In the Transactions spec unified test, we get this error because we allow a read preference of secondary to be supplied to the default transaction options:

[2024/02/12 13:40:07.660]   6) Transactions Spec Unified Tests
[2024/02/12 13:40:07.660]        transaction-options
[2024/02/12 13:40:07.660]          readPreference inherited from defaultTransactionOptions:
[2024/02/12 13:40:07.660]      AssertionError: Operation find succeeded but was not supposed to
[2024/02/12 13:40:07.660]       at executeOperationAndCheck (test/tools/unified-spec-runner/operations.ts:932:12)
[2024/02/12 13:40:07.660]       at processTicksAndRejections (node:internal/process/task_queues:95:5)
[2024/02/12 13:40:07.660]       at async runUnifiedTest (test/tools/unified-spec-runner/runner.ts:197:9)
[2024/02/12 13:40:07.660]       at async Context.<anonymous> (test/tools/unified-spec-runner/runner.ts:288:11)

Use Case

As a... Node.js Driver User
I want... (what is the desired change)
So that... (why is the change desired)

User Impact

• Small

Dependencies

• N/A

Unknowns

• How to figure out when a read operation is attempted within a transaction? (Spec says we only throw this error when a read is attempted, not when the transaction is created)
  • Solution: Create CommandisReadOperation boolean helper
  • e.g. command.find || command.count || command.aggregate || command.distinct
  • ^^ Unsure if these are all the read operations, will confirm in kickoff

Acceptance Criteria

Implementation Requirements

• The driver currently always sets the read preference to primary, it needs to be updated to raise an error if not.

• • The spec states: If a read is attempted and the transaction’s read preference is not Primary drivers MUST raise an error containing the string "read preference in a transaction must be primary"

Testing Requirements

• Unskip transactions unified spec test marked with TODO(NODE-5925)

Documentation Requirements

• Change Node.js Transactions readPreference page to reflect the fact that we currently only support primary as the readPreference for transactions

Follow Up Requirements

• N/A