Test: Add Go linting (gofmt) to CI

.github/workflows/tests.yml

@@ -8,7 +8,7 @@ jobs:
   test:
     strategy:
       matrix:
-        go-version: ['1.23']
+        go-version: [stable]
         os: [ubuntu-latest, windows-latest, macos-latest]
     runs-on: ${{ matrix.os }}
     steps:
@@ -17,7 +17,7 @@ jobs:
         go-version: ${{ matrix.go-version }}
         cache: false
     - uses: actions/checkout@v4
-    - name: Run Go tests
+    - name: Set up Go environment
       uses: actions/cache@v4
       with:
         path: |
@@ -26,11 +26,17 @@ jobs:
         key: ${{ runner.os }}-go-${{ hashFiles('**/go.sum') }}
         restore-keys: |
           ${{ runner.os }}-go-
-    - run: go test -p 1 ./internal/storage ./server ./internal/smtpd ./internal/pop3 ./internal/tools ./internal/html2text ./internal/htmlcheck ./internal/linkcheck -v
-    - run: go test -p 1 ./internal/storage ./internal/html2text -bench=.
+    - name: Test Go linting (gofmt)
+      if: startsWith(matrix.os, 'ubuntu') == true
+      # https://olegk.dev/github-actions-and-go
+      run: gofmt -s -w . && git diff --exit-code
+    - name: Run Go tests
+      run: go test -p 1 ./internal/storage ./server ./internal/smtpd ./internal/pop3 ./internal/tools ./internal/html2text ./internal/htmlcheck ./internal/linkcheck -v
+    - name: Run Go benchmarking
+      run: go test -p 1 ./internal/storage ./internal/html2text -bench=.
     
     # build the assets
-    - name: Build web UI
+    - name: Set up node environment
       if: startsWith(matrix.os, 'ubuntu') == true
       uses: actions/setup-node@v4
       with: