DodoSSH/tests/DodoSSH.Client.App.Tests/VaultSharingTests.cs

using DodoSSH.Client.Session;
// FakeDeviceKeyStore is compiled into this assembly from a source link and keeps its original namespace;
// see the csproj for why it is shared rather than reimplemented.
using DodoSSH.Client.Session.Tests;
using DodoSSH.Client.Shell.ViewModels;
using DodoSSH.Client.Ssh;
using DodoSSH.Client.Storage;
using DodoSSH.Client.Terminal;
using DodoSSH.Contracts;
using DodoSSH.Crypto;

namespace DodoSSH.Client.App.Tests;

/// <summary>
/// Vaults, from the side that holds the keys: make one, add somebody, and wrap its key to them.
/// </summary>
/// <remarks>
/// <para>
/// The reason this suite exists rather than leaving sharing to the server's own tests is that the
/// interesting half is not on the server. Adding a member is a row; <b>sharing is a decision the client
/// makes about whether to trust a public key the server just handed it</b>, and that decision is what
/// stands between an end-to-end encrypted vault and one the operator can read by answering a directory
/// lookup with a key of their own.
/// </para>
/// <para>
/// So the fake server keeps a real key log — chained with the same <c>KeyLogChain</c> the server uses —
/// and can be told to corrupt it. A test that only ever saw a well-formed log would be checking that
/// sharing works, not that verification does.
/// </para>
/// <para>
/// It was <c>TeamSharingTests</c>, and the screen it drives stopped being about teams: a vault is what
/// gets made and named, and the membership list behind it is made with it. The team is still what the
/// server authorises against, which is why the assertions about roles, hand-over and invitations are all
/// still here — they are the same operations, reached through the vault they apply to.
/// </para>
/// </remarks>
public sealed class VaultSharingTests : IAsyncLifetime
{
    private const string Passphrase = "a sufficiently long passphrase";

    private static readonly Argon2Profile CheapProfile =
        Argon2Profile.FromStoredParameters(memoryKibibytes: 8 * 1024, passes: 1, parallelism: 1);

    private readonly FakeVaultServer server = new();
    private readonly FakeSshConnectionFactory ssh = new();

    private string directory = null!;
    private ClientCacheFactory caches = null!;
    private TerminalWorkspace workspace = null!;
    private VaultKnownHostStore knownHosts = null!;
    private FakeDeviceKeyStore deviceKeys = null!;
    private MainWindowViewModel shell = null!;

    private static CancellationToken Token => TestContext.Current.CancellationToken;

    /// <inheritdoc />
    public ValueTask InitializeAsync()
    {
        directory = Path.Combine(Path.GetTempPath(), $"dodossh-vaults-{Guid.CreateVersion7():N}");

        var paths = new ClientPaths(directory);

        caches = ClientCacheFactory.ForFile(paths.CacheFile);
        knownHosts = new VaultKnownHostStore();
        deviceKeys = new FakeDeviceKeyStore();

        workspace = new TerminalWorkspace(
            new InMemoryTerminalAssetProvider(
                new Dictionary<string, TerminalAsset>(StringComparer.Ordinal)),
            ssh,
            TimeProvider.System);

        shell = new MainWindowViewModel(
            paths,
            caches,
            workspace,
            knownHosts,
            deviceKeys,
            (_, _) => Task.FromResult<IVaultServer>(server),
            TimeProvider.System,
            NSubstitute.Substitute.For<ISftpSessionFactory>(),
            CheapProfile);

        return ValueTask.CompletedTask;
    }

    /// <inheritdoc />
    public async ValueTask DisposeAsync()
    {
        await shell.DisposeAsync();
        knownHosts.Close();
        await workspace.DisposeAsync();
        caches.Dispose();

        try
        {
            Directory.Delete(directory, recursive: true);
        }
        catch (IOException)
        {
            // A cache file the process has not finished releasing. The directory is under the temp path
            // and named per run, so leaving it costs a few kilobytes and never collides.
        }
    }

