add a simple unit test to prevent regression

internal/infra/updater.go

@@ -109,11 +109,11 @@ func putUpdaterInputs(ctx context.Context, cli *client.Client, cert, id string,
 		return fmt.Errorf("failed to copy cert to container: %w", err)
 	}
 
-	data, err := json.Marshal(FileFetcherJobFile{Job: job})
+	data, err := JobFile{Job: job}.ToJSON()
 	if err != nil {
 		return fmt.Errorf("failed to marshal job file: %w", err)
 	}
-	if t, err := tarball(guestInputDir, string(data)); err != nil {
+	if t, err := tarball(guestInputDir, data); err != nil {
 		return fmt.Errorf("failed create input tarball: %w", err)
 	} else if err = cli.CopyToContainer(ctx, id, "/", t, opt); err != nil {
 		return fmt.Errorf("failed to copy input to container: %w", err)
@@ -278,11 +278,16 @@ func (u *Updater) Close() error {
 	})
 }
 
-// FileFetcherJobFile  is the payload passed to file updater containers.
-type FileFetcherJobFile struct {
+// JobFile  is the payload passed to file updater containers.
+type JobFile struct {
 	Job *model.Job `json:"job"`
 }
 
+func (j JobFile) ToJSON() (string, error) {
+	data, err := json.Marshal(j)
+	return string(data), err
+}
+
 func tarball(name, contents string) (*bytes.Buffer, error) {
 	var buf bytes.Buffer
 	t := tar.NewWriter(&buf)

internal/infra/updater_test.go

@@ -1,8 +1,10 @@
 package infra
 
 import (
+	"github.com/dependabot/cli/internal/model"
 	"os"
 	"path/filepath"
+	"strings"
 	"testing"
 )
 
@@ -48,3 +50,22 @@ func Test_mountOptions(t *testing.T) {
 		}
 	}
 }
+
+func TestJobFile_ToJSON(t *testing.T) {
+	t.Run("empty commit doesn't pass in empty string", func(t *testing.T) {
+		job := JobFile{
+			Job: &model.Job{
+				Source: model.Source{
+					Commit: "",
+				},
+			},
+		}
+		json, err := job.ToJSON()
+		if err != nil {
+			t.Fatal(err)
+		}
+		if strings.Contains(json, `"commit"`) {
+			t.Errorf("expected JSON to not contain commit: %v", json)
+		}
+	})
+}