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How to check UPPERCASE characters in a string in Golang?

Checking if all characters of a string are Uppercase evaluates to True or False. For example, checking if the string "TEST" is uppercase evaluates to True.

Use strings.ToUpper(s) to check are characters are in uppercase 
package main

import (
	"fmt"
	"strings"
)

func main() {
	s := "UPPERCASE"
	fmt.Println(strings.ToUpper(s) == s) // true

	s = "CAN'T"
	fmt.Println(strings.ToUpper(s) == s) // true
}
Use unicode.IsUpper(s) to verify all characters are in uppercase 
package main

import (
	"fmt"
	"unicode"
)

func IsUpper(s string) bool {
	for _, r := range s {
		if !unicode.IsUpper(r) && unicode.IsLetter(r) {
			return false
		}
	}
	return true
}

func main() {
	fmt.Println(IsUpper("UPPERCASE")) // true
	fmt.Println(IsUpper("CAN'T"))     // true
}
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