    /// <remarks>
    /// The whole point of a shared vault, in one test. Note what the status line says after the add and
    /// before the share: adding somebody grants them nothing readable, and the interface has to say so
    /// rather than let a user believe the credential is already with their colleague.
    /// </remarks>
    [Fact]
    public async Task CreatingAVaultAndSharingIt_WrapsTheKeyToTheOtherMember()
    {
        await UnlockedAsync();

        var vaults = shell.Vaults;
        var colleague = server.AddAccount("bob@example.com", "Bob Example");

        await CreateVaultAsync(vaults, "Platform secrets");

        vaults.InviteEmail = "bob@example.com";
        await vaults.AddMemberCommand.ExecuteAsync(null);

        vaults.Members.Count.ShouldBe(2, vaults.Status);
        vaults.Status.ShouldContain("cannot read anything yet");

        vaults.SelectedMember = vaults.Members.Single(member => member.UserId == colleague);

        await vaults.ShareVaultCommand.ExecuteAsync(null);

        var vaultId = vaults.SelectedVault!.VaultId;

        server.IssuedGrants.ShouldContainKey((vaultId, colleague));
        vaults.Status.ShouldContain("Shared");

        // The one thing verification cannot promise, said in the same breath as the success.
        vaults.Status.ShouldContain("fingerprint", Case.Insensitive);
    }

    /// <remarks>
    /// <para>
    /// The test this whole design exists for. A server that wants to read a shared vault only has to
    /// answer one directory lookup with a key it holds the private half of — so the client reads the
    /// append-only key log, verifies its chain, and refuses to wrap anything unless the key it was
    /// offered is in there unchanged.
    /// </para>
    /// <para>
    /// Nothing may be sent. A refusal that still issued the grant, or that issued it on a retry, would be
    /// worse than no check at all, because the interface would have said it was verified.
    /// </para>
    /// </remarks>
    [Fact]
    public async Task ATamperedKeyLog_StopsTheShareRatherThanWarningAboutIt()
    {
        await UnlockedAsync();

        var vaults = shell.Vaults;
        var colleague = server.AddAccount("mallory@example.com", "Mallory Example");

        await CreateVaultAsync(vaults, "Platform secrets");

        vaults.InviteEmail = "mallory@example.com";
        await vaults.AddMemberCommand.ExecuteAsync(null);

        vaults.SelectedMember = vaults.Members.Single(member => member.UserId == colleague);

        server.CorruptKeyLog = true;

        await vaults.ShareVaultCommand.ExecuteAsync(null);

        server.IssuedGrants.ShouldBeEmpty();
        vaults.Status.ShouldContain("Did not share");
        vaults.Status.ShouldContain("key log");
    }

    /// <remarks>
    /// A vault created here is usable here, without a relock. The key was generated in this process, so
    /// making the user lock and unlock to reach the vault they just made would be asking them to work
    /// around bookkeeping.
    /// </remarks>
    [Fact]
    public async Task AVaultCreatedHere_IsImmediatelyReadableAndWritable()
    {
        await UnlockedAsync();

        var vaults = shell.Vaults;

        await CreateVaultAsync(vaults, "Platform secrets");

        var vaultId = vaults.SelectedVault!.VaultId;
        var session = shell.Vault!.Session;

        session.ReadableVaults.Select(vault => vault.VaultId).ShouldContain(vaultId);

        // And it is offered as somewhere to file a new item, which is what makes it worth having.
        await shell.Vault.LoadAsync(Token);

        shell.Vault.TargetVaults.Select(choice => choice.VaultId).ShouldContain(vaultId);
        shell.Vault.HasVaultChoice.ShouldBeTrue();
    }

    /// <remarks>
    /// Making a vault makes exactly one membership list, and this is the assertion that the two-step create
    /// has not started leaking them: the screen no longer offers to make one on its own, so a second one
    /// per vault would be invisible in the interface and visible only to an operator.
    /// </remarks>
    [Fact]
    public async Task CreatingAVault_MakesOneMembershipListWithTheCallerAsItsOwner()
    {
        await UnlockedAsync();

        var vaults = shell.Vaults;

        await CreateVaultAsync(vaults, "Platform secrets");

        server.TeamCreates.ShouldBe(1);

        var row = vaults.Vaults.Single(
            vault => string.Equals(vault.Name, "Platform secrets", StringComparison.Ordinal));

