Add test of sync callbacks

bdk-android/lib/src/androidTest/kotlin/org/bitcoindevkit/Constants.kt

@@ -43,3 +43,4 @@ const val BIP84_TEST_RECEIVE_PATH_0 = "84h/1h/0h/0"
 val TEST_BIP84_DESCRIPTOR_0 = Descriptor("wpkh($TEST_EXTENDED_PRIVKEY_0/$BIP84_TEST_RECEIVE_PATH_0/*)", NetworkKind.TEST)
 
 const val ESPLORA_REGTEST_URL = "http://10.0.2.2:3002"
+const val ELECTRUM_REGTEST_URL = "tcp://10.0.2.2:60401"

bdk-android/lib/src/androidTest/kotlin/org/bitcoindevkit/SyncCallbacksTest.kt

@@ -0,0 +1,112 @@
+package org.bitcoindevkit
+
+import android.util.Log
+import kotlin.test.Test
+import kotlin.test.assertEquals
+import kotlin.test.assertTrue
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import org.junit.runner.RunWith
+
+@RunWith(AndroidJUnit4::class)
+class SyncCallbacksTest {
+    private val conn1: Persister = Persister.newInMemory()
+    private val conn2: Persister = Persister.newInMemory()
+
+    @Test
+    fun syncWithCallbackInspector() {
+        class SyncCallback : SyncScriptInspector {
+            var totalSynced = 0
+            var lastTotal: ULong = 0u
+
+            override fun inspect(script: Script, total: ULong) {
+                totalSynced++
+                lastTotal = total
+                println("Inspecting script $script ($totalSynced out of a total of $total)")
+            }
+        }
+
+        val wallet: Wallet = Wallet.createSingle(
+            descriptor = BIP86_DESCRIPTOR,
+            network = Network.REGTEST,
+            persister = conn1
+        )
+        wallet.revealAddressesTo(KeychainKind.EXTERNAL, 16u)
+        val electrumClient = ElectrumClient(ELECTRUM_REGTEST_URL)
+        val syncCallback = SyncCallback()
+        val syncRequest: SyncRequest = wallet.startSyncWithRevealedSpks()
+            .inspectSpks(syncCallback)
+            .build()
+
+        electrumClient.sync(
+            request = syncRequest,
+            batchSize = 10u,
+            fetchPrevTxouts = true
+        )
+
+        // Revealing addresses up to index 16 produces 17 revealed scripts (indices 0..16),
+        // each of which should be passed to the inspector exactly once.
+        assertEquals(17, syncCallback.totalSynced, "Inspector should have been called once per revealed script")
+        assertEquals(syncCallback.totalSynced.toULong(), syncCallback.lastTotal, "Number of inspected scripts should match the reported total")
+
+        // Logs
+        // Inspecting script OP_PUSHNUM_1 OP_PUSHBYTES_32 51af34057eae9eb1b27271904a78e7adef43a062a01c65e8ff775188d0180ffa (1 out of a total of 17)
+        // Inspecting script OP_PUSHNUM_1 OP_PUSHBYTES_32 089b36f682a8182b5beaae57fca90c7200f1269aa3deff27119e9c381a65328f (2 out of a total of 17)
+        // Inspecting script OP_PUSHNUM_1 OP_PUSHBYTES_32 2bd1aa8f1b4438bb302c5a5185e9f2541addbf58103eb2c32c7c5eb8d0e38147 (3 out of a total of 17)
+        // ...
+    }
+
+    @Test
+    fun fullScanWithCallbackInspector() {
+        class FullScanCallback : FullScanScriptInspector {
+            var totalSynced = 0
+            val keychainsSeen = mutableSetOf<KeychainKind>()
+
+            override fun inspect(
+                keychain: KeychainKind,
+                index: UInt,
+                script: Script
+            ) {
+                totalSynced++
+                keychainsSeen.add(keychain)
+                val address = Address.fromScript(script, Network.REGTEST)
+                Log.d("FullScanInspector", "[$keychain] index=$index address=$address (total scanned: $totalSynced)")
+            }
+        }
+
+        val wallet = Wallet(
+            descriptor = BIP84_DESCRIPTOR,
+            changeDescriptor = BIP84_CHANGE_DESCRIPTOR,
+            network = Network.REGTEST,
+            persister = conn2
+        )
+        val electrumClient = ElectrumClient(ELECTRUM_REGTEST_URL)
+        val fullScanCallback = FullScanCallback()
+        val fullScanRequest = wallet.startFullScan().inspectSpksForAllKeychains(fullScanCallback).build()
+
+        electrumClient.fullScan(
+            request = fullScanRequest,
+            stopGap = 25uL,
+            batchSize = 1u,
+            fetchPrevTxouts = true
+        )
+
+        // A full scan with a stop gap of 25 on an empty wallet inspects at least the first
+        // 25 scripts of each keychain before giving up, across both keychains.
+        assertEquals(
+            50,
+            fullScanCallback.totalSynced,
+            "Inspector should have been called 50 times"
+        )
+        assertEquals(
+            setOf(KeychainKind.EXTERNAL, KeychainKind.INTERNAL),
+            fullScanCallback.keychainsSeen,
+            "Both the external and internal keychains should be inspected"
+        )
+
+        // Logs
+        // [EXTERNAL] index=0 address=bcrt1p2xhngpt7460trvnjwxgy57884hh58grz5qwxt68lwagc35qcplaq2hks4m (total scanned: 1)
+        // [EXTERNAL] index=1 address=bcrt1ppzdnda5z4qvzkkl24etle2gvwgq0zf5650007fc3n6wrsxn9x28sshtggg (total scanned: 2)
+        // [EXTERNAL] index=2 address=bcrt1p90g64rcmgsutkvpvtfgct60j2sddm06czqlt9sev030t358rs9rsjppelk (total scanned: 3)
+        // ...
+    }
+}