diff --git a/.gitignore b/.gitignore
index c5c4672b..aa39b719 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,3 +2,4 @@
 !.gitignore
 !/.cargo
 /target
+/testruns
diff --git a/Cargo.toml b/Cargo.toml
index dcff4f90..5d14ca93 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -54,3 +54,4 @@ opt-level = 3
 
 [features]
 rc_tracking = []
+it = []
diff --git a/src/acceptor.rs b/src/acceptor.rs
index 7cb619a8..02401f6a 100644
--- a/src/acceptor.rs
+++ b/src/acceptor.rs
@@ -7,7 +7,7 @@ use {
     },
     std::rc::Rc,
     thiserror::Error,
-    uapi::{c, format_ustr, Errno, OwnedFd, Ustring},
+    uapi::{c, format_ustr, Errno, OwnedFd, Ustr, Ustring},
 };
 
 #[derive(Debug, Error)]
@@ -48,7 +48,7 @@ pub struct Acceptor {
 
 struct AllocatedSocket {
     // wayland-x
-    name: Ustring,
+    name: String,
     // /run/user/1000/wayland-x
     path: Ustring,
     insecure: Rc<OwnedFd>,
@@ -56,6 +56,8 @@ struct AllocatedSocket {
     lock_path: Ustring,
     _lock_fd: OwnedFd,
     // /run/user/1000/wayland-x.jay
+    #[cfg_attr(not(feature = "it"), allow(dead_code))]
+    secure_path: Ustring,
     secure: Rc<OwnedFd>,
 }
 
@@ -74,8 +76,8 @@ fn bind_socket(
 ) -> Result<AllocatedSocket, AcceptorError> {
     let mut addr: c::sockaddr_un = uapi::pod_zeroed();
     addr.sun_family = c::AF_UNIX as _;
-    let name = format_ustr!("wayland-{}", id);
-    let path = format_ustr!("{}/{}", xrd, name.display());
+    let name = format!("wayland-{}", id);
+    let path = format_ustr!("{}/{}", xrd, name);
     let jay_path = format_ustr!("{}.jay", path.display());
     let lock_path = format_ustr!("{}.lock", path.display());
     if jay_path.len() + 1 > addr.sun_path.len() {
@@ -110,6 +112,7 @@ fn bind_socket(
         insecure: insecure.clone(),
         lock_path,
         _lock_fd: lock_fd,
+        secure_path: jay_path,
         secure: secure.clone(),
     })
 }
@@ -145,7 +148,7 @@ fn allocate_socket() -> Result<AllocatedSocket, AcceptorError> {
 }
 
 impl Acceptor {
-    pub fn install(state: &Rc<State>) -> Result<Rc<String>, AcceptorError> {
+    pub fn install(state: &Rc<State>) -> Result<Rc<Acceptor>, AcceptorError> {
         let socket = allocate_socket()?;
         log::info!("bound to socket {}", socket.path.display());
         for fd in [&socket.secure, &socket.insecure] {
@@ -155,7 +158,6 @@ impl Acceptor {
         }
         let id1 = state.el.id();
         let id2 = state.el.id();
-        let name = socket.name.to_owned();
         let acc = Rc::new(Acceptor {
             ids: [id1, id2],
             socket,
@@ -169,10 +171,18 @@ impl Acceptor {
         )?;
         state
             .el
-            .insert(id2, Some(acc.socket.secure.raw()), c::EPOLLIN, acc)?;
-        let name = Rc::new(name.display().to_string());
-        state.socket_path.set(name.clone());
-        Ok(name)
+            .insert(id2, Some(acc.socket.secure.raw()), c::EPOLLIN, acc.clone())?;
+        state.acceptor.set(Some(acc.clone()));
+        Ok(acc)
+    }
+
+    pub fn socket_name(&self) -> &str {
+        &self.socket.name
+    }
+
+    #[cfg_attr(not(feature = "it"), allow(dead_code))]
+    pub fn secure_path(&self) -> &Ustr {
+        self.socket.secure_path.as_ustr()
     }
 }
 
