Write some tests for the style wrapper

tools/utils/style/api.go

@@ -0,0 +1,30 @@
+// License: GPLv3 Copyright: 2022, Kovid Goyal, <kovid at kovidgoyal.net>
+
+package style
+
+import (
+	"fmt"
+	"strings"
+)
+
+type Context struct {
+	AllowEscapeCodes bool
+}
+
+func (self *Context) SprintFunc(spec string) func(args ...interface{}) string {
+	p := prefix_for_spec(spec)
+	s := suffix_for_spec(spec)
+
+	return func(args ...interface{}) string {
+		body := fmt.Sprint(args...)
+		if !self.AllowEscapeCodes {
+			return body
+		}
+		b := strings.Builder{}
+		b.Grow(len(p) + len(body) + len(s))
+		b.WriteString(p)
+		b.WriteString(body)
+		b.WriteString(s)
+		return b.String()
+	}
+}