fix timestamp format

android/src/test/java/com/segment/analytics/kotlin/android/EventsFileTests.kt

@@ -6,9 +6,9 @@ import com.segment.analytics.kotlin.core.TrackEvent
 import com.segment.analytics.kotlin.core.emptyJsonObject
 import com.segment.analytics.kotlin.core.utilities.EncodeDefaultsJson
 import com.segment.analytics.kotlin.core.utilities.EventsFileManager
-import com.segment.analytics.kotlin.core.utilities.dateTimeNowString
+import com.segment.analytics.kotlin.core.utilities.SegmentInstant
 import io.mockk.every
-import io.mockk.mockkStatic
+import io.mockk.mockkObject
 import kotlinx.coroutines.test.runTest
 import kotlinx.serialization.encodeToString
 import kotlinx.serialization.json.buildJsonObject
@@ -32,10 +32,8 @@ class EventsFileTests {
     private val directory = File("/tmp/analytics-android-test/")
 
     init {
-        mockkStatic(Instant::class)
-        mockkStatic(::dateTimeNowString)
-        every { dateTimeNowString() } returns Date(0).toInstant().toString()
-        every { Instant.now() } returns Date(0).toInstant()
+        mockkObject(SegmentInstant)
+        every { SegmentInstant.now() } returns Date(0).toInstant().toString()
     }
 
     @BeforeEach

core/src/main/java/com/segment/analytics/kotlin/core/Events.kt

@@ -1,6 +1,6 @@
 package com.segment.analytics.kotlin.core
 
-import com.segment.analytics.kotlin.core.utilities.dateTimeNowString
+import com.segment.analytics.kotlin.core.utilities.SegmentInstant
 import kotlinx.serialization.DeserializationStrategy
 import kotlinx.serialization.SerialName
 import kotlinx.serialization.Serializable
@@ -80,7 +80,7 @@ sealed class BaseEvent {
     }
 
     internal fun applyBaseData() {
-        this.timestamp = dateTimeNowString()
+        this.timestamp = SegmentInstant.now()
         this.context = emptyJsonObject
         this.messageId = UUID.randomUUID().toString()
     }

core/src/main/java/com/segment/analytics/kotlin/core/utilities/DateTimeUtils.kt

@@ -3,19 +3,34 @@ package com.segment.analytics.kotlin.core.utilities
 import java.text.SimpleDateFormat
 import java.util.*
 
-/**
- * This function is a replacement for Instant.now().toString(). It produces strings in a
- * compatible format.
- *
- * Ex:
- * Instant.now():       2023-04-19T04:03:46.880969Z
- * dateTimeNowString(): 2023-04-19T04:03:46.880Z
- */
-fun dateTimeNowString(): String {
+object SegmentInstant {
+
     // Note, we should specify locale = Locale.ROOT, otherwise the timestamp returned will use
     // the default locale, which may not be what we want.
-    val sdf = SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss'.'Szzz", Locale.ROOT)
-    val utc = TimeZone.getTimeZone("UTC");
-    sdf.timeZone = utc;
-    return sdf.format(Date()).replace("UTC", "Z")
+    private val formatter: SimpleDateFormat =
+        SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss'.'SSSzzz", Locale.ROOT).apply {
+            timeZone = TimeZone.getTimeZone("UTC")
+        }
+
+    /**
+     * This function is a replacement for Instant.now().toString(). It produces strings in a
+     * compatible format.
+     *
+     * Ex:
+     * Instant.now():       2023-04-19T04:03:46.880969Z
+     * dateTimeNowString(): 2023-04-19T04:03:46.880Z
+     */
+    fun now(): String {
+        return from(Date())
+    }
+
+    internal fun from(date: Date): String {
+        // internal use only. for testing purpose.
+        return formatter.format(date).replace("UTC", "Z")
+    }
 }
+
+@Deprecated("Please use SegmentInstant.now() instead", ReplaceWith("SegmentInstant.now()"))
+fun dateTimeNowString(): String {
+    return SegmentInstant.now()
+}

core/src/main/java/com/segment/analytics/kotlin/core/utilities/EventsFileManager.kt

@@ -135,7 +135,7 @@ class EventsFileManager(
         // close events array and batch object
 
 
-        val contents = """],"sentAt":"${dateTimeNowString()}","writeKey":"$writeKey"}"""
+        val contents = """],"sentAt":"${SegmentInstant.now()}","writeKey":"$writeKey"}"""
         writeToFile(contents.toByteArray(), file)
         file.renameTo(File(directory, file.nameWithoutExtension))
         os?.close()

core/src/test/kotlin/com/segment/analytics/kotlin/core/AnalyticsTests.kt

@@ -4,7 +4,7 @@ import com.segment.analytics.kotlin.core.platform.DestinationPlugin
 import com.segment.analytics.kotlin.core.platform.Plugin
 import com.segment.analytics.kotlin.core.platform.plugins.ContextPlugin
 import com.segment.analytics.kotlin.core.platform.plugins.SegmentDestination
-import com.segment.analytics.kotlin.core.utilities.dateTimeNowString
+import com.segment.analytics.kotlin.core.utilities.SegmentInstant
 import com.segment.analytics.kotlin.core.utils.StubPlugin
 import com.segment.analytics.kotlin.core.utils.TestRunPlugin
 import com.segment.analytics.kotlin.core.utils.clearPersistentStorage
@@ -28,7 +28,6 @@ import org.junit.jupiter.api.TestInstance
 import org.junit.jupiter.api.assertThrows
 import java.io.ByteArrayInputStream
 import java.net.HttpURLConnection
-import java.time.Instant
 import java.util.Date
 import java.util.UUID
 
