test(app): add headless ViewModel, CLI and localization tests

ViewModels run on Avalonia.Headless: wizard flows, password and file-lock
handling, seed and private-key reveal gating, contacts, settings, sync and
send against the fake server. The CLI entry point is invoked in-process
end to end. Localization checks cover the 7 languages, placeholders and
keys used in sources. Internal seams (UpdateCheck, ProfileOverride) keep
the tests offline.

tests/PalladiumWallet.Tests/App/VmTestBase.cs

@@ -0,0 +1,114 @@
+using Avalonia.Threading;
+using NBitcoin;
+using PalladiumWallet.App.Localization;
+using PalladiumWallet.App.ViewModels;
+using PalladiumWallet.Core.Chain;
+using PalladiumWallet.Core.Crypto;
+using PalladiumWallet.Core.Net;
+using PalladiumWallet.Core.Spv;
+using PalladiumWallet.Core.Storage;
+using PalladiumWallet.Core.Wallet;
+using PalladiumWallet.Tests.Net;
+
+namespace PalladiumWallet.Tests.App;
+
+/// <summary>
+/// Headless tests of the single application ViewModel. Everything is sandboxed: the data
+/// root is a temp folder, the saved server points at an in-process FakeElectrumServer (so the
+/// auto-connect never reaches a real server) and the GitHub update check is stubbed.
+/// </summary>
+[Collection("AppPaths")] // static AppPaths / Loc / update-check seam
+public abstract class VmTestBase : IDisposable
+{
+    protected const string Mnemonic =
+        "abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon about";
+
+    private readonly string _root = Path.Combine(Path.GetTempPath(), $"plm-vm-{Guid.NewGuid()}");
+    private readonly string? _savedOverride = AppPaths.OverrideDataRoot;
+    private readonly Func<string, Task<LatestRelease?>> _savedUpdateCheck = MainWindowViewModel.UpdateCheck;
+    protected readonly FakeElectrumServer _server = new();
+
+    protected VmTestBase()
+    {
+        AppPaths.OverrideDataRoot = _root;
+        MainWindowViewModel.UpdateCheck = _ => Task.FromResult<LatestRelease?>(null);
+        // No bootstrap servers: the only reachable server is the in-process fake, so the
+        // VM's connect/reconnect loops can never touch a real indexing server.
+        MainWindowViewModel.ProfileOverride = ChainProfiles.Mainnet with { BootstrapServers = [] };
+        new AppConfig { LastServerHost = _server.Host, LastServerPort = _server.Port, LastServerUseSsl = false }
+            .Save(AppPaths.ConfigPath());
+    }
+
+    public void Dispose()
+    {
+        MainWindowViewModel.UpdateCheck = _savedUpdateCheck;
+        // ProfileOverride is intentionally left in place: ViewModels created by a test keep their
+        // keep-alive timers running, and restoring the real profile would let them reconnect to
+        // the real bootstrap servers after the test is over. Nothing else in the suite uses it.
+        AppPaths.OverrideDataRoot = _savedOverride;
+        Loc.SwitchTo("en");
+        _server.DisposeAsync().AsTask().GetAwaiter().GetResult();
+        try { Directory.Delete(_root, recursive: true); } catch { /* best effort */ }
+    }
+
+    protected static async Task Eventually(Func<bool> condition, int timeoutMs = 10_000)
+    {
+        for (var waited = 0; !condition(); waited += 20)
+        {
+            Assert.True(waited < timeoutMs, "condition not reached in time");
+            Dispatcher.UIThread.RunJobs();
+            await Task.Delay(20);
+        }
+    }
+
+    protected static void RestoreFlow(MainWindowViewModel vm, string mnemonic, string? password, string? name = null)
+    {
+        vm.WizardStartRestoreCommand.Execute(null);
+        vm.MnemonicInput = mnemonic;
+        vm.WizardNextFromWordsCommand.Execute(null);
+        vm.WizardNextFromPassphraseCommand.Execute(null);
+        vm.WizardNextFromScriptTypeCommand.Execute(null);
+        vm.EncryptWallet = password is not null;
+        vm.PasswordInput = vm.ConfirmPasswordInput = password ?? "";
+        vm.WalletNameInput = name ?? "";
+        vm.CreateOrRestoreCommand.Execute(null);
+    }
+
+    protected static Mnemonic ParseMnemonic()
+    {
+        Assert.True(Bip39.TryParse(Mnemonic, out var m));
+        return m!;
+    }
+
+    protected (Transaction Funding, string TxHex) WireFundedChain(BitcoinAddress to, long sats)
+    {
+        var net = PalladiumNetworks.Mainnet;
+        var tx = net.CreateTransaction();
+        tx.Inputs.Add(new TxIn(new OutPoint(uint256.One, 0)));
+        tx.Outputs.Add(Money.Satoshis(sats), to);
+        var txid = tx.GetHash();
+        var scripthash = Scripthash.FromAddress(to);
+
+        string Header(uint256 root, int h)
+        {
+            var header = net.Consensus.ConsensusFactory.CreateBlockHeader();
+            header.HashPrevBlock = uint256.Zero;
+            header.HashMerkleRoot = root;
+            header.BlockTime = DateTimeOffset.FromUnixTimeSeconds(1_700_000_000 + h);
+            header.Bits = new Target(0x1d00ffffu);
+            header.Nonce = (uint)h;
+            return Convert.ToHexString(header.ToBytes()).ToLowerInvariant();
+        }
+
+        _server.Handle("blockchain.headers.subscribe", _ => new { height = 200, hex = Header(uint256.One, 200) });
+        _server.Handle("blockchain.scripthash.subscribe", _ => null);
+        _server.Handle("blockchain.scripthash.get_history", p =>
+            p[0].GetString() == scripthash ? new[] { new { tx_hash = txid.ToString(), height = 100 } } : Array.Empty<object>());
+        _server.Handle("blockchain.transaction.get", _ => tx.ToHex());
+        _server.Handle("blockchain.transaction.get_merkle",
+            _ => new { block_height = 100, pos = 0, merkle = Array.Empty<string>() });
+        _server.Handle("blockchain.block.header", _ => Header(txid, 100));
+        _server.Handle("blockchain.block.headers", _ => new { count = 0, hex = "" });
+        return (tx, tx.ToHex());
+    }
+}