Add coverage steps to the GitHub action (#10)

.github/workflows/go.yml

@@ -7,8 +7,7 @@ on:
     branches: [ main ]
 
 jobs:
-
-  build:
+  build-test-coverage:
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v2
@@ -28,3 +27,14 @@ jobs:
 
     - name: Test
       run: go1.18beta1 test -v ./...
+
+    - name: Calcualte coverage
+      run: |
+        go1.18beta1 test -v -covermode=count -coverprofile=coverage.out
+    - name: Convert coverage.out to coverage.lcov
+      uses: jandelgado/gcov2lcov-action@v1.0.6
+    - name: Coveralls
+      uses: coverallsapp/github-action@v1.1.2
+      with:
+        github-token: ${{ secrets.github_token }}
+        path-to-lcov: coverage.lcov

README.md

@@ -1,6 +1,7 @@
 # go-tuple: Generic tuples for Go 1.18.
 
 [![Go](https://github.com/barweiss/go-tuple/actions/workflows/go.yml/badge.svg)](https://github.com/barweiss/go-tuple/actions/workflows/go.yml)
+[![Coverage Status](https://coveralls.io/repos/github/barweiss/go-tuple/badge.svg)](https://coveralls.io/github/barweiss/go-tuple)
 
 Go 1.18 tuple implementation.