diff --git a/src/backend.rs b/src/backend.rs
index c21de5e5..0c877e0f 100644
--- a/src/backend.rs
+++ b/src/backend.rs
@@ -6,6 +6,7 @@ use {
         video::drm::ConnectorType,
     },
     std::{
+        any::Any,
         error::Error,
         fmt::{Debug, Display, Formatter},
         rc::Rc,
@@ -17,6 +18,7 @@ linear_ids!(InputDeviceIds, InputDeviceId);
 
 pub trait Backend {
     fn run(self: Rc<Self>) -> SpawnedFuture<Result<(), Box<dyn Error>>>;
+    fn into_any(self: Rc<Self>) -> Rc<dyn Any>;
 
     fn switch_to(&self, vtnr: u32) {
         let _ = vtnr;
@@ -30,7 +32,7 @@ pub trait Backend {
         false
     }
 
-    fn is_freestanding(&self) -> bool {
+    fn import_environment(&self) -> bool {
         false
     }
 
@@ -57,6 +59,7 @@ pub struct MonitorInfo {
     pub height_mm: i32,
 }
 
+#[derive(Copy, Clone, Debug)]
 pub struct ConnectorKernelId {
     pub ty: ConnectorType,
     pub idx: u32,
@@ -84,6 +87,8 @@ pub enum ConnectorEvent {
     ModeChanged(Mode),
 }
 
+pub type TransformMatrix = [[f64; 2]; 2];
+
 pub trait InputDevice {
     fn id(&self) -> InputDeviceId;
     fn removed(&self) -> bool;
@@ -94,11 +99,11 @@ pub trait InputDevice {
     fn set_left_handed(&self, left_handed: bool);
     fn set_accel_profile(&self, profile: InputDeviceAccelProfile);
     fn set_accel_speed(&self, speed: f64);
-    fn set_transform_matrix(&self, matrix: [[f64; 2]; 2]);
+    fn set_transform_matrix(&self, matrix: TransformMatrix);
     fn name(&self) -> Rc<String>;
 }
 
-#[derive(Debug, Copy, Clone)]
+#[derive(Debug, Copy, Clone, Hash, Eq, PartialEq)]
 pub enum InputDeviceCapability {
     Keyboard,
     Pointer,
diff --git a/src/backends/dummy.rs b/src/backends/dummy.rs
index c8b372c4..4473c060 100644
--- a/src/backends/dummy.rs
+++ b/src/backends/dummy.rs
@@ -4,7 +4,7 @@ use {
         backend::{Backend, Connector, ConnectorEvent, ConnectorId, ConnectorKernelId},
         video::drm::ConnectorType,
     },
-    std::{error::Error, rc::Rc},
+    std::{any::Any, error::Error, rc::Rc},
 };
 
 pub struct DummyBackend;
@@ -13,6 +13,10 @@ impl Backend for DummyBackend {
     fn run(self: Rc<Self>) -> SpawnedFuture<Result<(), Box<dyn Error>>> {
         unreachable!();
     }
+
+    fn into_any(self: Rc<Self>) -> Rc<dyn Any> {
+        self
+    }
 }
 
 pub struct DummyOutput {
diff --git a/src/backends/metal.rs b/src/backends/metal.rs
index 448b31fa..33012c6f 100644
--- a/src/backends/metal.rs
+++ b/src/backends/metal.rs
@@ -7,7 +7,7 @@ use {
         async_engine::{AsyncError, AsyncFd, SpawnedFuture},
         backend::{
             Backend, BackendEvent, InputDevice, InputDeviceAccelProfile, InputDeviceCapability,
-            InputDeviceId, InputEvent, KeyState,
+            InputDeviceId, InputEvent, KeyState, TransformMatrix,
         },
         backends::metal::video::{MetalDrmDevice, PendingDrmDevice},
         dbus::{DbusError, SignalHandler},
@@ -40,6 +40,7 @@ use {
         },
     },
     std::{
+        any::Any,
         cell::{Cell, RefCell},
         error::Error,
         ffi::{CStr, CString},
@@ -148,6 +149,10 @@ impl Backend for MetalBackend {
         })
     }
 
