introduce code coverage to the cpp sdk

.github/actions/gcovr/action.yaml

@@ -0,0 +1,79 @@
+name: Gcovr
+description: Generate code coverage reports with gcovr and llvm-cov
+
+inputs:
+  build-directory:
+    description: Build directory containing coverage data (.gcda / .gcno)
+    required: false
+    default: build
+  source-root:
+    description: Source root for gcovr --root
+    required: false
+    default: ${{ github.workspace }}
+  gcov-executable:
+    description: gcov executable passed to gcovr (e.g. llvm-cov-16 gcov for Clang)
+    required: false
+    default: llvm-cov-16 gcov
+  gcovr-version:
+    description: gcovr PyPI version to install
+    required: false
+    default: "8.4"
+  output-directory:
+    description: Directory for generated coverage reports
+    required: false
+    default: build/coverage
+  fail-under-line:
+    description: Fail if line coverage is below this percent (0 disables the gate)
+    required: false
+    default: "0"
+  post-pr-comment:
+    description: Post or update a sticky coverage summary on the pull request
+    required: false
+    default: "true"
+  github-token:
+    description: Token for posting PR comments
+    required: false
+    default: ${{ github.token }}
+
+runs:
+  using: composite
+  steps:
+    - name: Install gcovr
+      shell: bash
+      run: |
+        python3 -m pip install --user "gcovr==${{ inputs.gcovr-version }}"
+        echo "$HOME/.local/bin" >> "$GITHUB_PATH"
+
+    - name: Verify llvm-cov
+      shell: bash
+      run: |
+        llvm_cov="${{ inputs.gcov-executable }}"
+        llvm_cov_bin="${llvm_cov%% *}"
+        if ! command -v "${llvm_cov_bin}" >/dev/null 2>&1; then
+          echo "::error::${llvm_cov_bin} not found; install LLVM or adjust gcov-executable"
+          exit 1
+        fi
+
+    - name: Generate coverage report
+      shell: bash
+      run: |
+        chmod +x "${{ github.action_path }}/run_gcovr.sh"
+        SOURCE_ROOT="${{ inputs.source-root }}" \
+        BUILD_DIR="${{ github.workspace }}/${{ inputs.build-directory }}" \
+        OUTPUT_DIR="${{ github.workspace }}/${{ inputs.output-directory }}" \
+        GCOV_EXECUTABLE="${{ inputs.gcov-executable }}" \
+        FAIL_UNDER_LINE="${{ inputs.fail-under-line }}" \
+        "${{ github.action_path }}/run_gcovr.sh"
+
+    - name: Post coverage PR comment
+      if: inputs.post-pr-comment == 'true'
+      shell: bash
+      env:
+        GH_TOKEN: ${{ inputs.github-token }}
+        PR_NUMBER: ${{ github.event.pull_request.number }}
+        OUTPUT_DIR: ${{ github.workspace }}/${{ inputs.output-directory }}
+        GITHUB_REPOSITORY: ${{ github.repository }}
+        GITHUB_RUN_ID: ${{ github.run_id }}
+      run: |
+        chmod +x "${{ github.action_path }}/post_pr_comment.sh"
+        "${{ github.action_path }}/post_pr_comment.sh"

