tests/SIGCM2.Application.Tests/Common/TimeProviderArgentinaExtensionsTests.cs

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+using FluentAssertions;
+using Microsoft.Extensions.Time.Testing;
+using SIGCM2.Application.Common;
+
+namespace SIGCM2.Application.Tests.Common;
+
+/// <summary>
+/// SUITE-BE-CLOCK — UDT-011 T300.10
+/// Unit tests for TimeProviderArgentinaExtensions.GetArgentinaToday.
+/// Uses FakeTimeProvider for deterministic UTC control.
+/// </summary>
+public sealed class TimeProviderArgentinaExtensionsTests
+{
+    /// <summary>
+    /// 22:30 ART del 30/04 = 01:30 UTC del 01/05.
+    /// UTC lleva al día siguiente, ART debe ser el día anterior.
+    /// </summary>
+    [Fact]
+    public void GetArgentinaToday_A22_30UTCdel01Mayo_Retorna30AbrilArgentina()
+    {
+        // 22:30 ART del 30/04 = 01:30 UTC del 01/05
+        var fake = new FakeTimeProvider();
+        fake.SetUtcNow(new DateTimeOffset(2026, 5, 1, 1, 30, 0, TimeSpan.Zero));
+
+        var result = fake.GetArgentinaToday();
+
+        result.Should().Be(new DateOnly(2026, 4, 30));
+    }
+
+    /// <summary>
+    /// 00:30 ART del 01/05 = 03:30 UTC del 01/05.
+    /// Ambos UTC y ART son el mismo día civil.
+    /// </summary>
+    [Fact]
+    public void GetArgentinaToday_A00_30ARTdel01Mayo_Retorna01MayoArgentina()
+    {
+        // 00:30 ART del 01/05 = 03:30 UTC del 01/05
+        var fake = new FakeTimeProvider();
+        fake.SetUtcNow(new DateTimeOffset(2026, 5, 1, 3, 30, 0, TimeSpan.Zero));
+
+        var result = fake.GetArgentinaToday();
+
+        result.Should().Be(new DateOnly(2026, 5, 1));
+    }
+
+    /// <summary>
+    /// Fin de mes en año bisiesto: 22:30 ART del 28/02/2024 = 01:30 UTC del 29/02/2024.
+    /// UTC cae en día bisiesto 29/02, ART debe devolver 28/02.
+    /// </summary>
+    [Fact]
+    public void GetArgentinaToday_BisiestoEnFinDeMesArgentina_RetornaCorrectoAR()
+    {
+        // 22:30 ART del 28/02/2024 (año bisiesto) = 01:30 UTC del 29/02/2024
+        var fake = new FakeTimeProvider();
+        fake.SetUtcNow(new DateTimeOffset(2024, 2, 29, 1, 30, 0, TimeSpan.Zero));
+
+        var result = fake.GetArgentinaToday();
+
+        result.Should().Be(new DateOnly(2024, 2, 28));
+    }
+
+    /// <summary>
+    /// Cruce de año: 22:30 ART del 31/12/2026 = 01:30 UTC del 01/01/2027.
+    /// UTC es año nuevo, ART debe ser el 31/12 del año anterior.
+    /// </summary>
+    [Fact]
+    public void GetArgentinaToday_FinDeAnio_22_30ARTdel31Dic_Retorna31Dic()
+    {
+        // 22:30 ART del 31/12/2026 = 01:30 UTC del 01/01/2027
+        var fake = new FakeTimeProvider();
+        fake.SetUtcNow(new DateTimeOffset(2027, 1, 1, 1, 30, 0, TimeSpan.Zero));
+
+        var result = fake.GetArgentinaToday();
+
+        result.Should().Be(new DateOnly(2026, 12, 31));
+    }
+}