package main

import (
	"strings"
	"testing"

	"github.com/google/go-cmp/cmp"
)

func TestBuildNGrams(t *testing.T) {
	const testWordList = `abc
abd
def
`

	got, err := buildNGrams(strings.NewReader(testWordList))
	if err != nil {
		t.Fatalf("buildNGrams failed: %s", err)
	}
	want := map[biGram][]choice{
		{-1, -1}:   {{'a', 2}, {'d', 3}},
		{-1, 'a'}:  {{'b', 2}},
		{-1, 'd'}:  {{'e', 1}},
		{'a', 'b'}: {{'c', 1}, {'d', 2}},
		{'b', 'c'}: {{-1, 1}},
		{'b', 'd'}: {{-1, 1}},
		{'d', 'e'}: {{'f', 1}},
		{'e', 'f'}: {{-1, 1}},
	}
	if diff := cmp.Diff(want, got, cmp.AllowUnexported(biGram{}, choice{})); diff != "" {
		t.Errorf("buildNGrams(%q) returned unexpected diff (-want +got):\n%s", testWordList, diff)
	}
}