+    fn into_any(self: Rc<Self>) -> Rc<dyn Any> {
+        self
+    }
+
     fn switch_to(&self, vtnr: u32) {
         self.session.switch_to(vtnr, move |res| {
             if let Err(e) = res {
@@ -188,7 +193,7 @@ impl Backend for MetalBackend {
         true
     }
 
-    fn is_freestanding(&self) -> bool {
+    fn import_environment(&self) -> bool {
         true
     }
 
@@ -288,7 +293,7 @@ struct MetalInputDevice {
     left_handed: Cell<Option<bool>>,
     accel_profile: Cell<Option<AccelProfile>>,
     accel_speed: Cell<Option<f64>>,
-    transform_matrix: Cell<Option<[[f64; 2]; 2]>>,
+    transform_matrix: Cell<Option<TransformMatrix>>,
 }
 
 impl Drop for MetalInputDevice {
@@ -419,7 +424,7 @@ impl InputDevice for MetalInputDevice {
         }
     }
 
-    fn set_transform_matrix(&self, matrix: [[f64; 2]; 2]) {
+    fn set_transform_matrix(&self, matrix: TransformMatrix) {
         self.transform_matrix.set(Some(matrix));
     }
 
diff --git a/src/backends/x.rs b/src/backends/x.rs
index 3a965f45..f7655d5c 100644
--- a/src/backends/x.rs
+++ b/src/backends/x.rs
@@ -4,7 +4,7 @@ use {
         backend::{
             AxisSource, Backend, BackendEvent, Connector, ConnectorEvent, ConnectorId,
             ConnectorKernelId, InputDevice, InputDeviceAccelProfile, InputDeviceCapability,
-            InputDeviceId, InputEvent, KeyState, Mode, MonitorInfo, ScrollAxis,
+            InputDeviceId, InputEvent, KeyState, Mode, MonitorInfo, ScrollAxis, TransformMatrix,
         },
         fixed::Fixed,
         format::XRGB8888,
@@ -48,6 +48,7 @@ use {
         },
     },
     std::{
+        any::Any,
         borrow::Cow,
         cell::{Cell, RefCell},
         collections::VecDeque,
@@ -242,6 +243,10 @@ impl Backend for XBackend {
             Ok(())
         })
     }
+
+    fn into_any(self: Rc<Self>) -> Rc<dyn Any> {
+        self
+    }
 }
 
 pub struct XBackend {
@@ -1054,7 +1059,7 @@ impl InputDevice for XSeatKeyboard {
         let _ = speed;
     }
 
-    fn set_transform_matrix(&self, matrix: [[f64; 2]; 2]) {
+    fn set_transform_matrix(&self, matrix: TransformMatrix) {
         let _ = matrix;
     }
 
@@ -1103,7 +1108,7 @@ impl InputDevice for XSeatMouse {
         let _ = speed;
     }
 
-    fn set_transform_matrix(&self, matrix: [[f64; 2]; 2]) {
+    fn set_transform_matrix(&self, matrix: TransformMatrix) {
         let _ = matrix;
     }
 
diff --git a/src/cli.rs b/src/cli.rs
index 130b8358..b75582ab 100644
--- a/src/cli.rs
+++ b/src/cli.rs
@@ -44,6 +44,8 @@ pub enum Cmd {
     Screenshot(ScreenshotArgs),
     /// Inspect/modify the idle (screensaver) settings.
     Idle(IdleArgs),
+    #[cfg(feature = "it")]
+    RunTests,
 }
 
 #[derive(Args, Debug)]
@@ -101,7 +103,7 @@ pub struct ScreenshotArgs {
     pub filename: Option<String>,
 }
 
