DodoSSH/tests/DodoSSH.Client.App.Tests/TeamSharingTests.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>
/// Teams, from the side that holds the keys: create one, add somebody, and wrap a vault key to them.
/// </summary>
/// <remarks>
/// <para>
/// The reason this suite exists rather than leaving teams 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>
/// </remarks>
public sealed class TeamSharingTests : 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-teams-{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 team, in one test. Adding somebody wraps every team vault this machine can
    /// open to them, so the status line names what they were given rather than what is still owed —
    /// and the grant is on the server before the add has finished reporting.
    /// </remarks>
    [Fact]
    public async Task AddingAMember_WrapsEveryTeamVaultThisMachineHoldsToThem()
    {
        await UnlockedAsync();

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

        await CreateTeamAsync(teams, "Platform", "platform");

        await CreateVaultAsync(teams, "Platform secrets");
        teams.Vaults.Count.ShouldBe(1, teams.Status);

        var vaultId = teams.Vaults[0].VaultId;

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

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

        server.IssuedGrants.ShouldContainKey(
            (vaultId, colleague),
            "adding somebody to a team is what shares its vaults with them");

        teams.Status.ShouldContain("Platform secrets");
    }

    /// <remarks>
    /// <para>
    /// The other half of the same idea. Removing somebody withdraws their grants — which only blocks
    /// future reads — so the vault is rotated in the same breath and the new key goes to the people who
    /// are left. From that moment nothing written is readable to the person who went.
    /// </para>
    /// <para>
    /// The remaining member is given the earlier generation as well as the new one, which is what keeps
    /// the vault's existing items readable to them: a rotation re-keys the vault, not its contents.
    /// </para>
    /// </remarks>
    [Fact]
    public async Task RemovingAMember_RotatesTheVaultAndHandsTheNewKeyToWhoIsLeft()
    {
        await UnlockedAsync();

        var teams = shell.Teams;
        var leaving = server.AddAccount("bob@example.com", "Bob Example");
        var staying = server.AddAccount("carol@example.com", "Carol Example");

        await CreateTeamAsync(teams, "Platform", "platform");
        await CreateVaultAsync(teams, "Platform secrets");

        var vaultId = teams.Vaults[0].VaultId;

        foreach (var address in (string[])["bob@example.com", "carol@example.com"])
        {
            teams.InviteEmail = address;
            await teams.AddMemberCommand.ExecuteAsync(null);
        }

        teams.Members.Count.ShouldBe(3, teams.Status);

        teams.SelectedMember = teams.Members.Single(member => member.UserId == leaving);

        await teams.RemoveMemberCommand.ExecuteAsync(null);

        teams.Status.ShouldContain("Rotated", customMessage: teams.Status);
        teams.Status.ShouldContain("Platform secrets");

        // The last act of a rotation is moving what is already stored onto the new key. Proven by the
        // bytes in DodoSSH.Client.Sync.Tests; what this asserts is that the shell asks for it at all,
        // and says which of the two guarantees the user has ended up with.
        teams.Status.ShouldContain("re-sealed under the new key", customMessage: teams.Status);

        // Gone entirely, at every generation. A revocation that left the history behind would leave them
        // able to read everything written before they went, from a copy of the ciphertext.
        server.GenerationsGranted(vaultId, leaving).ShouldBeEmpty();

        // And the member who stayed holds both: the new key for what comes next, the old one for what
        // is already stored under it.
        server.GenerationsGranted(vaultId, staying).ShouldBe([1u, 2u]);
    }

    /// <remarks>
    /// Somebody added after a rotation is given every generation the sharing machine holds, not only the
    /// newest. A vault shared as one key would open to a list of items that will not decrypt, which
    /// reads as corruption rather than as the missing grant it is.
    /// </remarks>
    [Fact]
    public async Task AddingAMemberToARotatedVault_HandsThemItsHistoryAsWell()
    {
        await UnlockedAsync();

        var teams = shell.Teams;
        var first = server.AddAccount("bob@example.com", "Bob Example");
        var second = server.AddAccount("carol@example.com", "Carol Example");

        await CreateTeamAsync(teams, "Platform", "platform");
        await CreateVaultAsync(teams, "Platform secrets");

        var vaultId = teams.Vaults[0].VaultId;

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

        // Removing them is what rotates the vault, so the next person to be added arrives at a vault
        // with a history rather than one that has only ever had a single key.
        teams.SelectedMember = teams.Members.Single(member => member.UserId == first);
        await teams.RemoveMemberCommand.ExecuteAsync(null);

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

        server.GenerationsGranted(vaultId, second).ShouldBe([1u, 2u], teams.Status);
    }

    /// <remarks>
    /// The manual path still works and is still worth having: a vault whose key this machine did not
    /// hold when somebody was added is shared by pressing the button once it does. Re-wrapping to
    /// somebody who already holds the key is the same call, and the server replaces the row rather than
    /// adding a second one.
    /// </remarks>
    [Fact]
    public async Task SharingAVaultByHand_WrapsTheKeyAndSaysWhatItCannotPromise()
    {
        await UnlockedAsync();

