fix: last used format for device

sdk/src/main/java/io/customer/sdk/data/request/Device.kt

@@ -9,7 +9,7 @@ import java.util.*
 data class Device(
     @field:Json(name = "id") val token: String,
     val platform: String = "android",
-    val lastUsed: Date,
+    @field:Json(name = "last_used") val lastUsed: Date?, // nullable to cater for `lastUsed` field in older versions of the SDK
     val attributes: CustomAttributes
 )
 

sdk/src/sharedTest/java/io/customer/sdk/data/moshi/model/DeviceTest.kt

@@ -0,0 +1,79 @@
+package io.customer.sdk.data.moshi.model
+
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import io.customer.commontest.BaseTest
+import io.customer.sdk.data.request.Device
+import io.customer.sdk.util.JsonAdapter
+import java.util.Date
+import org.amshove.kluent.shouldBe
+import org.amshove.kluent.shouldBeEqualTo
+import org.amshove.kluent.shouldContain
+import org.amshove.kluent.shouldNotBe
+import org.junit.Test
+import org.junit.runner.RunWith
+
+@RunWith(AndroidJUnit4::class)
+class DeviceTest : BaseTest() {
+
+    private lateinit var adapter: JsonAdapter
+
+    override fun setup() {
+        super.setup()
+        adapter = di.jsonAdapter
+    }
+
+    @Test
+    fun parseDeviceJson_withInvalidLastUsedFormat_shouldStillDeserializeDevice() {
+        val givenTimestamp = 1683394080L
+
+        val json = """
+        {
+          "id": "123",
+          "platform": "android",
+          "lastUsed": $givenTimestamp,
+          "attributes": {}
+        }
+        """.trimIndent()
+
+        val device = jsonAdapter.fromJson<Device>(json)
+
+        device shouldNotBe null
+        device.lastUsed shouldBe null
+    }
+
+    @Test
+    fun parseDeviceJson_givenValidLastUsedFormat_expectDeserializeDeviceCorrectly() {
+        val givenTimestamp = 1683394080L
+
+        // Convert Unix timestamp to Date object for comparison
+        val expectedLastUsed = Date(givenTimestamp * 1000) // Multiply by 1000 to convert seconds to milliseconds
+
+        val json = """
+        {
+          "id": "123",
+          "platform": "android",
+          "last_used": $givenTimestamp,
+          "attributes": {}
+        }
+        """.trimIndent()
+
+        val device = jsonAdapter.fromJson<Device>(json)
+
+        device shouldNotBe null
+        device.lastUsed shouldBeEqualTo expectedLastUsed
+    }
+
+    @Test
+    fun serializeJson_verifyCorrectLastUsed() {
+        val device = Device(
+            token = "123",
+            platform = "android",
+            lastUsed = Date(),
+            attributes = emptyMap()
+        )
+
+        val json = jsonAdapter.toJson(device)
+
+        json shouldContain "\"last_used\""
+    }
+}