-#[derive(Args, Debug)]
+#[derive(Args, Debug, Default)]
 pub struct RunArgs {
     /// The backends to try.
     ///
@@ -184,5 +186,7 @@ pub fn main() {
         Cmd::SetLogLevel(a) => set_log_level::main(cli.global, a),
         Cmd::Screenshot(a) => screenshot::main(cli.global, a),
         Cmd::Idle(a) => idle::main(cli.global, a),
+        #[cfg(feature = "it")]
+        Cmd::RunTests => crate::it::run_tests(),
     }
 }
diff --git a/src/client.rs b/src/client.rs
index 1584efc8..a91e35cc 100644
--- a/src/client.rs
+++ b/src/client.rs
@@ -42,6 +42,11 @@ impl ClientId {
     pub fn raw(self) -> u64 {
         self.0
     }
+
+    #[cfg_attr(not(feature = "it"), allow(dead_code))]
+    pub fn from_raw(val: u64) -> Self {
+        Self(val)
+    }
 }
 
 impl Display for ClientId {
diff --git a/src/compositor.rs b/src/compositor.rs
index aabfbdb9..6a7116aa 100644
--- a/src/compositor.rs
+++ b/src/compositor.rs
@@ -1,3 +1,5 @@
+#[cfg(feature = "it")]
+use crate::it::test_backend::TestBackend;
 use {
     crate::{
         acceptor::{Acceptor, AcceptorError},
@@ -36,7 +38,7 @@ use {
     },
     ahash::AHashSet,
     forker::ForkerProxy,
-    std::{cell::Cell, ops::Deref, rc::Rc, sync::Arc, time::Duration},
+    std::{cell::Cell, future::Future, ops::Deref, rc::Rc, sync::Arc, time::Duration},
     thiserror::Error,
     uapi::c,
 };
@@ -44,12 +46,9 @@ use {
 pub const MAX_EXTENTS: i32 = (1 << 22) - 1;
 
 pub fn start_compositor(global: GlobalArgs, args: RunArgs) {
-    let forker = match ForkerProxy::create() {
-        Ok(f) => Rc::new(f),
-        Err(e) => fatal!("Could not create a forker process: {}", ErrorFmt(e)),
-    };
+    let forker = create_forker();
     let logger = Logger::install_compositor(global.log_level.into());
-    if let Err(e) = start_compositor2(forker, logger.clone(), args) {
+    if let Err(e) = start_compositor2(forker, Some(logger.clone()), args, None) {
         let e = ErrorFmt(e);
         log::error!("A fatal error occurred: {}", e);
         eprintln!("A fatal error occurred: {}", e);
@@ -59,8 +58,21 @@ pub fn start_compositor(global: GlobalArgs, args: RunArgs) {
     log::info!("Exit");
 }
 
+#[cfg(feature = "it")]
+pub fn start_compositor_for_test(future: TestFuture) -> Result<(), CompositorError> {
+    let forker = create_forker();
+    start_compositor2(forker, None, RunArgs::default(), Some(future))
+}
+
+fn create_forker() -> Rc<ForkerProxy> {
+    match ForkerProxy::create() {
+        Ok(f) => Rc::new(f),
+        Err(e) => fatal!("Could not create a forker process: {}", ErrorFmt(e)),
+    }
+}
+
 #[derive(Debug, Error)]
-enum MainError {
+pub enum CompositorError {
     #[error("The client acceptor caused an error")]
     AcceptorError(#[from] AcceptorError),
     #[error("The event loop caused an error")]
@@ -86,11 +98,14 @@ const STATIC_VARS: &[(&str, &str)] = &[
     ("_JAVA_AWT_WM_NONREPARENTING", "1"),
 ];
 
