feat: add test coverage comment (#802)

* generate test coverage in CI

* add test coverage as comment in PR

Author: marceljk

.github/workflows/ci.yaml

@@ -1,6 +1,15 @@
 name: CI
 
-on: [pull_request, workflow_dispatch]
+on:
+  pull_request:
+  workflow_dispatch:
+  push:
+    branches:
+      - main
+
+env:
+  CODE_COVERAGE_FILE_NAME: "coverage.out" # must be the same as in Makefile
+  CODE_COVERAGE_ARTIFACT_NAME: "code-coverage"
 
 jobs:
   main:
@@ -26,8 +35,15 @@ jobs:
       - name: Test
         run: make test
 
+      - name: Archive code coverage results
+        uses: actions/upload-artifact@v4
+        with:
+          name: ${{ env.CODE_COVERAGE_ARTIFACT_NAME }}
+          path: ${{ env.CODE_COVERAGE_FILE_NAME }}
+
   config:
     name: Check GoReleaser config
+    if: github.event_name == 'pull_request'
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
@@ -36,4 +52,19 @@ jobs:
       - name: Check GoReleaser
         uses: goreleaser/goreleaser-action@v6
         with:
-          args: check
+          args: check
+
+  code_coverage:
+    name: "Code coverage report"
+    if: github.event_name == 'pull_request' # Do not run when workflow is triggered by push to main branch
+    runs-on: ubuntu-latest
+    needs: main
+    permissions:
+      contents: read
+      actions: read  # to download code coverage results from "main" job
+      pull-requests: write # write permission needed to comment on PR
+    steps:
+      - uses: fgrosse/go-coverage-report@v1.1.1
+        with:
+          coverage-artifact-name: ${{ env.CODE_COVERAGE_ARTIFACT_NAME }}
+          coverage-file-name: ${{ env.CODE_COVERAGE_FILE_NAME }}

Makefile

@@ -25,7 +25,7 @@ lint: lint-golangci-lint lint-yamllint
 # Test
 test:
 	@echo ">> Running tests for the CLI application"
-	@go test ./... -count=1
+	@go test ./... -count=1 -coverprofile=coverage.out
 
 # Test coverage
 coverage: