test: verify VssBackupClient handles missing mnemonic gracefully

Author: piotr-iohk

app/src/test/java/to/bitkit/data/backup/VssBackupClientTest.kt

@@ -0,0 +1,72 @@
+package to.bitkit.data.backup
+
+import kotlinx.coroutines.runBlocking
+import org.junit.Before
+import org.junit.Test
+import org.mockito.kotlin.any
+import org.mockito.kotlin.mock
+import org.mockito.kotlin.never
+import org.mockito.kotlin.verify
+import org.mockito.kotlin.whenever
+import to.bitkit.data.keychain.Keychain
+import to.bitkit.test.BaseUnitTest
+import kotlin.test.assertFalse
+import kotlin.test.assertTrue
+
+class VssBackupClientTest : BaseUnitTest() {
+
+    private lateinit var sut: VssBackupClient
+
+    private val vssStoreIdProvider = mock<VssStoreIdProvider>()
+    private val keychain = mock<Keychain>()
+
+    @Before
+    fun setUp() = runBlocking {
+        sut = VssBackupClient(
+            ioDispatcher = testDispatcher,
+            vssStoreIdProvider = vssStoreIdProvider,
+            keychain = keychain,
+        )
+    }
+
+    @Test
+    fun `setup returns false when mnemonic is not available`() = test {
+        whenever(keychain.loadString(Keychain.Key.BIP39_MNEMONIC.name)).thenReturn(null)
+
+        val result = sut.setup()
+
+        assertFalse(result)
+    }
+
+    @Test
+    fun `setup does not call vssStoreIdProvider when mnemonic is not available`() = test {
+        whenever(keychain.loadString(Keychain.Key.BIP39_MNEMONIC.name)).thenReturn(null)
+
+        sut.setup()
+
+        verify(vssStoreIdProvider, never()).getVssStoreId(any())
+    }
+
+    @Test
+    fun `setup checks mnemonic before proceeding with vss initialization`() = test {
+        val testMnemonic = "abandon abandon abandon abandon abandon abandon " +
+            "abandon abandon abandon abandon abandon about"
+        whenever(keychain.loadString(Keychain.Key.BIP39_MNEMONIC.name)).thenReturn(testMnemonic)
+        whenever(vssStoreIdProvider.getVssStoreId(any())).thenReturn("test-store-id")
+
+        // Setup will fail on native VSS calls, but we verify we passed the mnemonic check
+        runCatching { sut.setup() }
+
+        verify(vssStoreIdProvider).getVssStoreId(any())
+    }
+
+    @Test
+    fun `setup can be called multiple times when mnemonic not available`() = test {
+        whenever(keychain.loadString(Keychain.Key.BIP39_MNEMONIC.name)).thenReturn(null)
+
+        // Multiple calls should all return false without crashing
+        assertFalse(sut.setup())
+        assertFalse(sut.setup())
+        assertFalse(sut.setup())
+    }
+}