+pub type TestFuture = Box<dyn Fn(&Rc<State>) -> Box<dyn Future<Output = ()>>>;
+
 fn start_compositor2(
     forker: Rc<ForkerProxy>,
-    logger: Arc<Logger>,
+    logger: Option<Arc<Logger>>,
     run_args: RunArgs,
-) -> Result<(), MainError> {
+    test_future: Option<TestFuture>,
+) -> Result<(), CompositorError> {
     log::info!("pid = {}", uapi::getpid());
     init_fd_limit();
     leaks::init();
@@ -155,19 +170,22 @@ fn start_compositor2(
             handler: Default::default(),
             queue: Default::default(),
         },
-        socket_path: Default::default(),
+        acceptor: Default::default(),
         serial: Default::default(),
         idle_inhibitor_ids: Default::default(),
         run_toplevel,
     });
     create_dummy_output(&state);
-    let socket_path = Acceptor::install(&state)?;
+    let acceptor = Acceptor::install(&state)?;
     forker.install(&state);
-    forker.setenv(WAYLAND_DISPLAY.as_bytes(), socket_path.as_bytes());
+    forker.setenv(
+        WAYLAND_DISPLAY.as_bytes(),
+        acceptor.socket_name().as_bytes(),
+    );
     for (key, val) in STATIC_VARS {
         forker.setenv(key.as_bytes(), val.as_bytes());
     }
-    let _compositor = engine.spawn(start_compositor3(state.clone()));
+    let _compositor = engine.spawn(start_compositor3(state.clone(), test_future));
     el.run()?;
     state.xwayland.handler.borrow_mut().take();
     state.clients.clear();
@@ -178,8 +196,8 @@ fn start_compositor2(
     Ok(())
 }
 
-async fn start_compositor3(state: Rc<State>) {
-    let backend = match create_backend(&state).await {
+async fn start_compositor3(state: Rc<State>, test_future: Option<TestFuture>) {
+    let backend = match create_backend(&state, test_future).await {
         Some(b) => b,
         _ => {
             log::error!("Could not create a backend");
@@ -190,8 +208,10 @@ async fn start_compositor3(state: Rc<State>) {
     state.backend.set(backend.clone());
     state.globals.add_singletons(&backend);
 
-    if backend.is_freestanding() {
-        import_environment(&state, WAYLAND_DISPLAY, &state.socket_path.get());
+    if backend.import_environment() {
+        if let Some(acc) = state.acceptor.get() {
+            import_environment(&state, WAYLAND_DISPLAY, acc.socket_name());
+        }
         for (key, val) in STATIC_VARS {
             import_environment(&state, key, val);
         }
@@ -228,7 +248,17 @@ fn start_global_event_handlers(
     res
 }
 
-async fn create_backend(state: &Rc<State>) -> Option<Rc<dyn Backend>> {
+async fn create_backend(
+    state: &Rc<State>,
+    #[allow(unused_variables)] test_future: Option<TestFuture>,
+) -> Option<Rc<dyn Backend>> {
+    #[cfg(feature = "it")]
+    if let Some(tf) = test_future {
+        return Some(Rc::new(TestBackend {
+            state: state.clone(),
+            test_future: tf,
+        }));
+    }
     let mut backends = &state.run_args.backends[..];
     if backends.is_empty() {
         backends = &[CliBackend::X11, CliBackend::Metal];
diff --git a/src/ifs/jay_compositor.rs b/src/ifs/jay_compositor.rs
index 3640a5b5..90085583 100644
--- a/src/ifs/jay_compositor.rs
+++ b/src/ifs/jay_compositor.rs
@@ -13,6 +13,7 @@ use {
         },
         wire::{jay_compositor::*, JayCompositorId},
     },
+    bstr::ByteSlice,
     log::Level,
     std::{ops::Deref, rc::Rc},
     thiserror::Error,
@@ -80,7 +81,11 @@ impl JayCompositor {
         let log_file = Rc::new(JayLogFile::new(req.id, &self.client));
         track!(self.client, log_file);
         self.client.add_client_obj(&log_file)?;
-        log_file.send_path(self.client.state.logger.path());
+        let path = match &self.client.state.logger {
+            Some(logger) => logger.path(),
+            _ => "".as_bytes().as_bstr(),
+        };
+        log_file.send_path(path);
         Ok(())
     }
 
@@ -106,7 +111,9 @@ impl JayCompositor {
             TRACE => Level::Trace,
             _ => return Err(JayCompositorError::UnknownLogLevel(req.level)),
         };
-        self.client.state.logger.set_level(level);
+        if let Some(logger) = &self.client.state.logger {
+            logger.set_level(level);
+        }
         Ok(())
     }
 
