[Compute] Fix #34069: az vm update: Fix conflicting Capacity Reservation state transitions

[WhaleTech (ryo-whaletech)]

Related command

az vm update

Description

Fixes #34069

az vm update starts from the existing VM state before applying command-specific update arguments. When switching Capacity Reservation assignment modes, the persisted opposite state could therefore remain in the outgoing request.

This change removes only the conflicting persisted value:

• assigning a real Capacity Reservation Group removes disableCapacityReservationAssignment only when its persisted value is true;
• explicitly setting --disable-capacity-reservation-assignment true removes a persisted Capacity Reservation Group.

Valid persisted or explicit false is preserved. Omitted arguments, unrelated VM updates, the existing "None" Capacity Reservation Group disassociation behavior, and the current same-invocation validation remain unchanged.

The fix is limited to the standalone VM update customization and focused regression tests. Generated AAZ files are unchanged because they correctly serialize the state provided by the update layer.

Testing Guide

Added regression coverage for both conflicting transitions and compatibility coverage for false, omitted arguments, unrelated updates, and the "None" sentinel.

Validation:

• Regression test reproduced both conflicting transitions against the unmodified upstream implementation.
• Capacity Reservation transition matrix: 17 cases passed after the fix.
• test_custom_vm_commands.py: 9 passed.
• Relevant Capacity Reservation / generic VM update tests: 3 passed, with 1 expected live-only test skipped.
• azdev style vm: passed.
• azdev linter vm: passed.
• git diff --check: passed.

Full upstream CI remains pending on the PR.

History Notes

[Compute] az vm update: Fix conflicting Capacity Reservation state when switching assignment modes

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Thank you for your contribution WhaleTech (@ryo-whaletech)! We will review the pull request and get back to you soon.

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🟢 Approval recommended

Focused changes have regression coverage with no unresolved blocking issues.

Pull request overview

Fixes conflicting Capacity Reservation state transitions in az vm update by removing stale opposing values while preserving valid states.

Changes:

• Reconciles Capacity Reservation assignment updates.
• Adds focused transition and compatibility regression tests.

File summaries

File	Description
src/azure-cli/azure/cli/command_modules/vm/tests/latest/test_custom_vm_commands.py	Adds transition, compatibility, and validation coverage.
src/azure-cli/azure/cli/command_modules/vm/custom.py	Reconciles persisted Capacity Reservation state.

Review details

• Files reviewed: 2/2 changed files
• Comments generated: 0
• Review effort level: Lite

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[Yong Zhang (yonzhan)]

Compute