Validate templates by doing a test run

pkg/cmd/root.go

@@ -7,8 +7,8 @@ var Root = &cli.Command{
 }
 
 func Run() {
+	// TODO trap c-c to rollback transactions
 	// TODO use command factories instead of global command variables
-
 	Init.PersistentFlags().BoolP("force", "f", false, "Recreate directories if they exist")
 	Root.AddCommand(Init)
 

pkg/cmd/use.go

@@ -22,6 +22,8 @@ func TemplateInRegistry(name string) (bool, error) {
 	return ok, nil
 }
 
+// TODO add --use-defaults flag to execute a template without user prompts
+// TODO add --use-cache flag to execute a template from previous answers to prompts
 var Use = &cli.Command{
 	Use:   "use <template-name> <target-dir>",
 	Short: "Executes a project template",
@@ -50,12 +52,12 @@ var Use = &cli.Command{
 		}
 
 		if err := tmpl.Execute(targetDir); err != nil {
-			// Delete if execute transaction fails
+			// Deletes the target dir if execute transaction fails
 			defer os.RemoveAll(targetDir)
 
 			exit.Fatal(fmt.Errorf("use: %s", err))
 		}
 
-		exit.OK("Successfully executed the project template %v on %v", tmplName, targetDir)
+		exit.OK("Successfully executed the project template %v in %v", tmplName, targetDir)
 	},
 }

pkg/cmd/util/validation.go

@@ -3,8 +3,11 @@ package util
 import (
 	"errors"
 	"fmt"
+	"io/ioutil"
+	"os"
 	"path/filepath"
 
+	"github.com/tmrts/tmplt/pkg/template"
 	"github.com/tmrts/tmplt/pkg/util/osutil"
 	"github.com/tmrts/tmplt/pkg/util/validate"
 )
@@ -45,6 +48,23 @@ func ValidateArgs(args []string, validations []validate.Argument) error {
 	return nil
 }
 
+func testTemplate(path string) error {
+	tmpDir, err := ioutil.TempDir("", "tmplt-validation-test")
+	if err != nil {
+		return err
+	} else {
+		defer os.RemoveAll(tmpDir)
+	}
+
+	tmpl, err := template.Get(path)
+	if err != nil {
+		return err
+	}
+
+	// TODO add --use-defaults flag to stop asking for user input
+	return tmpl.Execute(tmpDir)
+}
+
 func ValidateTemplate(tmplPath string) (bool, error) {
 	if exists, err := osutil.DirExists(tmplPath); !exists {
 		if err != nil {
@@ -62,5 +82,9 @@ func ValidateTemplate(tmplPath string) (bool, error) {
 		return false, fmt.Errorf("template should contain %q directory", "template")
 	}
 
+	if err := testTemplate(tmplPath); err != nil {
+		return false, err
+	}
+
 	return true, nil
 }

pkg/cmd/validate.go

@@ -24,6 +24,6 @@ var Validate = &cli.Command{
 
 		MustValidateTemplate(templatePath)
 
-		exit.OK("Template is valid.")
+		exit.OK("Template is valid")
 	},
 }