hrynco-common/HrynCo.Common.Tests/ClockTests.cs

namespace HrynCo.Common.Tests;

using HrynCo.Common;
using FluentAssertions;
using Xunit;

public sealed class ClockTests
{
    [Fact]
    public void Clock_ShouldExposeUtcAndLocalTimeCloseToConstructionTime()
    {
        DateTimeOffset initialUtcNow = new(2026, 04, 30, 12, 0, 0, TimeSpan.Zero);

        var clock = new Clock(initialUtcNow);

        clock.UtcNow.Should().BeCloseTo(initialUtcNow, TimeSpan.FromSeconds(1));
        clock.Now.Should().BeCloseTo(initialUtcNow.ToLocalTime(), TimeSpan.FromSeconds(1));
    }

    [Fact]
    public void GetNextDayOfWeek_ShouldReturnNextMatchingDay()
    {
        var clock = new Clock(new DateTimeOffset(2026, 04, 30, 12, 0, 0, TimeSpan.Zero));

        clock.GetNextDayOfWeek(DayOfWeek.Friday).Should().Be(new DateOnly(2026, 5, 1));
        clock.GetNextDayOfWeek(DayOfWeek.Thursday).Should().Be(new DateOnly(2026, 5, 7));
    }

    [Fact]
    public void GetLastDayOfMonth_ShouldReturnMonthEnd()
    {
        var clock = new Clock(new DateTimeOffset(2026, 02, 10, 8, 0, 0, TimeSpan.Zero));

        clock.GetLastDayOfMonth().Should().Be(new DateOnly(2026, 2, 28));
    }

    [Fact]
    public void GetNextMonthStart_ShouldReturnFirstDayOfNextMonth()
    {
        var clock = new Clock(new DateTimeOffset(2026, 12, 15, 8, 0, 0, TimeSpan.Zero));

        clock.GetNextMonthStart().Should().Be(new DateOnly(2027, 1, 1));
    }
}