@@ -152,6 +159,15 @@ impl JayCompositor {
         self.client.add_client_obj(&idle)?;
         Ok(())
     }
+
+    fn get_client_id(&self, parser: MsgParser<'_, '_>) -> Result<(), JayCompositorError> {
+        let _req: GetClientId = self.client.parse(self, parser)?;
+        self.client.event(ClientId {
+            self_id: self.id,
+            client_id: self.client.id.raw(),
+        });
+        Ok(())
+    }
 }
 
 object_base! {
@@ -163,11 +179,12 @@ object_base! {
     SET_LOG_LEVEL => set_log_level,
     TAKE_SCREENSHOT => take_screenshot,
     GET_IDLE => get_idle,
+    GET_CLIENT_ID => get_client_id,
 }
 
 impl Object for JayCompositor {
     fn num_requests(&self) -> u32 {
-        GET_IDLE + 1
+        GET_CLIENT_ID + 1
     }
 }
 
diff --git a/src/it.rs b/src/it.rs
new file mode 100644
index 00000000..d055a3e3
--- /dev/null
+++ b/src/it.rs
@@ -0,0 +1,113 @@
+#![cfg(feature = "it")]
+
+use {
+    crate::it::{test_backend::TestBackend, testrun::TestRun, tests::TestCase},
+    ahash::AHashMap,
+    isnt::std_1::collections::IsntHashMapExt,
+    log::Level,
+    std::{
+        cell::{Cell, RefCell},
+        future::pending,
+        pin::Pin,
+        rc::Rc,
+        time::SystemTime,
+    },
+    uapi::c,
+};
+
+#[macro_use]
+mod test_error;
+#[macro_use]
+mod test_object;
+pub mod test_backend;
+mod test_client;
+mod test_ifs;
+mod test_logger;
+mod test_mem;
+mod test_transport;
+mod testrun;
+mod tests;
+
+pub fn run_tests() {
+    test_logger::install();
+    test_logger::set_level(Level::Trace);
+    let it_run = ItRun {
+        path: format!(
+            "{}/testruns/{}",
+            env!("CARGO_MANIFEST_DIR"),
+            humantime::format_rfc3339_millis(SystemTime::now())
+        ),
+        failed: Default::default(),
+    };
+    for test in tests::tests() {
+        run_test(&it_run, test);
+    }
+    let failed = it_run.failed.borrow_mut();
+    if failed.is_not_empty() {
+        let mut failed: Vec<_> = failed.iter().collect();
+        failed.sort_by_key(|f| f.0);
+        log::error!("The following tests failed:");
+        for (name, errors) in failed {
+            log::error!("    {}:", name);
+            for error in errors {
+                log::error!("        {}", error);
+            }
+        }
+        fatal!("Some tests failed");
+    }
+}
+
+struct ItRun {
+    path: String,
+    failed: RefCell<AHashMap<&'static str, Vec<String>>>,
+}
+
+fn run_test(it_run: &ItRun, test: &'static dyn TestCase) {
+    let dir = format!("{}/{}", it_run.path, test.name());
+    std::fs::create_dir_all(&dir).unwrap();
+    let log_path = format!("{}/log", dir);
+    let log_file = Rc::new(uapi::open(log_path.as_str(), c::O_WRONLY | c::O_CREAT, 0o644).unwrap());
+    test_logger::set_file(log_file);
+    let errors = Rc::new(Cell::new(Vec::new()));
+    let errors2 = errors.clone();
+    let res = crate::compositor::start_compositor_for_test(Box::new(move |state| {
+        let state = state.clone();
+        let server_addr = {
+            let mut addr: c::sockaddr_un = uapi::pod_zeroed();
+            addr.sun_family = c::AF_UNIX as _;
+            let acceptor = state.acceptor.get().unwrap();
+            let path = acceptor.secure_path();
+            let sun_path = uapi::as_bytes_mut(&mut addr.sun_path[..]);
+            sun_path[..path.len()].copy_from_slice(path.as_bytes());
+            sun_path[path.len()] = 0;
+            addr
+        };
+        let backend: Rc<TestBackend> = state.backend.get().into_any().downcast().unwrap();
