package main

import "testing"

func TestAdd(t *testing.T) {
	if got := add(2, 3); got != 5 {
		t.Fatalf("add(2, 3) = %d, want 5", got)
	}
}

func TestIncrease(t *testing.T) {
	value := 10
	if got := increase(value); got != 11 {
		t.Fatalf("increase(10) = %d, want 11", got)
	}
	if value != 10 {
		t.Fatalf("caller value = %d, want 10", value)
	}
}

func TestAverage(t *testing.T) {
	tests := []struct {
		name   string
		scores []int
		want   float64
		ok     bool
	}{
		{name: "normal", scores: []int{80, 90, 85}, want: 85, ok: true},
		{name: "fraction", scores: []int{80, 81}, want: 80.5, ok: true},
		{name: "zero", scores: []int{0}, want: 0, ok: true},
		{name: "empty", scores: []int{}, want: 0, ok: false},
		{name: "nil", scores: nil, want: 0, ok: false},
	}
	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			got, ok := average(tt.scores)
			if got != tt.want || ok != tt.ok {
				t.Fatalf("average(%v) = (%v, %t), want (%v, %t)", tt.scores, got, ok, tt.want, tt.ok)
			}
		})
	}
}

func TestSum(t *testing.T) {
	if got := sum(1, 2, 3); got != 6 {
		t.Fatalf("sum(1, 2, 3) = %d, want 6", got)
	}
	if got := sum(); got != 0 {
		t.Fatalf("sum() = %d, want 0", got)
	}
	values := []int{10, 20, 30}
	if got := sum(values...); got != 60 {
		t.Fatalf("sum(%v...) = %d, want 60", values, got)
	}
}