caldav-server-tester

A command-line tool that probes a CalDAV server and reports which features and RFC requirements it supports, which ones it handles quirky, and which ones it gets wrong.

It is a companion to the CalDAV Python client library and produces output that is compatible with that library's compatibility_hints.py feature-flag system. See https://caldav.readthedocs.io/latest/configfile.html#testing-server-compatibility on how to use it for configuring your server compatibility in a formt that the libary can read.

What it checks

The full list is currently maintained in the CalDAV library, https://github.com/python-caldav/caldav/blob/master/caldav/compatibility_hints.py - the checks includes:

• Calendar creation and deletion (MKCALENDAR)
• Saving and loading events, tasks, and journals
• Time-range, text, alarm, and recurrence searches (RFC 4791)
• Case sensitivity and substring matching in text searches
• Sync-collection reports (RFC 6578)
• Free-busy queries
• Principal discovery (RFC 5397)
• A WWW-Authenticate header on a 401, naming a usable scheme (RFC 7235)
• Scheduling identity: whether calendar-user-address-set holds an address (RFC 6638)
• Duplicate UID handling across calendars
• Timezone support in events

For full usage information, including all CLI options and output formats, see USAGE.md.

Installation

make install

(This auto-detects uv, pipx, or pip and does the right thing. Hopefully.)

Quick example

caldav-server-tester --caldav-url https://example.com/dav \
                     --caldav-username alice \
                     --caldav-password secret

See USAGE.md for details on output formats (--format json/yaml/hints), the --diff flag, running individual checks, and safety considerations.

Roadmap

docs/ROADMAP.md describes what the tool covers today, what is funded for the next period, and what is wanted but not funded.

Background

The caldav client library accumulated a large set of compatibility flags to work around differences between CalDAV server implementations. Every server deviates from the RFC in at least some way — some silently ignore unsupported features, some return errors, some return wrong data.

This tool was created to make it easy to discover and document those deviations without having to run the full caldav test suite and interpret failures manually. It can also alert you when a previously flagged problem has been fixed in a newer server version.

Vocabulary

The project is called caldav-server-tester, but internally the word test is reserved for code under the tests/ directory. Code that probes server capability is called a check.

License

AGPL-3.0-or-later