Add template test

+package beego
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestBuildTemplate(t *testing.T) {
+	dir := "_beeTmp"
+	files := []string{
+		"1.tpl",
+		"2.html",
+		"3.htmltpl",
+		"4.mystyle",
+	}
+	if err := os.MkdirAll(dir, 0777); err != nil {
+		t.Fatal(err)
+	}
+	for _, name := range files {
+		if _, err := os.Create(filepath.Join(dir, name)); err != nil {
+			t.Fatal(err)
+		}
+	}
+	if err := BuildTemplate(dir); err != nil {
+		t.Fatal(err)
+	}
+	if len(BeeTemplates) != 1 {
+		t.Fatalf("should be 1 but got %v", len(BeeTemplates))
+	}
+	for _, v := range BeeTemplates {
+		if len(v.Templates()) != 3 {
+			t.Errorf("should be 3 but got %v", len(v.Templates()))
+		}
+	}
+
+	AddTemplateExt("mystyle")
+	if err := BuildTemplate(dir); err != nil {
+		t.Fatal(err)
+	}
+	if len(BeeTemplates) != 1 {
+		t.Fatalf("should be 1 but got %v", len(BeeTemplates))
+	}
+	for _, v := range BeeTemplates {
+		if len(v.Templates()) != 4 {
+			t.Errorf("should be 4 but got %v", len(v.Templates()))
+		}
+	}
+}