At this time there is no official formal compliance test suite for OpenDocument. But there's at least one informal test suite, results are already being posted based on running that suite, and the formula group's work can be used as a test suite for spreadsheets.
This page describes information related to OpenDocument compliance testing. Please note that in general these are not formally sanctioned by OASIS (or any other standards body); these links are simply provided as useful information.
University of Central Florida
The Networking and Mobile Computing Laboratory at the School of EECS of University of Central Florida, in cooperation with Intel corporation, is working to create an extensive set of OpenDocument sample documents. They've already created a test suite. Their main page is here: http://netmoc.cpe.ucf.edu/Projects/OpenDocument/TestSuite.html
Email messages explaining/discussing this test suite are here:
In particular, note the email dated May 17, 2006 from lboloni at eecs.ucf.edu (Lotzi Boloni). He makes an important clarification that this NOT just a test from any one application: "You are right that the dangers of the exclusive use of the OpenOffice. The technique we are using is that even if the test was originally created in OpenOffice, we are unzipping the document file, manually removing all the OpenOffice specific metadata, verify if it conforms to the standard and then reassemble it. For many of the tests however, they are simply written from scratch in XML. So for all purposes, these tests can be considered as 'hand written XML based on the specification'."
Formula Test Spreadsheet
The University of Central Florida suite doesn't include a spreadsheet. Instead, the formula subcommittee's specification is specifically written so that a test suite CAN be generated from the specification. The draft specification defines three main groups (Small, Medium, and Large) and exactly what it takes to comply with each group. Here's how to download the test suite generator, which can then process the spec and create a test suite based on the current version of the specification: http://wiki.oasis-open.org/office/Test_Suite_Generator The About OpenFormula page gives more information about OpenFormula.
The OpenDocument Fellowship (not the same as the OpenDocument Foundation) maintains a list of OpenDocument-implementing applications. They use a compact version of the University of Central Florida test suite (above) to test applications, and post results on their website. See here for their list of applications and test results, as well as links to their compact version: http://www.opendocumentfellowship.com/applications
General Compliance Test Issues
A very good write-up on compliance testing issues in general is here: http://www.consortiuminfo.org/cb/
These two W3C specification give guidelines on how to specify conformance when designing a specification: