Generate test fixture dates that are serializable and in the future

stream-chat-android-client/src/test/java/io/getstream/chat/android/client/internal/offline/repository/database/converter/ReminderInfoConverterTest.kt

@@ -0,0 +1,71 @@
+/*
+ * Copyright (c) 2014-2026 Stream.io Inc. All rights reserved.
+ *
+ * Licensed under the Stream License;
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    https://github.com/GetStream/stream-chat-android/blob/main/LICENSE
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.getstream.chat.android.client.internal.offline.repository.database.converter
+
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import io.getstream.chat.android.client.internal.offline.repository.database.converter.internal.ReminderInfoConverter
+import io.getstream.chat.android.client.internal.offline.repository.domain.message.internal.ReminderInfoEntity
+import io.getstream.chat.android.randomDate
+import io.getstream.chat.android.randomDateOrNull
+import org.amshove.kluent.shouldBeEqualTo
+import org.junit.Test
+import org.junit.runner.RunWith
+import java.util.Date
+
+/**
+ * Runs under Robolectric because the dates are serialised by the API 26+ formatter, which is stricter about the year
+ * than the [java.text.SimpleDateFormat] fallback used below it.
+ */
+@RunWith(AndroidJUnit4::class)
+internal class ReminderInfoConverterTest {
+
+    private val converter = ReminderInfoConverter()
+
+    @Test
+    fun `a reminder built from the date fixtures survives the round trip`() {
+        repeat(ROUNDS) {
+            val reminder = ReminderInfoEntity(
+                remindAt = randomDateOrNull(),
+                createdAt = randomDate(),
+                updatedAt = randomDate(),
+            )
+
+            converter.stringToReminderInfo(converter.reminderInfoToString(reminder)) shouldBeEqualTo reminder
+        }
+    }
+
+    @Test
+    fun `a reminder at the last serializable instant survives the round trip`() {
+        // Guards the upper bound the date fixtures generate up to: past it the year no longer fits the wire format,
+        // and a reminder comes back holding a different date, or fails to be read back at all.
+        val lastSerializable = Date(LAST_SERIALIZABLE_DATE_MILLIS)
+        val reminder = ReminderInfoEntity(
+            remindAt = lastSerializable,
+            createdAt = lastSerializable,
+            updatedAt = lastSerializable,
+        )
+
+        converter.stringToReminderInfo(converter.reminderInfoToString(reminder)) shouldBeEqualTo reminder
+    }
+
+    private companion object {
+        // Enough draws that a fixture generating unserializable dates again fails here, rather than
+        // intermittently somewhere downstream.
+        const val ROUNDS = 5_000
+        const val LAST_SERIALIZABLE_DATE_MILLIS = 253_402_300_799_999L // 9999-12-31T23:59:59.999Z
+    }
+}

stream-chat-android-core/src/test/java/io/getstream/chat/android/RandomDateTest.kt

@@ -0,0 +1,64 @@
+/*
+ * Copyright (c) 2014-2026 Stream.io Inc. All rights reserved.
+ *
+ * Licensed under the Stream License;
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    https://github.com/GetStream/stream-chat-android/blob/main/LICENSE
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.getstream.chat.android
+
+import org.amshove.kluent.shouldBeNull
+import org.junit.jupiter.api.Test
+import java.util.Date
+
+/**
+ * The two properties the rest of the suite leans on. Both have broken before, and because the generator is random,
+ * breaking either shows up as an unrelated test failing once in a few hundred CI runs rather than as a failure here.
+ */
+internal class RandomDateTest {
+
+    @Test
+    fun `a generated date is always in the future`() {
+        // Production code that keeps only future dates, live locations for one, drops a fixture date that is already
+        // in the past, leaving the test asserting on an empty result.
+        val now = Date()
+
+        val past = List(ROUNDS) { randomDate() }.filter { it.before(now) }
+
+        past.firstOrNull().shouldBeNull()
+    }
+
+    @Test
+    fun `a generated date is always serializable`() {
+        // The ISO-8601 formatter writes a four digit year, so a later date is written as a different date, or as one
+        // that cannot be read back at all.
+        val lastSerializable = Date(LAST_SERIALIZABLE_DATE_MILLIS)
+
+        val unserializable = List(ROUNDS) { randomDate() }.filter { it.after(lastSerializable) }
+
+        unserializable.firstOrNull().shouldBeNull()
+    }
+
+    @Test
+    fun `a date generated after another one is serializable too`() {
+        val lastSerializable = Date(LAST_SERIALIZABLE_DATE_MILLIS)
+
+        val unserializable = List(ROUNDS) { randomDateAfter(randomDate()) }.filter { it.after(lastSerializable) }
+
+        unserializable.firstOrNull().shouldBeNull()
+    }
+
+    private companion object {
+        const val ROUNDS = 100_000
+        const val LAST_SERIALIZABLE_DATE_MILLIS = 253_402_300_799_999L // 9999-12-31T23:59:59.999Z
+    }
+}

stream-chat-android-core/src/testFixtures/kotlin/io/getstream/chat/android/Mother.kt

@@ -773,10 +773,23 @@ public fun randomFiles(
     creationFunction: (Int) -> File = { randomFile() },
 ): List<File> = (1..size).map(creationFunction)
 
+/**
+ * The window generated dates are drawn from.
+ *
+ * The upper bound is the last instant the SDK can serialise: the ISO-8601 formatter writes a four digit year, so
+ * anything past year 9999 is written as a different date, or as one that cannot be read back at all.
+ *
+ * The lower bound keeps generated dates in the future, which is what callers already relied on. Drawing from the whole
+ * positive `Long` range put every date millions of years ahead, so production code that keeps only future dates, live
+ * locations for one, never saw a generated date fall behind the clock. Use [randomDateBefore] for a date in the past.
+ */
+private const val MIN_GENERATED_DATE_MILLIS: Long = 32_503_680_000_000L // 3000-01-01T00:00:00.000Z
+private const val MAX_GENERATED_DATE_MILLIS: Long = 253_402_300_799_999L // 9999-12-31T23:59:59.999Z
+
 public fun randomDateOrNull(): Date? = randomDate().takeIf { randomBoolean() }
-public fun randomDate(): Date = Date(positiveRandomLong())
+public fun randomDate(): Date = Date(randomLongBetween(MIN_GENERATED_DATE_MILLIS, MAX_GENERATED_DATE_MILLIS))
 public fun randomDateBefore(date: Date): Date = Date(date.time - positiveRandomInt())
-public fun randomDateAfter(date: Date): Date = Date(randomLongBetween(date.time))
+public fun randomDateAfter(date: Date): Date = Date(randomLongBetween(date.time, MAX_GENERATED_DATE_MILLIS))
 
 public fun createDate(
     year: Int = positiveRandomInt(),