chore: add coverage report targets to Makefile

[drmingdrmer]

Changelog

chore: add coverage report targets to Makefile

Add cargo-llvm-cov to the setup target and two new targets for
generating code coverage reports using cargo llvm-cov nextest.

Changes:

• Add coverage target for terminal summary output
• Add coverage-html target that writes target/llvm-cov/html/index.html
• Install cargo-llvm-cov via make setup

Example:

make coverage       # print coverage summary
make coverage-html  # open target/llvm-cov/html/index.html in browser

test: strip proposed_at_ms from SeqV meta before struct comparison

The server sets proposed_at_ms (a wall-clock timestamp) in KvMeta
on every write — both upsert_kv and TxnOp::put. Comparing
pb::SeqV or databend_meta_types::SeqV against a literal with
meta: None therefore always fails at runtime even though seq and data
are correct.

Fix by normalizing the actual response before asserting: clone the
outer struct (TxnPutResponse / TxnDeleteResponse) and strip meta
from any embedded SeqV using struct-update syntax
(pb::SeqV { meta: None, ..v }). The same normalization is applied to
get_kv() results via .map(|v| SeqV { meta: None, ..v }).

test: add comprehensive tests for KvTransaction gRPC endpoint

Adds 17 new integration tests covering all operations in the
KvTransaction gRPC API: Put, Get, Delete, DeleteByPrefix,
FetchIncreaseU64, and PutSequential. Tests verify exact response
values using single struct comparisons rather than field-by-field
assertions, matching the test assertion style rule added to CLAUDE.md.

Changes:

• Test Put with/without match_seq, new key, and response shape
• Test Get on existing and missing keys
• Test Delete with matching/mismatching seq; verify prev_value is
  populated even on failed deletes
• Test DeleteByPrefix response count field
• Test FetchIncreaseU64: from zero, accumulation, floor (max_value),
  fetch_max_u64, and match_seq match/mismatch
• Test PutSequential: key format, seq numbering, unique key generation
• Test branch predicates: AND, OR, keys_with_prefix, multi-branch
  fallthrough, and no-match case
• Use assert_eq!(*resp, pb::SomeType { ... }) for full struct
  comparison instead of asserting individual fields separately

test: add comprehensive tests for Applier state machine logic

The applier module had no dedicated test coverage. These 41 tests
exercise every public and internal code path: entry type dispatch
(Blank/Membership/Normal), all Cmd variants (AddNode, RemoveNode,
SetFeature, UpsertKV, Transaction, KvTransaction), branch selection
with first-match-wins semantics, recursive predicate evaluation
(And/Or short-circuit, vacuous truth), condition evaluation against
Seq/Value/KeysWithPrefix operands, all six compare operators, and
every operation type (Get, Put, Delete, DeleteByPrefix,
FetchIncreaseU64, PutSequential) including match_seq guard paths.

Key design choice: tests call a.commit() before verifying via
sm.get_maybe_expired_kv() because the applier writes to an
in-memory view that only becomes visible to the SMV003 after commit.

---

• Improvement
• Build/Testing/CI

[xp-trumpet]

@xp-trumpet reviewed 4 files and all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on drmingdrmer).

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[Copilot]

Pull request overview

This PR adds code coverage reporting capabilities to the Makefile and introduces comprehensive test coverage for the KvTransaction gRPC endpoint and the Applier state machine logic. The tests use a meta-stripping approach to handle non-deterministic proposed_at_ms timestamps in SeqV comparisons.

Changes:

• Added cargo-llvm-cov installation and coverage report targets to Makefile
• Added 17 new integration tests for KvTransaction gRPC endpoint covering all operations (Put, Get, Delete, DeleteByPrefix, FetchIncreaseU64, PutSequential) and predicate logic
• Added 41 new unit tests for Applier state machine covering entry type dispatch, all Cmd variants, branch selection, predicate evaluation, and operation execution

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
Makefile	Added cargo-llvm-cov to setup target and two new coverage targets (coverage and coverage-html)
crates/server/service/tests/it/grpc/metasrv_grpc_kv_transaction.rs	Added 17 comprehensive integration tests for KvTransaction gRPC endpoint with SeqV meta normalization
crates/server/raft-store/src/applier/mod.rs	Added conditional module declaration for applier_test
crates/server/raft-store/src/applier/applier_test.rs	New file with 41 unit tests covering all Applier state machine code paths

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[xp-trumpet]

@xp-trumpet reviewed 3 files and all commit messages.
Reviewable status: all files reviewed, 3 unresolved discussions (waiting on drmingdrmer).

[Copilot]

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated no new comments.

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