        row.IsShared.ShouldBeTrue("a vault made here is one other people can be added to");
        row.IsOwned.ShouldBeTrue(vaults.Status);
        row.SharedWithOtherVaults.ShouldBe(0, "it was made with a membership list of its own");

        vaults.Members.ShouldHaveSingleItem().Role.ShouldBe("OWNER");
    }

    /// <remarks>
    /// The personal vault is in the list, is marked as the one thing it is, and offers nothing to share:
    /// the server refuses a grant on one outright, so a screen that let somebody try would be sending them
    /// at a refusal.
    /// </remarks>
    [Fact]
    public async Task ThePersonalVault_IsListedAndCannotBeSharedWithAnybody()
    {
        await UnlockedAsync();

        var vaults = shell.Vaults;

        await vaults.LoadAsync(Token);

        var personal = vaults.Vaults.ShouldHaveSingleItem();

        personal.IsPersonal.ShouldBeTrue();
        personal.IsShared.ShouldBeFalse();
        personal.RoleLabel.ShouldBe("PERSONAL");

        vaults.SelectedVault = personal;
        vaults.SelectedIsShared.ShouldBeFalse();

        vaults.InviteEmail = "bob@example.com";
        await vaults.AddMemberCommand.ExecuteAsync(null);

        vaults.Members.ShouldBeEmpty();
        vaults.Status.ShouldContain("cannot be shared");
    }

    /// <remarks>
    /// Filing into a shared vault has to be chosen and has to stick. The bug this guards is the obvious
    /// one: an editor that read the picker at save time rather than at open time, so changing the picker
    /// with a half-typed host on screen would move it.
    /// </remarks>
    [Fact]
    public async Task AHostFiledIntoASharedVault_StaysThere()
    {
        await UnlockedAsync();

        var vaults = shell.Vaults;

        await CreateVaultAsync(vaults, "Platform secrets");

        var vault = shell.Vault!;
        var sharedVaultId = vaults.SelectedVault!.VaultId;

        await vault.LoadAsync(Token);

        vault.SelectedTargetVault =
            vault.TargetVaults.Single(choice => choice.VaultId == sharedVaultId);

        vault.NewHostCommand.Execute(null);
        vault.EditorLabel = "prod-db";
        vault.EditorHostname = "db.internal";
        vault.EditorUsername = "deploy";

        // Moved back after the editor opened. The host must still land in the shared vault: the keychain
        // screen's picker seeds the editor's and stops mattering from there.
        vault.SelectedTargetVault =
            vault.TargetVaults.First(choice => choice.VaultId != sharedVaultId);

        await vault.SaveHostCommand.ExecuteAsync(null);

        var row = vault.Hosts.Single(
            host => string.Equals(host.Label, "prod-db", StringComparison.Ordinal));
        row.VaultId.ShouldBe(sharedVaultId);
    }

    /// <remarks>
    /// <para>
    /// The picker the host editor grew, and the thing it is for: choosing at the moment a host is created,
    /// on the form the host is being typed into, rather than through a standing preference on another
    /// screen.
    /// </para>
    /// <para>
    /// It is asserted from the editor's own selection rather than the keychain screen's, because the two
    /// are deliberately separate — moving one must not move the other.
    /// </para>
    /// </remarks>
    [Fact]
    public async Task TheHostEditorChoosesItsOwnVault_WithoutMovingTheKeychainScreensPicker()
    {
        await UnlockedAsync();

        var vaults = shell.Vaults;

        await CreateVaultAsync(vaults, "Platform secrets");

        var vault = shell.Vault!;
        var sharedVaultId = vaults.SelectedVault!.VaultId;

        await vault.LoadAsync(Token);

        vault.NewHostCommand.Execute(null);

        vault.ShowsEditorVaultChoice.ShouldBeTrue("there are two vaults to choose between");

        var personal = vault.SelectedTargetVault!;

        vault.EditorSelectedVault =
            vault.EditorVaultChoices.Single(choice => choice.VaultId == sharedVaultId);

        vault.EditorLabel = "prod-db";
        vault.EditorHostname = "db.internal";

        await vault.SaveHostCommand.ExecuteAsync(null);

        vault.Hosts
            .Single(host => string.Equals(host.Label, "prod-db", StringComparison.Ordinal))
            .VaultId
            .ShouldBe(sharedVaultId);

        vault.SelectedTargetVault.ShouldBe(
            personal, "the editor's picker is the host's, not the screen's standing preference");
    }

