Setup GitHub Actions for auto remove trailing whitespaces (#4269)

* Setup GitHub Actions for auto remove trailing whitespaces

This PR setup GitHub Actions for auto remove trailing whitespaces,
if any non-go files are touched (.git directory are ignored)
Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

* Remove TestTrailingWhitespace in presubmit tests
Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

* paths and paths-ignore are mutually exlcusive so only keep paths-ignore
Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

* Remove redundent bufio import
Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

.github/workflows/whitespace.yml

+name: Remove Trailing Whitespaces
+
+on:
+  push:
+    branches:
+      - 'master'
+    paths-ignore:
+      - '**.go'
+
+jobs:
+  fix:
+    runs-on: ubuntu-latest
+    steps:
+      -
+        name: Checkout
+        uses: actions/checkout@v2
+      -
+        name: Remove Trailing Whitespaces
+        run: |
+          find . -not -path '*/\.git/*' -type f -not -name '*.go' -exec sed -i '' 's/[[:space:]]\{1,\}$//' {} \+
+      -
+        name: Set up Git
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: |
+          git config user.name "coredns-auto-trailing-whitespaces[bot]"
+          git config user.email "coredns-auto-trailing-whitespaces[bot]@users.noreply.github.com"
+          git remote set-url origin https://x-access-token:${GITHUB_TOKEN}@github.com/${GITHUB_REPOSITORY}.git
+      -
+        name: Commit and push changes
+        run: |
+          git add .
+          if output=$(git status --porcelain) && [ ! -z "$output" ]; then
+            git commit -m 'auto remove trailing whitespaces'
+            git push
+          fi

test/presubmit_test.go

@@ -3,7 +3,6 @@ package test
 // These tests check for meta level items, like trailing whitespace, correct file naming etc.
 
 import (
-	"bufio"
 	"fmt"
 	"go/ast"
 	"go/parser"
@@ -16,67 +15,6 @@ import (
 	"unicode"
 )
 
-func TestTrailingWhitespace(t *testing.T) {
-	walker := hasTrailingWhitespaceWalker{}
-	err := filepath.Walk("..", walker.walk)
-
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	if len(walker.Errors) > 0 {
-		for _, err = range walker.Errors {
-			t.Error(err)
-		}
-	}
-}
-
-type hasTrailingWhitespaceWalker struct {
-	Errors []error
-}
-
-func (w *hasTrailingWhitespaceWalker) walk(path string, info os.FileInfo, _ error) error {
-	// Only handle regular files, skip files that are executable and skip file in the
-	// root that start with a .
-	if !info.Mode().IsRegular() {
-		return nil
-	}
-	if info.Mode().Perm()&0111 != 0 {
-		return nil
-	}
-	if strings.HasPrefix(path, "../.") {
-		return nil
-	}
-	if strings.Contains(path, "/vendor") {
-		return nil
-	}
-
-	file, err := os.Open(path)
-	if err != nil {
-		return nil
-	}
-	defer file.Close()
-
-	scanner := bufio.NewScanner(file)
-	for i := 1; scanner.Scan(); i++ {
-		text := scanner.Text()
-		trimmed := strings.TrimRightFunc(text, unicode.IsSpace)
-		if len(text) != len(trimmed) {
-			absPath, _ := filepath.Abs(path)
-			w.Errors = append(w.Errors, fmt.Errorf("file %q has trailing whitespace at line %d, text: %q", absPath, i, text))
-		}
-	}
-
-	err = scanner.Err()
-
-	if err != nil {
-		absPath, _ := filepath.Abs(path)
-		err = fmt.Errorf("file %q: %v", absPath, err)
-	}
-
-	return err
-}
-
 func TestFileNameHyphen(t *testing.T) {
 	walker := hasHyphenWalker{}
 	err := filepath.Walk("..", walker.walk)