refactor(ast): add test coverage workflow

Change-Id: Ie9234a0998f7c424672cd8dffca44fe0d406148d

Author: Ggiggle

.github/workflows/ci.yaml

@@ -19,6 +19,7 @@ jobs:
       - test-macos
       - test-windows
       - lint
+      - coverage
     steps:
       - run: exit 0
 
@@ -98,3 +99,36 @@ jobs:
       - name: Format check
         run: |
           cargo fmt -- --check
+
+    cov:
+    runs-on: ubuntu-latest
+    timeout-minutes: 40
+    permissions:
+      contents: read
+      checks: write
+      pull-requests: write
+
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@stable
+      - uses: taiki-e/install-action@v2
+        with:
+          tool: cargo-llvm-cov
+
+      - name: Generate coverage (LCOV + HTML)
+        run: |
+          cargo llvm-cov --workspace --all-features --doctests \
+            --lcov --output-path lcov.info
+          cargo llvm-cov --workspace --all-features --doctests --html
+
+      - uses: actions/upload-artifact@v4
+        with:
+          name: coverage-html
+          path: target/llvm-cov/html
+
+      - name: Upload to Codecov
+        uses: codecov/codecov-action@v4
+        with:
+          files: lcov.info
+          fail_ci_if_error: true
+          verbose: true

.github/workflows/cov.yaml

@@ -0,0 +1,10 @@
+coverage:
+  status:
+    project:                 # 可选：总覆盖率门禁（想只卡 patch 也行）
+      default:
+        informational: true  # 仅展示，不卡死 CI（想卡就设 false 并配 target）
+    patch:
+      default:
+        target: 70%          # 新增/修改的 diff 区域覆盖率必须 ≥ 70%
+        threshold: 0%        # 不允许低于目标（留有回旋可设 2% 之类）
+        informational: false # 失败时让检查变红，阻止合并（配合分支保护）