brief Turn Selenium errors of a method into GymError.
+
+    @param method The adapter method to wrap.
+    @return The wrapped method.
+    """
+
+    @functools.wraps(method)
+    def wrapper(self: S, *args: P.args, **kwargs: P.kwargs) -> R:
+        try:
+            return method(self, *args, **kwargs)
+        except _SELENIUM_ERRORS as error:
+            raise GymError(f"{method.__name__} failed: {type(error).__name__}") from error
+
+    return wrapper
+
+
+class SeleniumGym:
+    """@brief The gym site driven by a Selenium WebDriver."""
+
+    def __init__(self, driver: WebDriver, base_url: str = constants.GYM_URL) -> None:
+        """@brief Wrap a driver.
+
+        @param driver A running WebDriver.
+        @param base_url The address of the home page.
+        """
+        self._driver = driver
+        self._base_url = base_url
+        self._wait = WebDriverWait(driver, constants.WAIT_TIMEOUT_SECONDS)
+
+    @_translate_errors
+    def open_site(self) -> None:
+        """@brief Open the home page and wait for the login button.
+
+        @exception GymError The page did not load.
+        """
+        self._driver.get(self._base_url)
+        self._wait.until(ec.presence_of_element_located((By.ID, constants.NAV_LOGIN_BUTTON_ID)))
+
+    @_translate_errors
+    def log_in(self, email: str, password: str) -> None:
+        """@brief Fill in the login form and wait for the schedule or an error.
+
+        @param email The account e-mail.
+        @param password The account password.
+        @exception LoginFailedError The site shows a login error.
+        @exception GymError The page did not behave as expected.
+        """
+        self._wait.until(ec.element_to_be_clickable((By.ID, constants.NAV_LOGIN_BUTTON_ID))).click()
+        self._wait.until(
+            ec.presence_of_element_located((By.ID, constants.LOGIN_EMAIL_INPUT_ID))
+        ).send_keys(email)
+        self._driver.find_element(By.ID, constants.LOGIN_PASSWORD_INPUT_ID).send_keys(password)
+        self._driver.find_element(By.ID, constants.LOGIN_SUBMIT_BUTTON_ID).click()
+        self._wait.until(
+            ec.any_of(
+                ec.presence_of_element_located((By.ID, constants.SCHEDULE_PAGE_ID)),
+                ec.presence_of_element_located((By.ID, constants.ERROR_MESSAGE_ID)),
+            )
+        )
+        errors = self._driver.find_elements(By.ID, constants.ERROR_MESSAGE_ID)
+        if errors:
+            raise LoginFailedError(errors[0].text)
+
+    def save_screenshot(self, path: Path) -> None:
+        """@brief Save a screenshot of the current page.
+
+        @param path The PNG file to write; its folders are created.
+        """
+        path.parent.mkdir(parents=True, exist_ok=True)
+        self._driver.save_screenshot(str(path))
+
+    def close(self) -> None:
+        """@brief Quit the browser."""
+        self._driver.quit()

tests/e2e/fixtures/home.html

@@ -0,0 +1,7 @@
+<!DOCTYPE html>
+<html lang="en">
+<head><meta charset="utf-8"><title>Fixture gym home</title></head>
+<body>
+  <nav><a href="login.html"><button id="login-button">Login</button></a></nav>
+</body>
+</html>

tests/e2e/fixtures/login.html

@@ -0,0 +1,28 @@
+<!DOCTYPE html>
+<html lang="en">
+<head><meta charset="utf-8"><title>Fixture gym login</title></head>
+<body>
+  <form id="login-form">
+    <input id="email-input" type="email">
+    <input id="password-input" type="password">
+    <button id="submit-button" type="submit">Log in</button>
+  </form>
+  <div id="message-area"></div>
+  <script>
+    // Dummy account of this fixture only; it is not a real account.
+    const ACCEPTED_EMAIL = "fixture@example.invalid";
+    const ACCEPTED_PASSWORD = "fixture-password";
+    document.getElementById("login-form").addEventListener("submit", function (event) {
+      event.preventDefault();
+      const email = document.getElementById("email-input").value;
+      const password = document.getElementById("password-input").value;
+      if (email === ACCEPTED_EMAIL && password === ACCEPTED_PASSWORD) {
+        window.location.href = "schedule.html";
+      } else {
+        document.getElementById("message-area").innerHTML =
+          '<div id="error-message">Invalid email or password</div>';
+      }
+    });
+  </script>
+</body>
+</html>