.github/actions/gcovr/post_pr_comment.sh

@@ -0,0 +1,100 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+: "${OUTPUT_DIR:?OUTPUT_DIR is required}"
+: "${GITHUB_REPOSITORY:?GITHUB_REPOSITORY is required}"
+: "${GITHUB_RUN_ID:?GITHUB_RUN_ID is required}"
+
+MARKER='<!-- ydb-cpp-sdk-coverage -->'
+SUMMARY_JSON="${OUTPUT_DIR}/summary.json"
+
+if [[ -z "${PR_NUMBER:-}" ]]; then
+  echo "PR_NUMBER is not set; skipping coverage PR comment"
+  exit 0
+fi
+
+if [[ ! -f "${SUMMARY_JSON}" ]]; then
+  echo "::warning::${SUMMARY_JSON} not found; skipping coverage PR comment"
+  exit 0
+fi
+
+if ! command -v gh >/dev/null 2>&1; then
+  echo "::error::gh CLI is required to post PR comments"
+  exit 1
+fi
+
+BODY="$(MARKER="${MARKER}" SUMMARY_JSON="${SUMMARY_JSON}" GITHUB_REPOSITORY="${GITHUB_REPOSITORY}" GITHUB_RUN_ID="${GITHUB_RUN_ID}" python3 <<'PY'
+import json
+import os
+from pathlib import Path
+
+marker = os.environ["MARKER"]
+summary = json.loads(Path(os.environ["SUMMARY_JSON"]).read_text())
+repo = os.environ["GITHUB_REPOSITORY"]
+run_id = os.environ["GITHUB_RUN_ID"]
+
+line = summary["line"]
+branch = summary["branch"]
+func = summary["function"]
+
+def bar(percent: float) -> str:
+    filled = max(0, min(10, int(round(percent / 10))))
+    return "█" * filled + "░" * (10 - filled)
+
+files = [
+    f for f in summary.get("files", [])
+    if f.get("line_total", 0) >= 20
+]
+files.sort(key=lambda f: f.get("line_percent") or 0)
+lowest = files[:8]
+
+run_url = f"https://github.com/{repo}/actions/runs/{run_id}"
+lines = [
+    marker,
+    "## Code coverage",
+    "",
+    f"Workflow run: [Coverage job #{run_id}]({run_url}) · download the **coverage-report** artifact for the HTML report.",
+    "",
+    "| Metric | Coverage | Covered / total |",
+    "| --- | --- | --- |",
+    f"| Line | **{line['percent']:.1f}%** {bar(line['percent'])} | {line['covered']} / {line['num']} |",
+    f"| Branch | **{branch['percent']:.1f}%** {bar(branch['percent'])} | {branch['covered']} / {branch['num']} |",
+    f"| Function | **{func['percent']:.1f}%** {bar(func['percent'])} | {func['covered']} / {func['num']} |",
+    "",
+    "Scope: `src/`, `include/ydb-cpp-sdk/`, `plugins/` (contrib, tests, and `_deps` excluded).",
+]
+
+if lowest:
+    lines.extend([
+        "",
+        "<details>",
+        "<summary>Lowest line coverage (≥ 20 lines)</summary>",
+        "",
+        "| File | Line % | Covered / total |",
+        "| --- | ---: | --- |",
+    ])
+    for f in lowest:
+        pct = f.get("line_percent") or 0
+        lines.append(
+            f"| `{f['filename']}` | {pct:.1f}% | {f['line_covered']} / {f['line_total']} |"
+        )
+    lines.extend(["", "</details>"])
+
+print("\n".join(lines))
+PY
+)"
+
+COMMENT_ID="$(gh api "repos/${GITHUB_REPOSITORY}/issues/${PR_NUMBER}/comments" \
+  --paginate \
+  --jq ".[] | select(.body | contains(\"${MARKER}\")) | .id" \
+  | head -n1)"
+
+if [[ -n "${COMMENT_ID}" ]]; then
+  gh api -X PATCH "repos/${GITHUB_REPOSITORY}/issues/comments/${COMMENT_ID}" \
+    -f body="${BODY}" >/dev/null
+  echo "Updated coverage comment ${COMMENT_ID} on PR #${PR_NUMBER}"
+else
+  gh api "repos/${GITHUB_REPOSITORY}/issues/${PR_NUMBER}/comments" \
+    -f body="${BODY}" >/dev/null
+  echo "Posted coverage comment on PR #${PR_NUMBER}"
+fi

.github/actions/gcovr/run_gcovr.sh

@@ -0,0 +1,49 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+: "${SOURCE_ROOT:?SOURCE_ROOT is required}"
+: "${BUILD_DIR:?BUILD_DIR is required}"
+: "${OUTPUT_DIR:?OUTPUT_DIR is required}"
+: "${GCOV_EXECUTABLE:=llvm-cov-16 gcov}"
+
+mkdir -p "${OUTPUT_DIR}"
+
+gcovr_args=(
+  --root "${SOURCE_ROOT}"
+  --object-directory "${BUILD_DIR}"
+  --gcov-executable "${GCOV_EXECUTABLE}"
+  --print-summary
+  --json-summary "${OUTPUT_DIR}/summary.json"
+  --html --html-details
+  -o "${OUTPUT_DIR}/index.html"
+  --cobertura "${OUTPUT_DIR}/cobertura.xml"
+  --exclude '.*contrib/.*'
+  --exclude '.*tests/.*'
+  --exclude '.*/_deps/.*'
+  --filter 'src/'
+  --filter 'include/ydb-cpp-sdk/'
+  --filter 'plugins/'
+)
+
+if [[ -n "${FAIL_UNDER_LINE:-}" && "${FAIL_UNDER_LINE}" != "0" ]]; then
+  gcovr_args+=(--fail-under-line "${FAIL_UNDER_LINE}")
+fi
+
+gcovr "${gcovr_args[@]}"
+
+if [[ -n "${GITHUB_STEP_SUMMARY:-}" && -f "${OUTPUT_DIR}/summary.json" ]]; then
+  {
+    echo "## Code coverage"
+    echo ""
+    echo "| Metric | Covered | Total | Percent |"
+    echo "| --- | ---: | ---: | ---: |"
+    jq -r '
+      .line as $l
+      | .branch as $b
+      | .function as $f
+      | "| Line | \($l.covered) | \($l.num) | \($l.percent // 0)% |",
+        "| Branch | \($b.covered) | \($b.num) | \($b.percent // 0)% |",
+        "| Function | \($f.covered) | \($f.num) | \($f.percent // 0)% |"
+    ' "${OUTPUT_DIR}/summary.json"
+  } >> "${GITHUB_STEP_SUMMARY}"
+fi

