Background

We have recently identified multiple bugs caused by incorrect handling of cluster parameter changes during upgrade/downgrade flows, e.g. SERVER-117012. These issues tend to surface only when FCV changes and binaries are replaced, making them hard to catch with existing test coverage.

Goal

Add a multi-version test that verifies that setClusterParameter behaves correctly for all cluster parameters across a full upgrade and downgrade cycle, including binary replacement.

Scope & Requirements

• The test should enumerate all cluster parameters that exist in the binary under test.
  • For each cluster parameter:
    • Exercise setClusterParameter before, during (if applicable), and after upgrade/downgrade.
    • Assert that parameter values are preserved or transformed correctly according to expected FCV and binary semantics.
    • Verify that no unexpected fields appear in config.clusterParameters and that older binaries do not crash or reject the configuration.

• For cluster parameters that are structs, the test must verify all nested fields:
  • Ensure each nested field can be set and read back correctly.
  • Ensure new nested fields added in later versions are handled correctly when downgrading (e.g. removed or ignored as appropriate), and do not cause crashes or validation failures.

• We suggest using the multi-cluster test utilities in multi_cluster.js to orchestrate the upgrade/downgrade process.