package combinations

import (
	"testing"

	"github.com/stretchr/testify/require"
)

func TestCombinations(t *testing.T) {
	{
		base := []string{"1", "2"}
		require.ElementsMatch(t, [][]string{{"1"}, {"2"}}, Combinations(base, 1))
		require.ElementsMatch(t, [][]string{{"1", "2"}}, Combinations(base, 2))
	}

	{
		base := []int{1, 2, 3}
		require.ElementsMatch(t, [][]int{{1}, {2}, {3}}, Combinations(base, 1))
		require.ElementsMatch(t, [][]int{{1, 2}, {1, 3}, {2, 3}}, Combinations(base, 2))
		require.ElementsMatch(t, [][]int{{1, 2, 3}}, Combinations(base, 3))
	}

	{
		base := []int{1, 2, 3, 4}
		require.ElementsMatch(t, [][]int{{1}, {2}, {3}, {4}}, Combinations(base, 1))
		require.ElementsMatch(t, [][]int{{1, 2}, {1, 3}, {1, 4}, {2, 3}, {2, 4}, {3, 4}}, Combinations(base, 2))
		require.ElementsMatch(t, [][]int{{1, 2, 3}, {1, 3, 4}, {2, 3, 4}, {1, 2, 4}}, Combinations(base, 3))
		require.ElementsMatch(t, [][]int{{1, 2, 3, 4}}, Combinations(base, 4))
	}

	for n := 0; n < 21; n++ {
		arr := make([]int, n)
		for i, v := range arr {
			arr[i] = v
		}

		for r := n; r > 0; r-- {
			require.Len(t, Combinations(arr, r), resultSize(n, r), "comb(%d)")
		}
	}
}