CI: add code coverage action

.github/workflows/build.yml

@@ -37,7 +37,17 @@ jobs:
             ${{ runner.os }}-buildx-
 
       - name: Unit test
-        run: go test ./...
+        run: go test -v -short ./pkg/... ./cmd/... -coverprofile cover.out
+
+      - name: Publish Unit Test Coverage
+        uses: codecov/codecov-action@v3
+        with:
+          name: codecov-umbrella
+          token: ${{ secrets.CODECOV_TOKEN }}
+          flags: unittests
+          files: ./cover.out
+          fail_ci_if_error: true
+          verbose: true
 
       - name: Docker meta
         id: meta

README.md

@@ -1,5 +1,13 @@
 # Raven
 
+<div align="left">
+
+[![Go Report Card](https://goreportcard.com/badge/github.com/openyurtio/raven)](https://goreportcard.com/report/github.com/openyurtio/raven)
+[![License](https://img.shields.io/badge/license-Apache%202-4EB1BA.svg)](https://www.apache.org/licenses/LICENSE-2.0.html)
+[![codecov](https://codecov.io/gh/openyurtio/raven/branch/main/graph/badge.svg)](https://codecov.io/gh/openyurtio/raven)
+
+</div>
+
 Raven is component of the OpenYurt to enhance cluster networking capabilities. This enhancement is focused on edge-edge and edge-cloud communication in OpenYurt. In short, it will provide layer 3 network connectivity among pods in different physical regions, as there are in one vanilla Kubernetes cluster.
 
 ## Architecture