tests/e2e/fixtures/schedule.html

@@ -0,0 +1,7 @@
+<!DOCTYPE html>
+<html lang="en">
+<head><meta charset="utf-8"><title>Fixture gym schedule</title></head>
+<body>
+  <div id="schedule-page">Class schedule</div>
+</body>
+</html>

tests/e2e/test_browser_smoke.py

@@ -3,6 +3,8 @@
 """
 
 import os
+import tempfile
+from pathlib import Path
 
 import pytest
 from selenium.webdriver.common.by import By
@@ -22,7 +24,7 @@ pytestmark = [
 
 
 def test_gym_home_page_shows_the_login_button() -> None:
-    driver = create_driver(headless=True)
+    driver = create_driver(headless=True, profile_dir=Path(tempfile.mkdtemp()), keep_open=False)
     try:
         driver.get(constants.GYM_URL)
         button = WebDriverWait(driver, constants.WAIT_TIMEOUT_SECONDS).until(

tests/e2e/test_selenium_gym.py

@@ -0,0 +1,57 @@
+"""@file test_selenium_gym.py
+@brief The Selenium adapter against local HTML fixtures; runs only in the Docker container.
+"""
+
+import os
+from collections.abc import Iterator
+from pathlib import Path
+
+import pytest
+
+from snack_and_lift.domain.errors import LoginFailedError
+from snack_and_lift.infrastructure.browser import create_driver
+from snack_and_lift.infrastructure.selenium_gym import SeleniumGym
+
+pytestmark = [
+    pytest.mark.browser,
+    pytest.mark.skipif(
+        os.environ.get("SNACK_AND_LIFT_E2E") != "1",
+        reason="needs a real browser; run it in the Docker container",
+    ),
+]
+
+FIXTURE_HOME = (Path(__file__).parent / "fixtures" / "home.html").as_uri()
+# Dummy account that the fixture login.html accepts; it is not a real account.
+FIXTURE_EMAIL = "fixture@example.invalid"
+FIXTURE_PASSWORD = "fixture-password"
+
+
+@pytest.fixture
+def gym(tmp_path: Path) -> Iterator[SeleniumGym]:
+    driver = create_driver(headless=True, profile_dir=tmp_path / "profile", keep_open=False)
+    try:
+        yield SeleniumGym(driver, base_url=FIXTURE_HOME)
+    finally:
+        driver.quit()
+
+
+def test_log_in_succeeds_with_accepted_credentials(gym: SeleniumGym) -> None:
+    gym.open_site()
+
+    gym.log_in(FIXTURE_EMAIL, FIXTURE_PASSWORD)
+
+
+def test_log_in_raises_for_wrong_credentials(gym: SeleniumGym) -> None:
+    gym.open_site()
+
+    with pytest.raises(LoginFailedError, match="Invalid"):
+        gym.log_in(FIXTURE_EMAIL, "wrong-password")
+
+
+def test_save_screenshot_creates_the_folder(gym: SeleniumGym, tmp_path: Path) -> None:
+    gym.open_site()
+    target = tmp_path / "shots" / "step-1.png"
+
+    gym.save_screenshot(target)
+
+    assert target.stat().st_size > 0

