Add test coverage reporting and Codecov badge

.github/workflows/build.yml

@@ -37,3 +37,9 @@ jobs:
 
       - name: Test
         run: make test
+
+      - name: Upload to Codecov
+        uses: codecov/codecov-action@v4
+        with:
+          files: coverage.txt
+          token: ${{ secrets.CODECOV_TOKEN }}

Makefile

@@ -14,6 +14,7 @@ test: testdeps
 	    go test ./... -short -race && \
 	    go test ./... -run=NONE -bench=. -benchmem && \
 	    env GOOS=linux GOARCH=386 go test && \
+	    go test -coverprofile=coverage.txt -covermode=atomic ./... && \
 	    go vet); \
 	done
 	cd internal/customvet && go build .

README.md

@@ -3,6 +3,7 @@
 [![build workflow](https://github.com/redis/go-redis/actions/workflows/build.yml/badge.svg)](https://github.com/redis/go-redis/actions)
 [![PkgGoDev](https://pkg.go.dev/badge/github.com/redis/go-redis/v9)](https://pkg.go.dev/github.com/redis/go-redis/v9?tab=doc)
 [![Documentation](https://img.shields.io/badge/redis-documentation-informational)](https://redis.uptrace.dev/)
+[![codecov](https://codecov.io/github/redis/go-redis/graph/badge.svg?token=tsrCZKuSSw)](https://codecov.io/github/redis/go-redis)
 [![Chat](https://discordapp.com/api/guilds/752070105847955518/widget.png)](https://discord.gg/rWtp5Aj)
 
 > go-redis is brought to you by :star: [**uptrace/uptrace**](https://github.com/uptrace/uptrace).