From 48e9d23b1091c9c1399e086dc02a399470a38aca Mon Sep 17 00:00:00 2001
From: Jake Wharton <jw@squareup.com>
Date: Mon, 13 Jul 2020 17:25:09 -0400
Subject: [PATCH] Expose TimeZone through Clock

This creates a single object which can be faked or replaced to control the current time and its geographical location for projecting into local dates and times.
---
 core/commonMain/src/Clock.kt             | 5 ++++-
 core/commonMain/src/TimeZone.kt          | 1 +
 core/commonTest/src/InstantTest.kt       | 6 +++---
 core/commonTest/src/LocalDateTest.kt     | 2 +-
 core/commonTest/src/LocalDateTimeTest.kt | 2 +-
 core/commonTest/src/TimeZoneTest.kt      | 4 ++--
 6 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/core/commonMain/src/Clock.kt b/core/commonMain/src/Clock.kt
index 7a691fb..b56c355 100644
--- a/core/commonMain/src/Clock.kt
+++ b/core/commonMain/src/Clock.kt
@@ -5,6 +5,7 @@
 
 package kotlinx.datetime
 
+import kotlinx.datetime.TimeZone.Companion
 import kotlin.time.Duration
 import kotlin.time.ExperimentalTime
 import kotlin.time.TimeMark
@@ -12,9 +13,11 @@ import kotlin.time.TimeSource
 
 public interface Clock {
     public fun now(): Instant
+    public fun timeZone(): TimeZone
 
     public object System : Clock {
         override fun now(): Instant = @Suppress("DEPRECATION_ERROR") Instant.now()
+        override fun timeZone(): TimeZone = @Suppress("DEPRECATION_ERROR") TimeZone.SYSTEM
     }
 
     public companion object {
@@ -22,7 +25,7 @@ public interface Clock {
     }
 }
 
-public fun Clock.todayAt(timeZone: TimeZone): LocalDate =
+public fun Clock.today(timeZone: TimeZone = timeZone()): LocalDate =
         now().toLocalDateTime(timeZone).date
 
 
diff --git a/core/commonMain/src/TimeZone.kt b/core/commonMain/src/TimeZone.kt
index bdd34c0..648fffc 100644
--- a/core/commonMain/src/TimeZone.kt
+++ b/core/commonMain/src/TimeZone.kt
@@ -9,6 +9,7 @@ public expect open class TimeZone {
     public val id: String
 
     companion object {
+        @Deprecated("Use Clock.System.timeZone() instead", ReplaceWith("Clock.System.timeZone()", "kotlinx.datetime.Clock"), level = DeprecationLevel.ERROR)
         val SYSTEM: TimeZone
         val UTC: TimeZone
         fun of(zoneId: String): TimeZone
diff --git a/core/commonTest/src/InstantTest.kt b/core/commonTest/src/InstantTest.kt
index c26555e..bde9a57 100644
--- a/core/commonTest/src/InstantTest.kt
+++ b/core/commonTest/src/InstantTest.kt
@@ -50,7 +50,7 @@ class InstantTest {
     fun instantToLocalDTConversion() {
         val now = Clock.System.now()
         println(now.toLocalDateTime(TimeZone.UTC))
-        println(now.toLocalDateTime(TimeZone.SYSTEM))
+        println(now.toLocalDateTime(Clock.System.timeZone()))
     }
 
     /* Based on the ThreeTenBp project.
@@ -145,8 +145,8 @@ class InstantTest {
             val instant1 = Instant.fromEpochMilliseconds(millis1)
             val instant2 = Instant.fromEpochMilliseconds(millis2)
 
-            val diff = instant1.periodUntil(instant2, TimeZone.SYSTEM)
-            val instant3 = instant1.plus(diff, TimeZone.SYSTEM)
+            val diff = instant1.periodUntil(instant2, Clock.System.timeZone())
+            val instant3 = instant1.plus(diff, Clock.System.timeZone())
 
             if (instant2 != instant3)
                 println("start: $instant1, end: $instant2, start + diff: $instant3, diff: $diff")
diff --git a/core/commonTest/src/LocalDateTest.kt b/core/commonTest/src/LocalDateTest.kt
index a5bf0df..ad77b1c 100644
--- a/core/commonTest/src/LocalDateTest.kt
+++ b/core/commonTest/src/LocalDateTest.kt
@@ -71,7 +71,7 @@ class LocalDateTest {
 
     @Test
     fun tomorrow() {
-        val today = Clock.System.todayAt(TimeZone.SYSTEM)
+        val today = Clock.System.today()
 
         val nextMonthPlusDay1 = today + 1.calendarMonths + 1.calendarDays
         val nextMonthPlusDay2 = today + (1.calendarMonths + 1.calendarDays)
diff --git a/core/commonTest/src/LocalDateTimeTest.kt b/core/commonTest/src/LocalDateTimeTest.kt
index 966bbd2..ac35600 100644
--- a/core/commonTest/src/LocalDateTimeTest.kt
+++ b/core/commonTest/src/LocalDateTimeTest.kt
@@ -61,7 +61,7 @@ class LocalDateTimeTest {
 
     @Test
     fun getCurrentHMS() {
-        with(Clock.System.now().toLocalDateTime(TimeZone.SYSTEM)) {
+        with(Clock.System.now().toLocalDateTime(Clock.System.timeZone())) {
             println("${hour}h ${minute}m")
         }
     }
diff --git a/core/commonTest/src/TimeZoneTest.kt b/core/commonTest/src/TimeZoneTest.kt
index 403c525..45b00e0 100644
--- a/core/commonTest/src/TimeZoneTest.kt
+++ b/core/commonTest/src/TimeZoneTest.kt
@@ -20,7 +20,7 @@ class TimeZoneTest {
 
     @Test
     fun system() {
-        println(TimeZone.SYSTEM)
+        println(Clock.System.timeZone())
         // TODO: decide how to assert system tz properties
     }
 
@@ -31,7 +31,7 @@ class TimeZoneTest {
         allTzIds.forEach(::println)
 
         assertNotEquals(0, allTzIds.size)
-        assertTrue(TimeZone.SYSTEM.id in allTzIds)
+        assertTrue(Clock.System.timeZone().id in allTzIds)
         assertTrue("UTC" in allTzIds)
     }
 
-- 
2.27.0