    /// <remarks>
    /// An existing host is not offered the picker at all. Moving an item between vaults is a delete and a
    /// retype — they are encrypted under different keys — so a control that appeared to offer it would be
    /// offering something no layer below can do.
    /// </remarks>
    [Fact]
    public async Task EditingAnExistingHost_DoesNotOfferToMoveItBetweenVaults()
    {
        await UnlockedAsync();

        var vaults = shell.Vaults;

        await CreateVaultAsync(vaults, "Platform secrets");

        var vault = shell.Vault!;

        await vault.LoadAsync(Token);

        vault.NewHostCommand.Execute(null);
        vault.EditorLabel = "prod-db";
        vault.EditorHostname = "db.internal";
        await vault.SaveHostCommand.ExecuteAsync(null);

        vault.SelectedHost = vault.Hosts.Single(
            host => string.Equals(host.Label, "prod-db", StringComparison.Ordinal));

        vault.EditSelectedHostCommand.Execute(null);

        vault.IsEditing.ShouldBeTrue(vault.Status);
        vault.ShowsEditorVaultChoice.ShouldBeFalse("an item cannot be moved between vaults");
    }

    /// <remarks>
    /// The mirror image of the host test above, and it goes the other way on purpose. A host filed into a
    /// shared vault has to stay there, because hosts are read across every readable vault and so come back.
    /// Tags are not — the editable list is the active vault's alone, like groups and buckets — so a tag
    /// filed anywhere else would be created, pushed, reported as added and then invisible, with nothing on
    /// the keychain screen able to rename or delete it and no active-vault switcher to go and find it with.
    /// </remarks>
    [Fact]
    public async Task ATagIgnoresTheTargetPicker_BecauseItsListOnlyEverShowsOneVault()
    {
        await UnlockedAsync();

        var vaults = shell.Vaults;

        await CreateVaultAsync(vaults, "Platform secrets");

        var sharedVaultId = vaults.SelectedVault!.VaultId;
        var vault = shell.Vault!;

        await vault.LoadAsync(Token);

        vault.HasVaultChoice.ShouldBeTrue("this test is meaningless with one vault");

        vault.SelectedTargetVault = vault.TargetVaults.Single(
            choice => choice.VaultId == sharedVaultId);

        vault.NewTagCommand.Execute(null);
        vault.TagEditorLabel = "eu-west-1";
        await vault.SaveTagCommand.ExecuteAsync(null);

        vault.Tags.ShouldHaveSingleItem().Label
            .ShouldBe("eu-west-1", "a tag that is not in the list is a tag nothing can reach");
    }

    /// <remarks>
    /// The screen's answer to "who can actually open this". Asserted after a share rather than before,
    /// because an empty list proves nothing about whether the call was made.
    /// </remarks>
    [Fact]
    public async Task SelectingAVault_ListsWhoHoldsAKeyToIt()
    {
        await UnlockedAsync();

        var vaults = shell.Vaults;
        var colleague = server.AddAccount("bob@example.com", "Bob Example");

        await CreateVaultAsync(vaults, "Platform secrets");

        vaults.InviteEmail = "bob@example.com";
        await vaults.AddMemberCommand.ExecuteAsync(null);

        vaults.SelectedMember = vaults.Members.Single(member => member.UserId == colleague);

        await vaults.ShareVaultCommand.ExecuteAsync(null);

        var holder = vaults.Grants.ShouldHaveSingleItem();

        holder.UserId.ShouldBe(colleague);
        holder.IsLive.ShouldBeTrue(vaults.Status);
        holder.State.ShouldBe("holds a key");
    }

