random_test.go

package strutil

import (
	"fmt"
	"testing"
)

var randCounter = 0

type dummyRandReader struct {
}

func (r *dummyRandReader) Read(p []byte) (n int, err error) {
	for i := range p {
		p[i] = byte(randCounter)
		randCounter++
	}
	return len(p), err
}

func TestRandom(t *testing.T) {
	oldReader := randReader
	randReader = &dummyRandReader{}
	tests := []struct {
		input    string
		length   int
		expected string
	}{
		{"abcdefghij", 5, "abcde"},
		{"abcdefghij", 1, "a"},
		{"abc", 6, "abcabc"},
		{"", 5, ""},
		{"aaa", 5, "aaaaa"},
	}

	for i, test := range tests {
		randCounter = 0
		output, _ := Random(test.input, test.length)
		Assert(t, test.expected, output, "Test case %d is not successful\n", i)
	}
	randReader = oldReader
}

func ExampleRandom() {
	fmt.Println(Random("abcdefghik", 5))
}