add codecov report

.github/workflows/go.yml

@@ -27,4 +27,4 @@ jobs:
         go get -v -t -d ./...
 
     - name: Test
-      run: go test -v -race ./...
+      run: go test -race -coverprofile=coverage.txt -covermode=atomic ./...

.travis.yml

@@ -0,0 +1,13 @@
+language: go
+
+go:
+  - 1.14.x
+
+before_install:
+  - go get -t -v ./...
+
+script:
+  - go test -race -coverprofile=coverage.txt -covermode=atomic
+
+after_success:
+  - bash <(curl -s https://codecov.io/bash)