    /// <remarks>
    /// A role change is authorization only. The status line has to say so, because the obvious reading
    /// of "demoted to viewer" is that they can no longer read the vault — and they still can, with the
    /// key they were already wrapped. Withdrawing that is a separate act.
    /// </remarks>
    [Fact]
    public async Task ChangingAMembersRole_SaysItDoesNotTakeBackTheKeyTheyHold()
    {
        await UnlockedAsync();

        var vaults = shell.Vaults;
        var colleague = server.AddAccount("bob@example.com", "Bob Example");

        await CreateVaultAsync(vaults, "Platform secrets");

        vaults.InviteEmail = "bob@example.com";
        await vaults.AddMemberCommand.ExecuteAsync(null);

        vaults.SelectedMember = vaults.Members.Single(member => member.UserId == colleague);

        await vaults.ChangeRoleCommand.ExecuteAsync(TeamMemberRole.Admin);

        vaults.Members.Single(member => member.UserId == colleague).Role.ShouldBe("ADMIN");
        vaults.Status.ShouldContain("does not withdraw a vault key");
    }

    /// <remarks>
    /// The owner's role is the one that cannot be changed this way, and the interface has to refuse it
    /// itself rather than letting the server do it: a button that produced a server error would be
    /// reporting a rule the screen already knew.
    /// </remarks>
    [Fact]
    public async Task MakingSomebodyOwnerThroughTheRolePicker_IsRefusedAndPointsAtHandingOver()
    {
        await UnlockedAsync();

        var vaults = shell.Vaults;
        var colleague = server.AddAccount("bob@example.com", "Bob Example");

        await CreateVaultAsync(vaults, "Platform secrets");

        vaults.InviteEmail = "bob@example.com";
        await vaults.AddMemberCommand.ExecuteAsync(null);

        vaults.SelectedMember = vaults.Members.Single(member => member.UserId == colleague);

        await vaults.ChangeRoleCommand.ExecuteAsync(TeamMemberRole.Owner);

        vaults.Members.Single(member => member.UserId == colleague).Role.ShouldBe("MEMBER");
        vaults.Status.ShouldContain("HAND OVER");
    }

    /// <remarks>
    /// <para>
    /// Both halves, because a transfer that only promoted the recipient would leave the vault owned
    /// twice and a test asserting one role would pass anyway. That is the exact failure the server uses
    /// a single transaction to make impossible, so the client test asserts the same pair.
    /// </para>
    /// <para>
    /// It also goes through the armed confirmation rather than calling the command directly, since
    /// arming and confirming are where the target ids are carried — and carrying them on the selection
    /// instead is how a confirmation ends up applied to whatever was clicked last.
    /// </para>
    /// </remarks>
    [Fact]
    public async Task HandingOverAVault_MakesThemTheOwnerAndTheCallerAnAdmin()
    {
        await UnlockedAsync();

        var vaults = shell.Vaults;
        var colleague = server.AddAccount("bob@example.com", "Bob Example");

        await CreateVaultAsync(vaults, "Platform secrets");

        vaults.InviteEmail = "bob@example.com";
        await vaults.AddMemberCommand.ExecuteAsync(null);

        vaults.SelectedMember = vaults.Members.Single(member => member.UserId == colleague);

        vaults.HandOverCommand.Execute(null);

        vaults.IsConfirming.ShouldBeTrue("the hand-over has to be answered, not just pressed");
        vaults.ShowsVaultActions.ShouldBeFalse("the buttons that armed it are replaced, not left live");

        await vaults.ConfirmActionCommand.ExecuteAsync(null);

        vaults.Members.Single(member => member.UserId == colleague).Role.ShouldBe("OWNER");
        vaults.Members.Single(member => member.IsSelf).Role.ShouldBe("ADMIN");
        vaults.IsConfirming.ShouldBeFalse();
    }

    /// <remarks>
    /// Renaming reaches the rest of the shell, which is the half a client can get wrong quietly: the name
    /// is drawn on the badge of every host card in a session holding more than one vault, in the
    /// file-this-into picker, and in the tab strip's menu.
    /// </remarks>
    [Fact]
    public async Task RenamingAVault_ReachesTheKeychainScreensPickerToo()
    {
        await UnlockedAsync();

        var vaults = shell.Vaults;

        await CreateVaultAsync(vaults, "Platform secrets");

        var vaultId = vaults.SelectedVault!.VaultId;

        vaults.RenameVaultCommand.Execute(null);
        vaults.EditVaultName = "Platform";

        await vaults.SaveVaultNameCommand.ExecuteAsync(null);

        vaults.Vaults.Single(vault => vault.VaultId == vaultId).Name.ShouldBe("Platform");
        vaults.Status.ShouldContain("re-encrypted");

        await shell.Vault!.LoadAsync(Token);

        shell.Vault.TargetVaults
            .Single(choice => choice.VaultId == vaultId)
            .Name
            .ShouldBe("Platform");
    }

