Drop a filter that matched nothing, keep the 79 ports it hid, and exit on a value the registers should not hold

data-import/httpmethod.py

@@ -3,13 +3,14 @@
 
     data-import/httpmethod.py [--source URL_OR_FILE] [--cache DIR] [--out FILE]
 
-A method whose name is not letters and hyphens does not ship, which drops the `*` the
-registry holds to stop anyone registering it.
+A row needs a name of letters and hyphens, which drops the registry's `*`, and both of
+the answers the registry gives for it.
 """
 import argparse
 import csv
 import io
 import re
+import sys
 from pathlib import Path
 
 import source
@@ -19,13 +20,19 @@ SOURCE = "https://www.iana.org/assignments/http-methods/methods.csv"
 OUT = Path(__file__).resolve().parent.parent / "data" / "misc" / "httpmethod.tsv"
 CACHE = Path(__file__).resolve().parent / "cache"
 COLUMNS = ["idempotent", "method", "safe"]
+ANSWERS = ("yes", "no")
 
 
 def rows(text):
     for r in csv.DictReader(io.StringIO(text)):
-        method, safe, idempotent = r["Method Name"].strip(), r["Safe"].strip(), r["Idempotent"].strip()
-        if re.match(r"^[A-Za-z][A-Za-z-]*$", method) and safe and idempotent:
-            yield {"idempotent": idempotent, "method": method, "safe": safe}
+        method = (r["Method Name"] or "").strip()
+        safe, idempotent = (r["Safe"] or "").strip(), (r["Idempotent"] or "").strip()
+        if not re.fullmatch(r"[A-Za-z][A-Za-z-]*", method) or not safe or not idempotent:
+            continue
+        for column, answer in (("Safe", safe), ("Idempotent", idempotent)):
+            if answer not in ANSWERS:
+                sys.exit(f"{method}: {column} {answer!r} is neither yes nor no")
+        yield {"idempotent": idempotent, "method": method, "safe": safe}
 
 
 def main():