housekeep: define filters in their own modules

This patch cleans up aurweb.templates and removes direct
module-level initialization of the environment.

Signed-off-by: Kevin Morris <kevr@0cost.org>

test/test_filters.py

@@ -0,0 +1,36 @@
+from datetime import datetime
+from zoneinfo import ZoneInfo
+
+from aurweb import filters
+
+
+def test_timestamp_to_datetime():
+    ts = datetime.utcnow().timestamp()
+    dt = datetime.utcfromtimestamp(int(ts))
+    assert filters.timestamp_to_datetime(ts) == dt
+
+
+def test_as_timezone():
+    ts = datetime.utcnow().timestamp()
+    dt = filters.timestamp_to_datetime(ts)
+    assert filters.as_timezone(dt, "UTC") == dt.astimezone(tz=ZoneInfo("UTC"))
+
+
+def test_number_format():
+    assert filters.number_format(0.222, 2) == "0.22"
+    assert filters.number_format(0.226, 2) == "0.23"
+
+
+def test_extend_query():
+    """ Test extension of a query via extend_query. """
+    query = {"a": "b"}
+    extended = filters.extend_query(query, ("a", "c"), ("b", "d"))
+    assert extended.get("a") == "c"
+    assert extended.get("b") == "d"
+
+
+def test_to_qs():
+    """ Test conversion from a query dictionary to a query string. """
+    query = {"a": "b", "c": [1, 2, 3]}
+    qs = filters.to_qs(query)
+    assert qs == "a=b&c=1&c=2&c=3"