.github/workflows/coverage.yml

@@ -0,0 +1,79 @@
+name: Coverage
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+    types: [opened, synchronize, reopened, ready_for_review]
+    branches:
+      - main
+
+concurrency:
+  group: coverage-${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  coverage:
+    runs-on: ubuntu-22.04
+    permissions:
+      contents: read
+      pull-requests: write
+    services:
+      ydb:
+        image: ydbplatform/local-ydb:24.4
+        ports:
+          - 2135:2135
+          - 2136:2136
+          - 8765:8765
+        volumes:
+          - /tmp/ydb_certs:/ydb_certs
+        env:
+          YDB_LOCAL_SURVIVE_RESTART: true
+          YDB_USE_IN_MEMORY_PDISKS: true
+          YDB_TABLE_ENABLE_PREPARED_DDL: true
+        options: '-h localhost'
+    steps:
+      - name: Checkout PR
+        uses: actions/checkout@v4
+        if: github.event.pull_request.head.sha != ''
+        with:
+          submodules: true
+          ref: ${{ github.event.pull_request.head.sha }}
+
+      - name: Checkout
+        uses: actions/checkout@v4
+        if: github.event.pull_request.head.sha == ''
+        with:
+          submodules: true
+
+      - name: Install dependencies
+        uses: ./.github/actions/prepare_vm
+
+      - name: Configure and build with coverage
+        shell: bash
+        run: |
+          mkdir -p build
+          rm -rf build/*
+          cmake --preset coverage-test-gcc
+          cmake --build build -j"$(nproc)"
+
+      - name: Test
+        shell: bash
+        run: |
+          ctest -j1 --preset coverage-all --output-on-failure
+
+      - name: Generate coverage report
+        uses: ./.github/actions/gcovr
+        with:
+          build-directory: build
+          source-root: ${{ github.workspace }}
+          gcov-executable: gcov-13
+          post-pr-comment: ${{ github.event_name == 'pull_request' }}
+
+      - name: Upload coverage reports
+        uses: actions/upload-artifact@v4
+        with:
+          name: coverage-report
+          path: build/coverage/
+          retention-days: 14

CMakeLists.txt

@@ -43,6 +43,7 @@ include(CMakePackageConfigHelpers)
 list(APPEND CMAKE_MODULE_PATH ${YDB_SDK_SOURCE_DIR}/cmake)
 
 include(cmake/global_flags.cmake)
+include(cmake/coverage.cmake)
 include(cmake/global_vars.cmake)
 include(cmake/install.cmake)
 include(cmake/common.cmake)

CMakePresets.json

@@ -99,6 +99,21 @@
       "name": "debug-test-gcc",
       "inherits": ["debug-base", "gcc-toolchain", "test"],
       "displayName": "Default Debug Test Config (GCC)"
+    },
+    {
+      "name": "coverage-base",
+      "inherits": ["release-base", "test"],
+      "hidden": true,
+      "cacheVariables": {
+        "YDB_SDK_COVERAGE": "ON",
+        "ARCADIA_ROOT": "${sourceDir}",
+        "ARCADIA_BUILD_ROOT": "${sourceDir}/build"
+      }
+    },
+    {
+      "name": "coverage-test-gcc",
+      "inherits": ["coverage-base", "gcc-toolchain"],
+      "displayName": "Coverage Test Config (GCC)"
     }
   ],
   "buildPresets": [
@@ -154,6 +169,25 @@
         "YDB_ENDPOINT": "localhost:2136",
         "YDB_DATABASE": "/local"
       }
+    },
+    {
+      "name": "coverage-all",
+      "inherits": "all",
+      "displayName": "Run All Tests (coverage CI)",
+      "configurePreset": "coverage-test-gcc",
+      "execution": {
+        "timeout": 1800
+      },
+      "filter": {
+        "exclude": {
+          "name": "(ManyMessages|DiscoveryHang|DescribeHang)"
+        }
+      },
+      "environment": {
+        "YDB_ENDPOINT": "localhost:2136",
+        "YDB_DATABASE": "/local",
+        "YDB_VERSION": "24.4"
+      }
     }
   ]
 }

cmake/ccache.cmake

@@ -1,5 +1,7 @@
 find_program(CCACHE_PATH ccache)
-if (NOT CCACHE_PATH)
+if (YDB_SDK_COVERAGE)
+  message(STATUS "YDB_SDK_COVERAGE is ON: ccache compiler launchers disabled")
+elseif (NOT CCACHE_PATH)
   message(AUTHOR_WARNING
     "Ccache is not found, that will increase the re-compilation time; "
     "pass -DCCACHE_PATH=path/to/bin to specify the path to the `ccache` binary file."

cmake/common.cmake

@@ -201,6 +201,7 @@ function(_ydb_sdk_add_library Tgt)
   target_compile_definitions(${Tgt} ${includeMode}
     YDB_SDK_OSS
   )
+  _ydb_sdk_apply_coverage(${Tgt})
 endfunction()
 
 function(_ydb_sdk_validate_public_headers)