tests: fix server_test.go

[clement2026]

#18494 creates a non-empty raft log snapshot on server startup, which requires:

1. There are available entries in raft log.
2. A non-nil kv is set :
   

   etcd/server/etcdserver/server.go

   Lines 2132 to 2143 in 981061a

   	func (s *EtcdServer) snapshot(snapi uint64, confState raftpb.ConfState) {
   	d := GetMembershipInfoInV2Format(s.Logger(), s.cluster)
   	// commit kv to write metadata (for example: consistent index) to disk.
   	//
   	// This guarantees that Backend's consistent_index is >= index of last snapshot.
   	//
   	// KV().commit() updates the consistent index in backend.
   	// All operations that update consistent index must be called sequentially
   	// from applyAll function.
   	// So KV().Commit() cannot run in parallel with toApply. It has to be called outside
   	// the go routine created below.
   	s.KV().Commit()

---

This PR fixes the failed tests in server_test.go by :

1. Appending raft log entries by sending a put request to raft.Node's readyc
2. Setting a non-nil kv for EtcdServer

---

Part of #17098

[k8s-ci-robot]

Hi @clement2026. Thanks for your PR.

I'm waiting for a etcd-io member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

I understand the commands that are listed here.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.

[codecov-commenter]

⚠️ Please install the to ensure uploads and comments are reliably processed by Codecov.

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 68.88%. Comparing base (981061a) to head (f39b328).

❗ Current head f39b328 differs from pull request most recent head 6336424

Please upload reports for the commit 6336424 to get more accurate results.

❗ Your organization needs to install the Codecov GitHub app to enable full functionality.

Additional details and impacted files

see 23 files with indirect coverage changes

@@            Coverage Diff             @@
##             main   #18582      +/-   ##
==========================================
+ Coverage   68.73%   68.88%   +0.15%     
==========================================
  Files         420      420              
  Lines       35474    35474              
==========================================
+ Hits        24382    24438      +56     
+ Misses       9666     9617      -49     
+ Partials     1426     1419       -7     

---

Continue to review full report in Codecov by Sentry.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 981061a...6336424. Read the comment docs.

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: clement2026, serathius

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [serathius]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[serathius]

cc @ahrtr

[ahrtr]

The change is simple and straightforward, but let's get #18494 (comment) clarified firstly.