ErsatzTV.Core.Tests/Scheduling/PlayoutModeSchedulerBaseTests.cs

@@ -1,4 +1,4 @@
-using ErsatzTV.Core.Domain;
+using ErsatzTV.Core.Domain;
 using ErsatzTV.Core.Domain.Filler;
 using ErsatzTV.Core.Interfaces.Scheduling;
 using ErsatzTV.Core.Scheduling;
@@ -57,7 +57,13 @@ public class PlayoutModeSchedulerBaseTests : SchedulerTestBase
                     startState,
                     CollectionEnumerators(scheduleItem, enumerator),
                     scheduleItem,
-                    new PlayoutItem(),
+                    // real start time, not default MinValue: the mid-roll Pad math subtracts minutes,
+                    // which underflows DateTimeOffset.MinValue under a non-UTC local offset (#24)
+                    new PlayoutItem
+                    {
+                        Start = startState.CurrentTime.UtcDateTime,
+                        Finish = startState.CurrentTime.UtcDateTime
+                    },
                     new List<MediaChapter>(),
                     new PlayoutBuildWarnings(),
                     _cancellationToken);
@@ -110,7 +116,13 @@ public class PlayoutModeSchedulerBaseTests : SchedulerTestBase
                     startState,
                     enumerators,
                     scheduleItem,
-                    new PlayoutItem(),
+                    // real start time, not default MinValue: the mid-roll Pad math subtracts minutes,
+                    // which underflows DateTimeOffset.MinValue under a non-UTC local offset (#24)
+                    new PlayoutItem
+                    {
+                        Start = startState.CurrentTime.UtcDateTime,
+                        Finish = startState.CurrentTime.UtcDateTime
+                    },
                     new List<MediaChapter> { new() },
                     new PlayoutBuildWarnings(),
                     _cancellationToken);

docs/contributing.md

@@ -118,8 +118,11 @@ exceptions for control flow.
   string — `ErsatzTV.FFmpeg.Tests/PipelineBuilderBaseTests.cs`); **golden-file tests** for
   Jellyfin-facing output (`ErsatzTV.Core.Tests/Iptv/ChannelPlaylistGoldenTests.cs`, regen via
   `ETV_UPDATE_GOLDENS=1`, ersatztv#11); **architecture tests** (§1, ersatztv#12).
-- Run local tests with **`TZ=UTC`** to match CI (a couple of `DateTimeOffset` scheduling tests are
-  timezone-sensitive — ersatztv#24). CI uses `dotnet test … --blame-hang-timeout 2m`.
+- The suite is **timezone-independent** — the previously timezone-sensitive `DateTimeOffset`
+  filler-scheduling tests were fixed (ersatztv#24) by giving fixtures realistic times instead of the
+  default `DateTime.MinValue`, which underflowed `DateTimeOffset.MinValue` under a non-UTC offset.
+  When constructing test `PlayoutItem`s, set a real `Start` (e.g. `startState.CurrentTime.UtcDateTime`),
+  not the default. CI runs UTC and uses `dotnet test … --blame-hang-timeout 2m`.
 
 ## 9. Build / CI