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

        await CreateTeamAsync(teams, "Platform", "platform");
        await CreateVaultAsync(teams, "Platform secrets");

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

        teams.SelectedMember = teams.Members.Single(member => member.UserId == colleague);
        teams.SelectedVault = teams.Vaults[0];

        await teams.ShareVaultCommand.ExecuteAsync(null);

        var vaultId = teams.Vaults[0].VaultId;

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

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

    /// <remarks>
    /// <para>
    /// The test this whole design exists for. A server that wants to read a team's 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 teams = shell.Teams;
        var colleague = server.AddAccount("mallory@example.com", "Mallory Example");

        await CreateTeamAsync(teams, "Platform", "platform");
        await CreateVaultAsync(teams, "Platform secrets");

        // Before the add, because the add now shares. Both routes to a wrap have to refuse, and a test
        // that corrupted the log afterwards would be asserting about the second one only.
        server.CorruptKeyLog = true;

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

        var vaultId = teams.Vaults[0].VaultId;

        server.IssuedGrants.ShouldNotContainKey((vaultId, colleague));
        teams.Status.ShouldContain("Could not share");
        teams.Status.ShouldContain("key log");

        teams.SelectedMember = teams.Members.Single(member => member.UserId == colleague);
        teams.SelectedVault = teams.Vaults[0];

        await teams.ShareVaultCommand.ExecuteAsync(null);

        server.IssuedGrants.ShouldNotContainKey((vaultId, colleague));
        teams.Status.ShouldContain("Did not share");
        teams.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 ATeamVaultCreatedHere_IsImmediatelyReadableAndWritable()
    {
        await UnlockedAsync();

        var teams = shell.Teams;

        await CreateTeamAsync(teams, "Platform", "platform");
        await CreateVaultAsync(teams, "Platform secrets");

        var vaultId = teams.Vaults[0].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>
    /// Filing into a team 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 AHostFiledIntoATeamVault_StaysThere()
    {
        await UnlockedAsync();

        var teams = shell.Teams;

        await CreateTeamAsync(teams, "Platform", "platform");
        await CreateVaultAsync(teams, "Platform secrets");

        var vault = shell.Vault!;
        var teamVaultId = teams.Vaults[0].VaultId;

        await vault.LoadAsync(Token);

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

        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 team's vault.
        vault.SelectedTargetVault =
            vault.TargetVaults.First(choice => choice.VaultId != teamVaultId);

        await vault.SaveHostCommand.ExecuteAsync(null);

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

    /// <remarks>
    /// The mirror image of the host test above, and it goes the other way on purpose. A host filed into a
    /// team 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 teams = shell.Teams;

        await CreateTeamAsync(teams, "Platform", "platform");
        await CreateVaultAsync(teams, "Platform secrets");

        var teamVaultId = teams.Vaults[0].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 == teamVaultId);

        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", which until now it could not give at all —
    /// the endpoint existed and nothing called it. Asserted after a share rather than before, because
    /// an empty list proves nothing about whether the call was made.
    /// </remarks>
    [Fact]
    public async Task SelectingATeamVault_ListsWhoHoldsAKeyToIt()
    {
        await UnlockedAsync();

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

        await CreateTeamAsync(teams, "Platform", "platform");
        await CreateVaultAsync(teams, "Platform secrets");

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

        teams.SelectedMember = teams.Members.Single(member => member.UserId == colleague);
        teams.SelectedVault = teams.Vaults[0];

        await teams.ShareVaultCommand.ExecuteAsync(null);

        // Selecting the vault again is what drives the read; the share above happened after the
        // previous selection had already loaded an empty list.
        teams.SelectedVault = null;
        teams.SelectedVault = teams.Vaults[0];

        // Two, and the second one matters: the creator's own grant is recorded when the vault is made,
        // so a list that showed only the people it was shared with would be describing a vault its
        // owner cannot open.
        teams.Grants.Count.ShouldBe(2, teams.Status);

        var holder = teams.Grants.Single(row => row.UserId == colleague);

        holder.IsLive.ShouldBeTrue(teams.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 teams = shell.Teams;
        var colleague = server.AddAccount("bob@example.com", "Bob Example");

        await CreateTeamAsync(teams, "Platform", "platform");

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

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

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

        teams.Members.Single(member => member.UserId == colleague).Role.ShouldBe("ADMIN");
        teams.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 teams = shell.Teams;
        var colleague = server.AddAccount("bob@example.com", "Bob Example");

        await CreateTeamAsync(teams, "Platform", "platform");

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

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

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

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

    /// <remarks>
    /// <para>
    /// Both halves, because a transfer that only promoted the recipient would leave the team 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 id is carried — and carrying it on the selection
    /// instead is how a confirmation ends up applied to whatever was clicked last.
    /// </para>
    /// </remarks>
    [Fact]
    public async Task HandingOverATeam_MakesThemTheOwnerAndTheCallerAnAdmin()
    {
        await UnlockedAsync();

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

        await CreateTeamAsync(teams, "Platform", "platform");

