contains.go

package contains

import (
	"regexp"

	"strings"
)

func ContainsToUpper(s, substr string) bool {
	return strings.Contains(strings.ToUpper(s), strings.ToUpper(substr))
}

func ContainsRegex(s, substr string) (match bool) {
	match, _ = regexp.MatchString("(?i)"+substr, s)
	return match
}

contains_test.go

package contains

import "testing"

// Run benchmarks with: go test -bench .

var tests = []struct {
	str, substr string
	result      bool
}{
	{"foobar", "foo", true},
	{"foObar", "foo", true},
	{"foobar", "foO", true},
	{"foobar", "foO1", false},
}

func TestContainsToUpper(t *testing.T) {
	for _, test := range tests {
		if ContainsToUpper(test.str, test.substr) != test.result {
			t.Fatal(test)
		}
	}
}

func TestContainsRegex(t *testing.T) {
	for _, test := range tests {
		if ContainsRegex(test.str, test.substr) != test.result {
			t.Fatal(test)
		}
	}
}

func BenchmarkContainsToUpper(b *testing.B) {
	for idx := 0; idx < b.N; idx++ {
		for _, test := range tests {
			ContainsToUpper(test.str, test.substr)
		}
	}
}

func BenchmarkContainsRegex(b *testing.B) {
	for idx := 0; idx < b.N; idx++ {
		for _, test := range tests {
			ContainsRegex(test.str, test.substr)
		}
	}
}