    /// <remarks>
    /// <para>
    /// The address the directory does not know used to be a dead end — the screen said they had to sign
    /// in first and stopped. It invites them instead, from the same button, because which of the two
    /// applies is a fact about the server's account table rather than about what the user is doing.
    /// </para>
    /// <para>
    /// The status assertion is the point of the test. Nothing is sent, and an interface that said
    /// "invited" without saying that would leave somebody waiting for an email that is never coming.
    /// </para>
    /// </remarks>
    [Fact]
    public async Task AddingAnAddressWithNoAccount_InvitesItAndSaysNothingWasSent()
    {
        await UnlockedAsync();

        var vaults = shell.Vaults;

        await CreateVaultAsync(vaults, "Platform secrets");

        vaults.InviteEmail = "newcomer@example.com";
        await vaults.AddMemberCommand.ExecuteAsync(null);

        vaults.Members.ShouldHaveSingleItem("nobody has joined — they have only been invited");

        var invitation = vaults.Invitations.ShouldHaveSingleItem();

        invitation.Email.ShouldBe("newcomer@example.com");
        invitation.IsPending.ShouldBeTrue();
        invitation.State.ShouldContain("Nothing was sent");

        vaults.Status.ShouldContain("cannot send mail");
    }

    /// <remarks>
    /// <para>
    /// The regression this whole path was rewritten for. An account exists from its owner's first
    /// authenticated request and publishes no key until they choose a passphrase on their own machine,
    /// and the directory omits it for that entire window — an entry exists to be wrapped to, and this
    /// one has nothing to wrap. Reading that silence as "there is no such account" meant ADD quietly
    /// issued an invitation instead: the members list did not change, the screen said they had no
    /// account here, and they only actually joined on the next hourly sweep.
    /// </para>
    /// <para>
    /// So the assertion is that they are a <em>member</em>, not an invitation, and that the row says
    /// what is true of them — no key, so nothing can be shared with them yet.
    /// </para>
    /// </remarks>
    [Fact]
    public async Task AddingAnAccountThatHasNotEnrolled_MakesThemAMemberWithNoKey()
    {
        await UnlockedAsync();

        var vaults = shell.Vaults;
        var colleague = server.AddUnenrolledAccount("carol@example.com", "Carol Example");

        await CreateVaultAsync(vaults, "Platform secrets");

        vaults.InviteEmail = "carol@example.com";
        await vaults.AddMemberCommand.ExecuteAsync(null);

        vaults.Invitations.ShouldBeEmpty("they have an account here, so there is nothing to invite");

        vaults.Members.Count.ShouldBe(2, vaults.Status);

        var member = vaults.Members.Single(row => row.UserId == colleague);

        member.Email.ShouldBe("carol@example.com");

        // The label the user asked to see, and the reason SHARE KEY is not the next step.
        member.KeyState.ShouldContain("no key yet");

        vaults.Status.ShouldContain("Added");
        vaults.Status.ShouldContain("no key yet");
    }

    /// <remarks>
    /// The other half of the pair above: an address with no account at all still falls through to an
    /// invitation. It is the server that decides which, so this proves the fall-through survived being
    /// moved behind it rather than being replaced by an error.
    /// </remarks>
    [Fact]
    public async Task AddingAnAddressWithNoAccount_StillInvitesRatherThanFailing()
    {
        await UnlockedAsync();

        var vaults = shell.Vaults;

        await CreateVaultAsync(vaults, "Platform secrets");

        vaults.InviteEmail = "stranger@example.com";
        await vaults.AddMemberCommand.ExecuteAsync(null);

        vaults.Members.ShouldHaveSingleItem("nobody has joined — they have only been invited");
        vaults.Invitations.ShouldHaveSingleItem().Email.ShouldBe("stranger@example.com");
    }

