Try to find the edge cases that work across platforms

Author: dkhalanskyjb

core/common/test/samples/InstantSamples.kt

@@ -234,11 +234,11 @@ class InstantSamples {
 
     @Test
     fun minusDateTimeUnit() {
-        val startInstant = Instant.parse("2024-05-02T08:55:40.322Z")
+        val startInstant = Instant.parse("2024-03-28T02:04:56.256Z")
         val twoYearsEarlierInBerlin = startInstant.minus(2, DateTimeUnit.YEAR, TimeZone.of("Europe/Berlin"))
-        check(twoYearsEarlierInBerlin == Instant.parse("2022-05-02T08:55:40.322Z"))
+        check(twoYearsEarlierInBerlin == Instant.parse("2022-03-28T01:04:56.256Z"))
         val twoYearsEarlierInCairo = startInstant.minus(2, DateTimeUnit.YEAR, TimeZone.of("Africa/Cairo"))
-        check(twoYearsEarlierInCairo == Instant.parse("2022-05-02T09:55:40.322Z"))
+        check(twoYearsEarlierInCairo == Instant.parse("2022-03-28T02:04:56.256Z"))
     }
 
     @Test

core/common/test/samples/TimeZoneSamples.kt

@@ -7,6 +7,7 @@ package kotlinx.datetime.test.samples
 
 import kotlinx.datetime.*
 import kotlinx.datetime.format.*
+import kotlin.random.*
 import kotlin.test.*
 
 class TimeZoneSamples {
@@ -174,16 +175,15 @@ class TimeZoneSamples {
         check(instant == Instant.parse("2023-06-02T11:00:00Z"))
     }
 
-    @Ignore // fails on Windows; TODO investigate
     @Test
     fun atStartOfDayIn() {
-        val zone = TimeZone.of("America/Cuiaba")
+        val zone = TimeZone.of("Africa/Cairo")
         // The normal case where `atStartOfDayIn` returns the instant of 00:00:00 in the given time zone.
         val normalDate = LocalDate(2023, 6, 2)
         val startOfDay = normalDate.atStartOfDayIn(zone)
         check(startOfDay.toLocalDateTime(zone) == normalDate.atTime(hour = 0, minute = 0))
         // The edge case where 00:00:00 does not exist in this time zone on this date due to clocks moving forward.
-        val dateWithoutMidnight = LocalDate(1985, 11, 2)
+        val dateWithoutMidnight = LocalDate(2023, 4, 28)
         val startOfDayWithoutMidnight = dateWithoutMidnight.atStartOfDayIn(zone)
         check(startOfDayWithoutMidnight.toLocalDateTime(zone) == dateWithoutMidnight.atTime(hour = 1, minute = 0))
     }