Validate template syntax when building binary fixes gobuffalo#840

buffalo/cmd/build/builder.go

@@ -29,6 +29,7 @@ func New(ctx context.Context, opts Options) *Builder {
 
 	b.steps = []func() error{
 		b.prepTarget,
+		b.validateTemplates,
 		b.transformMain,
 		b.createBuildMain,
 		b.prepAPackage,

buffalo/cmd/build/templates.go

@@ -1,7 +1,50 @@
 package build
 
 import (
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"strings"
+
 	"github.com/gobuffalo/packr"
+	"github.com/gobuffalo/plush"
+	"github.com/pkg/errors"
 )
 
 var templates = packr.NewBox("./templates")
+
+func (b *Builder) validateTemplates() error {
+	errs := []string{}
+	err := filepath.Walk(filepath.Join(b.App.Root, "templates"), func(path string, info os.FileInfo, err error) error {
+		if info == nil || info.IsDir() {
+			return nil
+		}
+
+		ext := filepath.Ext(path)
+		if ext != ".html" && ext != ".md" {
+			return nil
+		}
+
+		b, err := ioutil.ReadFile(path)
+		if err != nil {
+			return errors.WithStack(err)
+		}
+
+		if _, err = plush.Parse(string(b)); err != nil {
+			errs = append(errs, fmt.Sprintf("template error in file %s: %s", path, err.Error()))
+		}
+
+		return nil
+	})
+
+	if err != nil {
+		return errors.WithStack(err)
+	}
+
+	if len(errs) > 0 {
+		return errors.New(strings.Join(errs, "\n"))
+	}
+
+	return nil
+}