tests/unit/fakes.py

@@ -0,0 +1,35 @@
+"""@file fakes.py
+@brief A fake of the GymPort for the unit tests.
+"""
+
+from pathlib import Path
+
+from snack_and_lift.domain.errors import LoginFailedError
+
+
+class FakeGym:
+    """@brief Records the calls; can be told to refuse the login."""
+
+    def __init__(self, login_error: str | None = None) -> None:
+        self.login_error = login_error
+        self.calls: list[str] = []
+        self.logins: list[tuple[str, str]] = []
+        self.screenshots: list[Path] = []
+        self.closed = False
+
+    def open_site(self) -> None:
+        self.calls.append("open_site")
+
+    def log_in(self, email: str, password: str) -> None:
+        self.calls.append("log_in")
+        self.logins.append((email, password))
+        if self.login_error is not None:
+            raise LoginFailedError(self.login_error)
+
+    def save_screenshot(self, path: Path) -> None:
+        self.calls.append("save_screenshot")
+        self.screenshots.append(path)
+
+    def close(self) -> None:
+        self.calls.append("close")
+        self.closed = True

tests/unit/test_browser_options.py

@@ -0,0 +1,50 @@
+"""@file test_browser_options.py
+@brief The Chrome options are built correctly (no browser is started).
+"""
+
+from pathlib import Path
+
+import pytest
+
+from snack_and_lift import constants
+from snack_and_lift.infrastructure.browser import build_options, default_profile_dir
+
+
+def test_profile_dir_is_passed_to_chrome(tmp_path: Path) -> None:
+    options = build_options(False, tmp_path, False)
+
+    assert f"--user-data-dir={tmp_path}" in options.arguments
+
+
+def test_default_profile_dir_is_below_the_working_directory() -> None:
+    assert default_profile_dir() == Path.cwd() / constants.PROFILE_DIR_NAME
+
+
+def test_keep_open_detaches_the_browser(tmp_path: Path) -> None:
+    assert build_options(False, tmp_path, True).experimental_options["detach"] is True
+
+
+def test_browser_is_not_detached_when_not_kept_open(tmp_path: Path) -> None:
+    assert "detach" not in build_options(False, tmp_path, False).experimental_options
+
+
+def test_headless_adds_the_headless_arguments(tmp_path: Path) -> None:
+    options = build_options(True, tmp_path, False)
+
+    for argument in constants.HEADLESS_BROWSER_ARGUMENTS:
+        assert argument in options.arguments
+
+
+def test_window_has_no_headless_arguments_by_default(tmp_path: Path) -> None:
+    options = build_options(False, tmp_path, False)
+
+    assert "--headless=new" not in options.arguments
+    assert f"--window-size={constants.WINDOW_SIZE}" in options.arguments
+
+
+def test_chrome_binary_comes_from_the_environment(
+    monkeypatch: pytest.MonkeyPatch, tmp_path: Path
+) -> None:
+    monkeypatch.setenv(constants.CHROME_BIN_ENV, "/opt/chrome")
+
+    assert build_options(False, tmp_path, False).binary_location == "/opt/chrome"

tests/unit/test_cli.py

@@ -1,8 +1,24 @@
 """@file test_cli.py
-@brief The command line accepts its options and the entry point returns 0.
+@brief The command line accepts its options and the entry point wires the use case.
 """
 
+from pathlib import Path
+
+import pytest
+from tests.unit.fakes import FakeGym
+
+from snack_and_lift import constants
 from snack_and_lift.cli import main, parse_args
+from snack_and_lift.infrastructure.browser import default_profile_dir
+
+DUMMY_EMAIL = "dummy@example.invalid"
+DUMMY_PASSWORD = "dummy-password"
+
+
+@pytest.fixture
+def credentials_env(monkeypatch: pytest.MonkeyPatch) -> None:
+    monkeypatch.setenv(constants.ACCOUNT_EMAIL_ENV, DUMMY_EMAIL)
+    monkeypatch.setenv(constants.ACCOUNT_PASSWORD_ENV, DUMMY_PASSWORD)
 
 
 def test_headless_is_off_by_default() -> None:
@@ -13,5 +29,96 @@ def test_headless_flag_is_read() -> None:
     assert parse_args(["--headless"]).headless is True
 