@@ -50,10 +49,8 @@ class AnalyticsTests {
     private val testScope = TestScope(testDispatcher)
 
     init {
-        mockkStatic(Instant::class)
-        every { Instant.now() } returns Date(0).toInstant()
-        mockkStatic(::dateTimeNowString)
-        every { dateTimeNowString() } returns Date(0).toInstant().toString()
+        mockkObject(SegmentInstant)
+        every { SegmentInstant.now() } returns Date(0).toInstant().toString()
         mockkStatic(UUID::class)
         every { UUID.randomUUID().toString() } returns "qwerty-qwerty-123"
     }

core/src/test/kotlin/com/segment/analytics/kotlin/core/compat/JavaAnalyticsTest.kt

@@ -5,7 +5,7 @@ import com.segment.analytics.kotlin.core.platform.DestinationPlugin
 import com.segment.analytics.kotlin.core.platform.Plugin
 import com.segment.analytics.kotlin.core.platform.plugins.ContextPlugin
 import com.segment.analytics.kotlin.core.platform.plugins.SegmentDestination
-import com.segment.analytics.kotlin.core.utilities.dateTimeNowString
+import com.segment.analytics.kotlin.core.utilities.SegmentInstant
 import com.segment.analytics.kotlin.core.utils.StubPlugin
 import com.segment.analytics.kotlin.core.utils.TestRunPlugin
 import com.segment.analytics.kotlin.core.utils.mockHTTPClient
@@ -21,7 +21,6 @@ import org.junit.jupiter.api.Assertions.*
 import org.junit.jupiter.api.BeforeEach
 import org.junit.jupiter.api.Nested
 import org.junit.jupiter.api.Test
-import java.time.Instant
 import java.util.*
 import java.util.function.Consumer
 
@@ -43,10 +42,8 @@ internal class JavaAnalyticsTest {
     private val testScope = TestScope(testDispatcher)
 
     init {
-        mockkStatic(Instant::class)
-        every { Instant.now() } returns Date(0).toInstant()
-        mockkStatic(::dateTimeNowString)
-        every { dateTimeNowString() } returns Date(0).toInstant().toString()
+        mockkObject(SegmentInstant)
+        every { SegmentInstant.now() } returns Date(0).toInstant().toString()
         mockkStatic(UUID::class)
         every { UUID.randomUUID().toString() } returns "qwerty-qwerty-123"
         mockHTTPClient()

core/src/test/kotlin/com/segment/analytics/kotlin/core/utilities/DateTimeUtilsTest.kt

@@ -1,15 +1,27 @@
 package com.segment.analytics.kotlin.core.utilities
 
+import io.mockk.every
+import io.mockk.mockkConstructor
+import io.mockk.mockkObject
+import org.junit.jupiter.api.Assertions.assertEquals
 import org.junit.jupiter.api.Assertions.assertNotNull
 import org.junit.jupiter.api.Test
 import java.time.format.DateTimeFormatter.ISO_DATE_TIME
+import java.util.*
 
 class DateTimeUtilsTest {
 
     @Test
     fun `dateTimeNowString() produces a string in the correct ISO8601 format`() {
-        val dateTimeNowString = dateTimeNowString()
+        val dateTimeNowString = SegmentInstant.now()
         val date = ISO_DATE_TIME.parse(dateTimeNowString)
         assertNotNull(date)
     }
+
+    @Test
+    fun `dateTimeNowString() returns three digit seconds`() {
+        val date = Date(1700617928023L)
+        val dateTimeNowString = SegmentInstant.from(date)
+        assertEquals("2023-11-22T01:52:08.023Z", dateTimeNowString)
+    }
 }

core/src/test/kotlin/com/segment/analytics/kotlin/core/utilities/EventsFileManagerTest.kt

@@ -3,6 +3,7 @@ package com.segment.analytics.kotlin.core.utilities
 import com.segment.analytics.kotlin.core.TrackEvent
 import com.segment.analytics.kotlin.core.emptyJsonObject
 import io.mockk.every
+import io.mockk.mockkObject
 import io.mockk.mockkStatic
 import kotlinx.coroutines.test.runTest
 import kotlinx.serialization.encodeToString
@@ -24,11 +25,8 @@ internal class EventsFileManagerTest{
     private val kvStore = PropertiesFile(directory.parentFile, "123")
 
     init {
-        mockkStatic(Instant::class)
-        every { Instant.now() } returns Date(0).toInstant()
-
-        mockkStatic(::dateTimeNowString)
-        every { dateTimeNowString() } returns Date(0).toInstant().toString()
+        mockkObject(SegmentInstant)
+        every { SegmentInstant.now() } returns Date(0).toInstant().toString()
     }
 
     @BeforeEach