epoch should be UTC?

src/libraries/Microsoft.PowerFx.Core/Public/Values/DateTimeValue.cs

@@ -39,37 +39,33 @@ public DateTime GetConvertedValue(TimeZoneInfo timeZoneInfo)
 
         internal static DateTime GetConvertedDateTimeValue(DateTime value, TimeZoneInfo timeZoneInfo)
         {
-            // If timeZoneInfo is null and stored value is in UTC, we don't want to convert.
-            if (timeZoneInfo == null && value.Kind == DateTimeKind.Utc)
-            {
-                timeZoneInfo = TimeZoneInfo.Utc;
-            }
-            else if (timeZoneInfo == null)
+            // Ensure timeZoneInfo is not null; default to local time zone if it is.
+            if (timeZoneInfo == null)
             {
                 timeZoneInfo = TimeZoneInfo.Local;
             }
-
-            // Since we can't convert LocalKind time to UTC, if the time was of kind local just change kind.
-            if (value.Kind == DateTimeKind.Local && timeZoneInfo.Equals(TimeZoneInfo.Utc))
-            {
-                return DateTime.SpecifyKind(value, DateTimeKind.Utc);
-            }
-            else if (value.Kind == DateTimeKind.Local && !timeZoneInfo.Equals(TimeZoneInfo.Utc))
+
+            DateTime result;
+
+            if (value.Kind == DateTimeKind.Local)
             {
-                // This code should be modified as we don't return a UTC time here
-                // https://github.com/microsoft/Power-Fx/issues/1931
-                return DateTime.SpecifyKind(value, DateTimeKind.Unspecified);
+                // Convert from local time to the specified time zone.
+                result = TimeZoneInfo.ConvertTime(value, TimeZoneInfo.Local, timeZoneInfo);
             }
-            else if (value.Kind == DateTimeKind.Unspecified && timeZoneInfo.Equals(TimeZoneInfo.Utc))
+            else if (value.Kind == DateTimeKind.Utc)
             {
-                return TimeZoneInfo.ConvertTimeToUtc(value, timeZoneInfo);
+                // Convert from UTC to the specified time zone.
+                result = TimeZoneInfo.ConvertTimeFromUtc(value, timeZoneInfo);
             }
-            else if (value.Kind == DateTimeKind.Utc && !timeZoneInfo.Equals(TimeZoneInfo.Utc))
+            else 
             {
-                return TimeZoneInfo.ConvertTime(value, timeZoneInfo);
+                // DateTimeKind.Unspecified
+                // Assume the unspecified DateTime is in the specified time zone.
+                // If you need to convert it to another time zone, specify the source time zone.
+                result = DateTime.SpecifyKind(value, DateTimeKind.Unspecified);
             }
 
-            return value;
+            return result;
         }
 
         internal DateTimeValue(IRContext irContext, DateTime value)

src/libraries/Microsoft.PowerFx.Interpreter/Functions/Library.cs

@@ -28,7 +28,12 @@ internal static partial class Library
         /// </summary>
         public static readonly TexlFunction DistinctInterpreterFunction = new DistinctFunction();
 
-        internal static readonly DateTime _epoch = new DateTime(1899, 12, 30, 0, 0, 0, 0);
+        internal static readonly DateTime _epoch = new DateTime(1899, 12, 30, 0, 0, 0, 0, DateTimeKind.Utc);
+
+        internal static DateTime Epoch(TimeZoneInfo tzi)
+        {
+            return TimeZoneInfo.ConvertTimeFromUtc(_epoch, tzi);
+        }
 
         // Helper to get a service or fallback to a default if the service is missing.
         private static T GetService<T>(this IServiceProvider services, T defaultService)

src/libraries/Microsoft.PowerFx.Repl/Repl.cs

@@ -254,6 +254,8 @@ public virtual async Task<ReplResult> HandleCommandAsync(string expression, Canc
                  ServiceProvider = new BasicServiceProvider(this.InnerServices)
             };
 
+            runtimeConfig.SetTimeZone(TimeZoneInfo.Local);
+
             if (this.UserInfo != null)
             {
                 if (!_userEnabled)

src/tests/Microsoft.PowerFx.Interpreter.Tests.Shared/ConfigTests.cs

@@ -35,6 +35,21 @@ public async Task BasicEvaluation()
             Assert.Equal(5.0, result.ToObject());
         }
 
+        [Fact]
+        public async Task TestDecimalToDateTimeCoercion()
+        {
+            // Per expression.
+            var engine = new RecalcEngine();
+            var rc = new RuntimeConfig();
+            rc.SetTimeZone(TimeZoneInfo.Utc);
+
+            var res = await engine.EvalAsync("If(false, DateTime(1899, 12, 30, 0, 0, 0, 0), 0)", CancellationToken.None, runtimeConfig: rc);
+
+            var dt = res.ToObject();
+
+            Assert.Equal(DateTimeKind.Utc, ((DateTime)dt).Kind);
+        }
+
         [Fact]
         public async Task BasicDirectEvalFunc()
         {