Remove Facebook fbclid tracking query param

tildes/tests/test_url_transform.py

@@ -48,6 +48,14 @@ def test_other_mobile_subdomain_not_removed():
     assert cleaned_url == url
 
 
+def test_facebook_tracking_removed():
+    """Ensure that Facebook's "click tracking" query param is removed."""
+    url = "https://example.com/?fbclid=qwertyuiopasdfghjkl"
+    cleaned_url = apply_url_transformations(url)
+
+    assert cleaned_url == "https://example.com/"
+
+
 def test_reddit_tracking_removed():
     """Ensure that Reddit's "share tracking" query params are removed."""
     url = "https://www.reddit.com/r/tildes/comments/8k14is/_/?sort=new&st=abcdefgh&sh=1234asd"

tildes/tildes/lib/url_transform.py

@@ -156,6 +156,19 @@ class TwitterMobileConverter(UrlTransformer):
         return parsed_url._replace(netloc="twitter.com")
 
 
+class FacebookTrackingRemover(UrlTransformer):
+    """Remove Facebook's "click tracking" query parameter (fbclid)."""
+
+    @classmethod
+    def apply_transformation(cls, parsed_url: ParseResult) -> ParseResult:
+        """Apply the actual transformation process to the url."""
+        query_params = parse_qs(parsed_url.query, keep_blank_values=True)
+
+        query_params.pop("fbclid", None)
+
+        return parsed_url._replace(query=urlencode(query_params, doseq=True))
+
+
 class RedditTrackingRemover(UrlTransformer):
     """Remove Reddit's "share tracking" query parameters (st and sh)."""