 
-def test_main_returns_zero() -> None:
+def test_browser_stays_open_by_default_when_not_headless() -> None:
-    assert main([]) == 0
+    assert parse_args([]).keep_open is True
+
+
+def test_browser_is_closed_by_default_when_headless() -> None:
+    assert parse_args(["--headless"]).keep_open is False
+
+
+def test_keep_open_flag_overrides_headless_default() -> None:
+    assert parse_args(["--headless", "--keep-open"]).keep_open is True
+
+
+def test_profile_dir_defaults_to_working_directory() -> None:
+    assert parse_args([]).profile_dir == default_profile_dir()
+
+
+def test_profile_dir_option_is_read(tmp_path: Path) -> None:
+    assert parse_args(["--profile-dir", str(tmp_path)]).profile_dir == tmp_path
+
+
+def test_screenshot_dir_is_optional() -> None:
+    assert parse_args([]).screenshot_dir is None
+
+
+@pytest.mark.usefixtures("credentials_env")
+def test_main_saves_both_screenshots_on_success(tmp_path: Path) -> None:
+    gym = FakeGym()
+
+    code = main(["--screenshot-dir", str(tmp_path)], lambda *_: gym)
+
+    assert code == 0
+    assert gym.logins == [(DUMMY_EMAIL, DUMMY_PASSWORD)]
+    assert gym.screenshots == [tmp_path / "step-1.png", tmp_path / "step-2.png"]
+    assert gym.calls == ["open_site", "save_screenshot", "log_in", "save_screenshot"]
+
+
+@pytest.mark.usefixtures("credentials_env")
+def test_main_saves_no_screenshot_without_directory() -> None:
+    gym = FakeGym()
+
+    assert main([], lambda *_: gym) == 0
+    assert gym.screenshots == []
+
+
+def test_main_returns_2_when_credentials_are_missing(
+    monkeypatch: pytest.MonkeyPatch, caplog: pytest.LogCaptureFixture
+) -> None:
+    monkeypatch.delenv(constants.ACCOUNT_EMAIL_ENV, raising=False)
+    monkeypatch.delenv(constants.ACCOUNT_PASSWORD_ENV, raising=False)
+    gym = FakeGym()
+
+    code = main([], lambda *_: gym)
+
+    assert code == 2
+    assert gym.calls == []
+    assert constants.ACCOUNT_EMAIL_ENV in caplog.text
+
+
+@pytest.mark.usefixtures("credentials_env")
+def test_main_returns_1_when_login_fails() -> None:
+    gym = FakeGym(login_error="Invalid credentials")
+
+    assert main(["--headless"], lambda *_: gym) == 1
+    assert gym.closed is True
+
+
+@pytest.mark.usefixtures("credentials_env")
+def test_main_closes_the_gym_when_not_kept_open() -> None:
+    gym = FakeGym()
+
+    assert main(["--headless"], lambda *_: gym) == 0
+    assert gym.closed is True
+
+
+@pytest.mark.usefixtures("credentials_env")
+def test_main_keeps_the_gym_open_when_asked() -> None:
+    gym = FakeGym()
+
+    assert main([], lambda *_: gym) == 0
+    assert gym.closed is False
+
+
+@pytest.mark.usefixtures("credentials_env")
+def test_main_passes_options_to_the_factory(tmp_path: Path) -> None:
+    received: list[tuple[bool, Path, bool]] = []
+
+    def factory(headless: bool, profile_dir: Path, keep_open: bool) -> FakeGym:
+        received.append((headless, profile_dir, keep_open))
+        return FakeGym()
+
+    main(["--headless", "--profile-dir", str(tmp_path)], factory)
+
+    assert received == [(True, tmp_path, False)]

tests/unit/test_constants.py

@@ -9,6 +9,20 @@ def test_gym_address_is_https() -> None:
     assert constants.GYM_URL.startswith("https://")
 
