migrate CI to GitHub Actions

use codecov.io to report on code coverage.
fix a few issues raised by golangci-lint

.github/workflows/linter.yaml

@@ -0,0 +1,18 @@
+on: [push, pull_request]
+name: linter
+
+jobs:
+  lint:
+    strategy:
+      matrix:
+        go-version: [1.x]
+        platform: [ubuntu-latest]
+    runs-on: ${{ matrix.platform }}
+
+    steps:
+    - uses: actions/checkout@v2
+
+    - name: golangci-lint
+      uses: golangci/golangci-lint-action@v2
+      with:
+        version: v1.41

.github/workflows/tests.yaml

@@ -0,0 +1,46 @@
+on: [push, pull_request]
+name: tests
+
+jobs:
+  test:
+    strategy:
+      matrix:
+        go-version: [1.x, 1.15.x]
+        platform: [ubuntu-latest]
+        include:
+          # only update test coverage stats with the most recent go version on linux
+          - go-version: 1.x
+            platform: ubuntu-latest
+            update-coverage: true
+    runs-on: ${{ matrix.platform }}
+
+    permissions:
+      # styfle/cancel-workflow-action needs to be able to cancel existing action workflows
+      actions: write
+
+    steps:
+    - name: Cancel previous
+      uses: styfle/cancel-workflow-action@89f242ee29e10c53a841bfe71cc0ce7b2f065abc #0.9.0
+      with:
+        access_token: ${{ github.token }}
+
+    - uses: actions/setup-go@v2
+      with:
+        go-version: ${{ matrix.go-version }}
+    - uses: actions/checkout@v2
+
+    - name: Cache go modules
+      uses: actions/cache@v2
+      with:
+        path: |
+          ~/.cache/go-build
+          ~/go/pkg/mod
+        key: ${{ runner.os }}-go-${{ hashFiles('**/go.sum') }}
+        restore-keys: ${{ runner.os }}-go-
+
+    - name: Run go test
+      run: go test -v -race -coverprofile coverage.txt -covermode atomic ./...
+
+    - name: Upload coverage to Codecov
+      if: ${{ matrix.update-coverage }}
+      uses: codecov/codecov-action@v2

.golangci.yaml

@@ -0,0 +1,12 @@
+linters:
+  enable:
+    - dogsled
+    - dupl
+    - gofmt
+    - goimports
+    - misspell
+    - nakedret
+    - stylecheck
+    - unconvert
+    - unparam
+    - whitespace

main.go

@@ -178,7 +178,9 @@ func main() {
 	}()
 
 	for _, d := range flag.Args() {
-		walk(ch, d)
+		if err := walk(ch, d); err != nil {
+			log.Fatal(err)
+		}
 	}
 	close(ch)
 	<-done
@@ -189,8 +191,8 @@ type file struct {
 	mode os.FileMode
 }
 
-func walk(ch chan<- *file, start string) {
-	filepath.Walk(start, func(path string, fi os.FileInfo, err error) error {
+func walk(ch chan<- *file, start string) error {
+	return filepath.Walk(start, func(path string, fi os.FileInfo, err error) error {
 		if err != nil {
 			log.Printf("%s error: %v", path, err)
 			return nil

tmpl.go

@@ -68,7 +68,7 @@ func fetchTemplate(license string, templateFile string, spdx spdxFlag) (string,
 				// unknown license, but SPDX headers requested
 				t = tmplSPDX
 			} else {
-				return "", fmt.Errorf("unknown license: %q. Include the '-s' flag to request SPDX style headers using this license.", license)
+				return "", fmt.Errorf("unknown license: %q. Include the '-s' flag to request SPDX style headers using this license", license)
 			}
 		} else if spdx == spdxOn {
 			// append spdx headers to recognized license

tmpl_test.go

@@ -40,7 +40,7 @@ func TestFetchTemplate(t *testing.T) {
 	}{
 		// custom template files
 		{
-			"non-existant template file",
+			"non-existent template file",
 			"",
 			"/does/not/exist",
 			spdxOff,
@@ -62,7 +62,7 @@ func TestFetchTemplate(t *testing.T) {
 			"",
 			spdxOff,
 			"",
-			errors.New(`unknown license: "unknown". Include the '-s' flag to request SPDX style headers using this license.`),
+			errors.New(`unknown license: "unknown". Include the '-s' flag to request SPDX style headers using this license`),
 		},
 
 		// pre-defined license templates, no SPDX