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

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

        teams.TransferOwnershipCommand.Execute(null);

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

        await teams.ConfirmActionCommand.ExecuteAsync(null);

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

    /// <remarks>
    /// Archiving is refused while the team owns a vault, and the refusal has to reach the screen. The
    /// failure this guards is the quiet one: a client that swallowed the 409 and reloaded would show a
    /// team that is still there with no explanation of why nothing happened.
    /// </remarks>
    [Fact]
    public async Task ArchivingATeamThatOwnsAVault_IsRefusedAndSaysWhy()
    {
        await UnlockedAsync();

        var teams = shell.Teams;

        await CreateTeamAsync(teams, "Platform", "platform");
        await CreateVaultAsync(teams, "Platform secrets");

        teams.ArchiveTeamCommand.Execute(null);
        await teams.ConfirmActionCommand.ExecuteAsync(null);

        teams.Teams.ShouldContain(team => team.Slug == "platform");
        teams.Status.ShouldContain("holding a key");
    }

    /// <remarks>
    /// An empty team can go, and this is the only operation on the screen that removes something from
    /// everybody's list at once.
    /// </remarks>
    [Fact]
    public async Task ArchivingAnEmptyTeam_RemovesIt()
    {
        await UnlockedAsync();

        var teams = shell.Teams;

        await CreateTeamAsync(teams, "Platform", "platform");

        teams.ArchiveTeamCommand.Execute(null);
        await teams.ConfirmActionCommand.ExecuteAsync(null);

        teams.Teams.ShouldNotContain(team => team.Slug == "platform");
        teams.Status.ShouldContain("Archived");
    }

    /// <remarks>
    /// Renaming leaves the slug alone, and the status line says so unprompted — somebody who assumed
    /// otherwise would find out from a URL much later, which is the worst moment to find out.
    /// </remarks>
    [Fact]
    public async Task RenamingATeam_LeavesItsSlugAlone()
    {
        await UnlockedAsync();

        var teams = shell.Teams;

        await CreateTeamAsync(teams, "Platform", "platform");

        teams.RenameTeamCommand.Execute(null);
        teams.EditTeamName = "Platform Engineering";

        await teams.SaveTeamCommand.ExecuteAsync(null);

        var team = teams.Teams.ShouldHaveSingleItem();

        team.Name.ShouldBe("Platform Engineering");
        team.Slug.ShouldBe("platform");
        teams.Status.ShouldContain("slug is still '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 teams = shell.Teams;

        await CreateTeamAsync(teams, "Platform", "platform");

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

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

        var invitation = teams.Invitations.ShouldHaveSingleItem();

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

        teams.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 MEMBER
    /// 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 teams = shell.Teams;
        var colleague = server.AddUnenrolledAccount("carol@example.com", "Carol Example");

        await CreateTeamAsync(teams, "Platform", "platform");

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

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

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

        var member = teams.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");

        teams.Status.ShouldContain("Added");
        teams.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 teams = shell.Teams;

        await CreateTeamAsync(teams, "Platform", "platform");

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

        teams.Members.ShouldHaveSingleItem("nobody has joined — they have only been invited");
        teams.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 teams = shell.Teams;

        await CreateTeamAsync(teams, "Platform", "platform");

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

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

        await teams.RevokeInvitationCommand.ExecuteAsync(null);

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

    /// <remarks>
    /// <para>
    /// A reload rebuilds the team list and reselects, so a reload that changed the selection — creating
    /// the first team is exactly that — used to leave two reads of the same team 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 team nobody has been added to yet,
    /// whose only member is its owner, that read as the owner being in the team 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 CreatingATeam_ReadsItsMembersOnce()
    {
        await UnlockedAsync();

        var teams = shell.Teams;

        await teams.LoadAsync(Token);

        teams.NewTeamCommand.Execute(null);
        teams.NewTeamName = "Platform";
        teams.NewTeamSlug = "platform";

        var gate = new TaskCompletionSource();

        server.MemberReadGate = gate;

        var create = teams.CreateTeamCommand.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 team's members once");

        gate.SetResult();

        await create;

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

    /// <remarks>
    /// Through the form rather than straight at the command, because the name is what the form is for: a
    /// vault used to be named after its team, which gave a team with three of them three vaults called the
    /// same thing.
    /// </remarks>
    private async Task CreateVaultAsync(TeamsViewModel teams, string name)
    {
        teams.NewVaultCommand.Execute(null);
        teams.NewVaultName = name;

        await teams.CreateVaultCommand.ExecuteAsync(null);

        teams.IsCreatingVault.ShouldBeFalse(teams.Status);
    }

    private async Task CreateTeamAsync(TeamsViewModel teams, string name, string slug)
    {
        await teams.LoadAsync(Token);

        teams.NewTeamCommand.Execute(null);
        teams.NewTeamName = name;
        teams.NewTeamSlug = slug;

        await teams.CreateTeamCommand.ExecuteAsync(null);

        teams.SelectedTeam.ShouldNotBeNull(teams.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);
    }
}