 
+def test_credentials_are_read_from_named_environment_variables() -> None:
+    assert constants.ACCOUNT_EMAIL_ENV == "SNACK_AND_LIFT_EMAIL"
+    assert constants.ACCOUNT_PASSWORD_ENV == "SNACK_AND_LIFT_PASSWORD"
+
+
+def test_login_element_ids() -> None:
+    assert constants.NAV_LOGIN_BUTTON_ID == "login-button"
+    assert constants.LOGIN_EMAIL_INPUT_ID == "email-input"
+    assert constants.LOGIN_PASSWORD_INPUT_ID == "password-input"
+    assert constants.LOGIN_SUBMIT_BUTTON_ID == "submit-button"
+    assert constants.ERROR_MESSAGE_ID == "error-message"
+    assert constants.SCHEDULE_PAGE_ID == "schedule-page"
+
+
 def test_retry_count_is_seven() -> None:
     assert constants.RETRY_COUNT == 7
 

tests/unit/test_credentials.py

@@ -0,0 +1,44 @@
+"""@file test_credentials.py
+@brief Credentials come from the environment and never show the password.
+"""
+
+import pytest
+
+from snack_and_lift import constants
+from snack_and_lift.application.credentials import Credentials, load_credentials
+from snack_and_lift.domain.errors import MissingCredentialsError
+
+DUMMY_PASSWORD = "dummy-secret-value"
+
+
+def test_load_credentials_reads_both_variables() -> None:
+    environment = {
+        constants.ACCOUNT_EMAIL_ENV: "dummy@example.invalid",
+        constants.ACCOUNT_PASSWORD_ENV: DUMMY_PASSWORD,
+    }
+
+    assert load_credentials(environment) == Credentials("dummy@example.invalid", DUMMY_PASSWORD)
+
+
+@pytest.mark.parametrize(
+    "environment",
+    [
+        {},
+        {constants.ACCOUNT_EMAIL_ENV: "dummy@example.invalid"},
+        {constants.ACCOUNT_PASSWORD_ENV: DUMMY_PASSWORD},
+        {constants.ACCOUNT_EMAIL_ENV: "", constants.ACCOUNT_PASSWORD_ENV: DUMMY_PASSWORD},
+        {constants.ACCOUNT_EMAIL_ENV: "dummy@example.invalid", constants.ACCOUNT_PASSWORD_ENV: ""},
+    ],
+)
+def test_load_credentials_rejects_missing_or_empty(environment: dict[str, str]) -> None:
+    with pytest.raises(MissingCredentialsError) as caught:
+        load_credentials(environment)
+
+    message = str(caught.value)
+    assert constants.ACCOUNT_EMAIL_ENV in message
+    assert constants.ACCOUNT_PASSWORD_ENV in message
+    assert DUMMY_PASSWORD not in message
+
+
+def test_repr_hides_the_password() -> None:
+    assert DUMMY_PASSWORD not in repr(Credentials("dummy@example.invalid", DUMMY_PASSWORD))

tests/unit/test_session.py

@@ -0,0 +1,27 @@
+"""@file test_session.py
+@brief The login use case hands the credentials to the gym site.
+"""
+
+import pytest
+from tests.unit.fakes import FakeGym
+
+from snack_and_lift.application.credentials import Credentials
+from snack_and_lift.application.session import login
+from snack_and_lift.domain.errors import LoginFailedError
+
+CREDENTIALS = Credentials("dummy@example.invalid", "dummy-password")
+
+
+def test_login_passes_the_credentials_to_the_gym() -> None:
+    gym = FakeGym()
+
+    login(gym, CREDENTIALS)
+
+    assert gym.logins == [("dummy@example.invalid", "dummy-password")]
+
+
+def test_login_propagates_a_refused_login() -> None:
+    gym = FakeGym(login_error="Invalid credentials")
+
+    with pytest.raises(LoginFailedError, match="Invalid credentials"):
+        login(gym, CREDENTIALS)