action: add unit test coverage check workflow

.github/codecov.yml

@@ -0,0 +1,25 @@
+coverage:
+  status:
+    project:
+      default:
+        enabled: yes
+        target: auto  # auto compares coverage to the previous base commit
+        # adjust accordingly based on how flaky your tests are
+        # this allows a 1% drop from the previous base commit coverage
+        threshold: 1%
+    patch:
+      default:
+        target: 25%   # the required coverage value in each patch
+
+comment:
+  layout: "reach, diff, flags, files"
+  behavior: default
+  require_changes: false # if true: only post the comment if coverage changes
+
+codecov:
+  require_ci_to_pass: false
+  notify:
+    wait_for_ci: false
+
+# When modifying this file, please validate using
+# curl -X POST --data-binary @codecov.yml https://codecov.io/validate

.github/workflows/smoke.yml

@@ -141,6 +141,26 @@ jobs:
       run: |
         make ut
 
+  nydus-unit-test-coverage:
+    runs-on: ubuntu-latest
+    env:
+      CARGO_TERM_COLOR: always
+    steps:
+      - uses: actions/checkout@v3
+      - name: Rust Cache
+        uses: Swatinem/rust-cache@v2.2.0
+        with:
+          cache-on-failure: true
+      - name: Install cargo-llvm-cov
+        uses: taiki-e/install-action@cargo-llvm-cov
+      - name: Generate code coverage
+        run: make coverage-codecov
+      - name: Upload coverage to Codecov
+        uses: codecov/codecov-action@v3
+        with:
+          files: codecov.json
+          fail_ci_if_error: true
+
   nydus-cargo-deny:
     name: cargo-deny
     runs-on: ubuntu-latest

Makefile

@@ -15,6 +15,7 @@ INSTALL_DIR_PREFIX ?= "/usr/local/bin"
 DOCKER ?= "true"
 
 CARGO ?= $(shell which cargo)
+RUSTUP ?= $(shell which rustup)
 CARGO_BUILD_GEARS = -v ~/.ssh/id_rsa:/root/.ssh/id_rsa -v ~/.cargo/git:/root/.cargo/git -v ~/.cargo/registry:/root/.cargo/registry
 SUDO = $(shell which sudo)
 CARGO_COMMON ?= 
@@ -111,6 +112,19 @@ install: release
 ut: .release_version
 	TEST_WORKDIR_PREFIX=$(TEST_WORKDIR_PREFIX) RUST_BACKTRACE=1 ${CARGO} test --workspace $(EXCLUDE_PACKAGES) $(CARGO_COMMON) $(CARGO_BUILD_FLAGS) -- --skip integration --nocapture --test-threads=8
 
+# install test dependencies
+pre-coverage:
+	${CARGO} +stable install cargo-llvm-cov --locked
+	${RUSTUP} component add llvm-tools-preview
+
+# print unit test coverage to console
+coverage: pre-coverage
+	TEST_WORKDIR_PREFIX=$(TEST_WORKDIR_PREFIX) ${CARGO} llvm-cov --workspace $(EXCLUDE_PACKAGES) $(CARGO_COMMON) $(CARGO_BUILD_FLAGS) -- --skip integration --nocapture  --test-threads=8
+
+# write unit teset coverage to codecov.json, used for Github CI
+coverage-codecov:
+	TEST_WORKDIR_PREFIX=$(TEST_WORKDIR_PREFIX) ${CARGO} llvm-cov --codecov --output-path codecov.json --workspace $(EXCLUDE_PACKAGES) $(CARGO_COMMON) $(CARGO_BUILD_FLAGS) -- --skip integration --nocapture  --test-threads=8
+
 smoke-only:
 	make -C smoke test
 
@@ -214,4 +228,4 @@ docker-example: all-static-release
 	@docker exec $$cid /run.sh
 	@EXIT_CODE=$$?
 	@docker rm -f $$cid
-	@exit $$EXIT_CODE
+	@exit $$EXIT_CODE