    /// <remarks>
    /// A withdrawn invitation stays on the list saying it was withdrawn, rather than vanishing. One that
    /// disappeared would read as never having been sent, which is the same thing the screen looks like
    /// before anybody does anything.
    /// </remarks>
    [Fact]
    public async Task WithdrawingAnInvitation_LeavesItListedAsWithdrawn()
    {
        await UnlockedAsync();

        var vaults = shell.Vaults;

        await CreateVaultAsync(vaults, "Platform secrets");

        vaults.InviteEmail = "newcomer@example.com";
        await vaults.AddMemberCommand.ExecuteAsync(null);

        vaults.SelectedInvitation = vaults.Invitations.ShouldHaveSingleItem();

        await vaults.RevokeInvitationCommand.ExecuteAsync(null);

        vaults.Invitations.ShouldHaveSingleItem().State.ShouldBe("withdrawn");
        vaults.Status.ShouldContain("Withdrew the invitation");
    }

    /// <remarks>
    /// <para>
    /// A reload rebuilds the vault list and reselects, so a reload that changed the selection — creating
    /// the first shared vault is exactly that — used to leave two reads of the same membership list in
    /// flight: the one the reload awaits, and one the selection handler started on its own. Both clear the
    /// member list and then both append to it, so every member was drawn twice. On a vault nobody has been
    /// added to yet, whose only member is its owner, that read as the owner being in it twice.
    /// </para>
    /// <para>
    /// Counted rather than inferred from the list, and the gate is why: against a fake that answers from
    /// memory each read finishes before the next begins, so the duplicate never appears and the bug
    /// survives the test. Holding the read open is what makes this behave like a server.
    /// </para>
    /// </remarks>
    [Fact]
    public async Task CreatingAVault_ReadsItsMembersOnce()
    {
        await UnlockedAsync();

        var vaults = shell.Vaults;

        await vaults.LoadAsync(Token);

        vaults.NewVaultCommand.Execute(null);
        vaults.NewVaultName = "Platform secrets";

        var gate = new TaskCompletionSource();

        server.MemberReadGate = gate;

        var create = vaults.CreateVaultCommand.ExecuteAsync(null);

        // Asserted while the read is still in flight: that is the only moment at which a second read
        // started by the selection handler is distinguishable from the reload's own.
        server.MemberReads.ShouldBe(1, "a reload reads the selected vault's members once");

        gate.SetResult();

        await create;

        vaults.Members.ShouldHaveSingleItem().Role.ShouldBe("OWNER");
    }

    /// <remarks>
    /// Through the form rather than straight at the command, because the name is what the form is for —
    /// and because the form is now the only way in: there is no separate "make a team" step behind it.
    /// </remarks>
    private static async Task CreateVaultAsync(VaultsViewModel vaults, string name)
    {
        await vaults.LoadAsync(Token);

        vaults.NewVaultCommand.Execute(null);
        vaults.NewVaultName = name;

        await vaults.CreateVaultCommand.ExecuteAsync(null);

        vaults.IsCreatingVault.ShouldBeFalse(vaults.Status);
        vaults.SelectedVault.ShouldNotBeNull(vaults.Status);
        vaults.SelectedVault!.IsShared.ShouldBeTrue(vaults.Status);
    }

    /// <remarks>
    /// The whole path rather than a shortcut into the unlocked state, because sharing needs an identity
    /// key that was really enrolled: the fake server publishes it into its key log during enrollment, and
    /// that entry is what the client verifies its own directory answer against.
    /// </remarks>
    private async Task UnlockedAsync()
    {
        await shell.StartAsync(Token);
        await shell.SignInCommand.ExecuteAsync(null);

        shell.Passphrase = Passphrase;
        shell.ConfirmPassphrase = Passphrase;
        await shell.EnrollCommand.ExecuteAsync(null);

        shell.RecoveryCodeWrittenDown = true;
        shell.ConfirmRecoveryCodeCommand.Execute(null);

        shell.Passphrase = Passphrase;
        await shell.UnlockCommand.ExecuteAsync(null);

        shell.State.ShouldBe(ShellState.Unlocked, shell.StatusMessage);
    }
}