test: add offline tests for wallet new_or_load method

bdk-jvm/lib/src/test/kotlin/org/bitcoindevkit/OfflinePersistenceTest.kt

@@ -0,0 +1,45 @@
+package org.bitcoindevkit
+
+import kotlin.test.Test
+import kotlin.test.assertEquals
+
+class OfflinePersistenceTest {
+    private val persistenceFilePath = run {
+        val currentDirectory = System.getProperty("user.dir")
+        val dbFileName = "pre_existing_wallet_persistence_test.sqlite"
+        "$currentDirectory/src/test/resources/$dbFileName"
+    }
+    private val descriptor: Descriptor = Descriptor(
+        "wpkh(tprv8ZgxMBicQKsPf2qfrEygW6fdYseJDDrVnDv26PH5BHdvSuG6ecCbHqLVof9yZcMoM31z9ur3tTYbSnr1WBqbGX97CbXcmp5H6qeMpyvx35B/84h/1h/0h/0/*)",
+        Network.SIGNET
+    )
+    private val changeDescriptor: Descriptor = Descriptor(
+        "wpkh(tprv8ZgxMBicQKsPf2qfrEygW6fdYseJDDrVnDv26PH5BHdvSuG6ecCbHqLVof9yZcMoM31z9ur3tTYbSnr1WBqbGX97CbXcmp5H6qeMpyvx35B/84h/1h/0h/1/*)",
+        Network.SIGNET
+    )
+
+    @Test
+    fun testPersistence() {
+        val sqliteStore: SqliteStore = SqliteStore(persistenceFilePath)
+        val initialChangeSet: ChangeSet? = sqliteStore.read()
+        requireNotNull(initialChangeSet) { "ChangeSet should not be null after loading a valid database" }
+
+        val wallet: Wallet = Wallet.newOrLoad(
+            descriptor,
+            changeDescriptor,
+            initialChangeSet,
+            Network.SIGNET,
+        )
+        val addressInfo: AddressInfo = wallet.revealNextAddress(KeychainKind.EXTERNAL)
+        println("Address: $addressInfo")
+
+        assertEquals(
+            expected = 7u,
+            actual = addressInfo.index,
+        )
+        assertEquals(
+            expected = "tb1qan3lldunh37ma6c0afeywgjyjgnyc8uz975zl2",
+            actual = addressInfo.address.toString(),
+        )
+    }
+}