Implemented phase 5 for the POC prototype in the Website service.

Services/Website/Tests/Browser/links.py

@@ -0,0 +1,58 @@
+"""Crawls every internal link of a locally running Website — signed out, as a buyer, and as a seller — and reports the ones that fail.
+
+    swift run Website &
+    python3 Tests/Browser/links.py
+
+Stdlib only. Exits non-zero when a link answers 4xx or 5xx.
+"""
+import html, re, sys, urllib.error, urllib.parse, urllib.request
+
+BASE = "http://localhost:8080"
+
+class NoRedirect(urllib.request.HTTPRedirectHandler):
+    def redirect_request(self, *args, **kwargs):
+        return None
+
+opener = urllib.request.build_opener(NoRedirect)
+
+def fetch(path, cookie=None, data=None):
+    request = urllib.request.Request(BASE + path, data=data, headers={"Cookie": cookie} if cookie else {})
+    try:
+        response = opener.open(request)
+    except urllib.error.HTTPError as error:
+        response = error
+    return response.status, response.headers, response.read().decode("utf-8", "replace")
+
+def sign_in(email):
+    _, headers, _ = fetch("/sign-in", data=urllib.parse.urlencode({"email": email, "return": "/"}).encode())
+    return headers["Set-Cookie"].split(";")[0]
+
+def crawl(name, cookie):
+    seen, queue, broken = set(), ["/"], []
+    while queue:
+        path = queue.pop()
+        if path in seen:
+            continue
+        seen.add(path)
+        status, headers, body = fetch(path, cookie)
+        if status >= 400:
+            broken.append((status, path))
+            continue
+        if 300 <= status < 400:
+            target = urllib.parse.urlsplit(headers["Location"])
+            queue.append(target.path + ("?" + target.query if target.query else ""))
+            continue
+        for href in re.findall(r'href="(/[^"#]*)', body):
+            href = html.unescape(href)
+            # Assets are covered by the app's own tests; the crawl is for screens.
+            if not re.match(r"/(css|js|font|uploads)/|/[^/]+\.(ico|svg|png|webmanifest|xml|txt)", href):
+                queue.append(href)
+    print(f"{name}: {len(seen)} links, {len(broken)} broken")
+    for status, path in sorted(broken):
+        print(f"  {status}  {path}")
+    return broken
+
+broken = crawl("signed out", None)
+broken += crawl("buyer", sign_in(""))
+broken += crawl("seller", sign_in("joost@kestrelrow.example"))
+sys.exit(1 if broken else 0)