Report structurally invalid workflows to users (#37116) (#37164)

Backport #37116 by @bircni

`model.ReadWorkflow` succeeds for YAML that is syntactically valid but
fails deeper parsing in `jobparser.Parse` (e.g. blank lines inside `run:
|` blocks cause a SetJob round-trip error). Add
`ValidateWorkflowContent` which runs the full `jobparser.Parse` to catch
these cases, and use it in the file view, the actions workflow list, and
the workflow detection loop so users see the error instead of silently
getting a 500 or a dropped workflow.

Fixes #37115

Signed-off-by: Nicolas <bircni@icloud.com>
Co-authored-by: Nicolas <bircni@icloud.com>
Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>
Co-authored-by: Zettat123 <zettat123@gmail.com>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

modules/actions/workflows.go

@@ -103,10 +103,20 @@ func GetEventsFromContent(content []byte) ([]*jobparser.Event, error) {
 	if err != nil {
 		return nil, err
 	}
+	if err := ValidateWorkflowContent(content); err != nil {
+		return nil, err
+	}
 
 	return events, nil
 }
 
+// ValidateWorkflowContent catches structural errors (e.g. blank lines in run: | blocks)
+// that model.ReadWorkflow alone does not detect.
+func ValidateWorkflowContent(content []byte) error {
+	_, err := jobparser.Parse(content)
+	return err
+}
+
 func DetectWorkflows(
 	gitRepo *git.Repository,
 	commit *git.Commit,

modules/actions/workflows_test.go

@@ -9,16 +9,26 @@ import (
 	"code.gitea.io/gitea/modules/git"
 	"code.gitea.io/gitea/modules/setting"
 	api "code.gitea.io/gitea/modules/structs"
+	"code.gitea.io/gitea/modules/test"
 	webhook_module "code.gitea.io/gitea/modules/webhook"
 
 	"github.com/stretchr/testify/assert"
 )
 
+func fullWorkflowContent(part string) []byte {
+	return []byte(`
+name: test
+` + part + `
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - run: echo hello
+`)
+}
+
 func TestIsWorkflow(t *testing.T) {
-	oldDirs := setting.Actions.WorkflowDirs
-	defer func() {
-		setting.Actions.WorkflowDirs = oldDirs
-	}()
+	defer test.MockVariableValue(&setting.Actions.WorkflowDirs)()
 
 	tests := []struct {
 		name     string
@@ -218,7 +228,7 @@ func TestDetectMatched(t *testing.T) {
 
 	for _, tc := range testCases {
 		t.Run(tc.desc, func(t *testing.T) {
-			evts, err := GetEventsFromContent([]byte(tc.yamlOn))
+			evts, err := GetEventsFromContent(fullWorkflowContent(tc.yamlOn))
 			assert.NoError(t, err)
 			assert.Len(t, evts, 1)
 			assert.Equal(t, tc.expected, detectMatched(nil, tc.commit, tc.triggedEvent, tc.payload, evts[0]))
@@ -373,7 +383,7 @@ func TestMatchIssuesEvent(t *testing.T) {
 
 	for _, tc := range testCases {
 		t.Run(tc.desc, func(t *testing.T) {
-			evts, err := GetEventsFromContent([]byte(tc.yamlOn))
+			evts, err := GetEventsFromContent(fullWorkflowContent(tc.yamlOn))
 			assert.NoError(t, err)
 			assert.Len(t, evts, 1)