+        let testrun = Rc::new(TestRun {
+            state: state.clone(),
+            backend,
+            errors: Default::default(),
+            server_addr,
+        });
+        let errors = errors2.clone();
+        Box::new(async move {
+            let future: Pin<_> = test.run(testrun.clone()).into();
+            if let Err(e) = future.await {
+                testrun.errors.push(e.to_string());
+            }
+            errors.set(testrun.errors.take());
+            state.el.stop();
+            pending().await
+        })
+    }));
+    let errors = errors.take();
+    if errors.len() > 0 {
+        log::error!("The following errors occurred:");
+        for e in &errors {
+            log::error!("    {}", e);
+        }
+        it_run.failed.borrow_mut().insert(test.name(), errors);
+    }
+    test_logger::unset_file();
+    let _ = res;
+}
diff --git a/src/it/test_backend.rs b/src/it/test_backend.rs
new file mode 100644
index 00000000..2b0fe542
--- /dev/null
+++ b/src/it/test_backend.rs
@@ -0,0 +1,136 @@
+use {
+    crate::{
+        async_engine::SpawnedFuture,
+        backend::{
+            Backend, Connector, ConnectorEvent, ConnectorId, ConnectorKernelId, InputDevice,
+            InputDeviceAccelProfile, InputDeviceCapability, InputDeviceId, InputEvent,
+            TransformMatrix,
+        },
+        compositor::TestFuture,
+        state::State,
+        utils::{clonecell::CloneCell, copyhashmap::CopyHashMap, syncqueue::SyncQueue},
+    },
+    std::{any::Any, cell::Cell, error::Error, pin::Pin, rc::Rc},
+};
+
+pub struct TestBackend {
+    pub state: Rc<State>,
+    pub test_future: TestFuture,
+}
+
+impl Backend for TestBackend {
+    fn run(self: Rc<Self>) -> SpawnedFuture<Result<(), Box<dyn Error>>> {
+        let future = (self.test_future)(&self.state);
+        self.state.eng.spawn(async move {
+            let future: Pin<_> = future.into();
+            future.await;
+            Ok(())
+        })
+    }
+
+    fn into_any(self: Rc<Self>) -> Rc<dyn Any> {
+        self
+    }
+
+    fn switch_to(&self, vtnr: u32) {
+        let _ = vtnr;
+    }
+
+    fn set_idle(&self, _idle: bool) {}
+
+    fn supports_idle(&self) -> bool {
+        true
+    }
+
+    fn supports_presentation_feedback(&self) -> bool {
+        true
+    }
+}
+
+pub struct TestConnector {
+    pub id: ConnectorId,
+    pub kernel_id: ConnectorKernelId,
+    pub events: SyncQueue<ConnectorEvent>,
+    pub on_change: CloneCell<Option<Rc<dyn Fn()>>>,
+}
+
+impl Connector for TestConnector {
+    fn id(&self) -> ConnectorId {
+        self.id
+    }
+
+    fn kernel_id(&self) -> ConnectorKernelId {
+        self.kernel_id
+    }
+
+    fn event(&self) -> Option<ConnectorEvent> {
+        self.events.pop()
+    }
+
+    fn on_change(&self, cb: Rc<dyn Fn()>) {
+        self.on_change.set(Some(cb));
+    }
+
+    fn damage(&self) {
+        todo!()
+    }
+}
+
+pub struct TestInputDevice {
+    pub id: InputDeviceId,
+    pub remove: Cell<bool>,
+    pub events: SyncQueue<InputEvent>,
+    pub on_change: CloneCell<Option<Rc<dyn Fn()>>>,
+    pub capabilities: CopyHashMap<InputDeviceCapability, ()>,
+    pub transform_matrix: Cell<TransformMatrix>,
+    pub name: Rc<String>,
+    pub accel_speed: Cell<f64>,
+    pub accel_profile: Cell<InputDeviceAccelProfile>,
+    pub left_handed: Cell<bool>,
+}
+
+impl InputDevice for TestInputDevice {
+    fn id(&self) -> InputDeviceId {
+        self.id
+    }
+
+    fn removed(&self) -> bool {
+        self.remove.get()
+    }
+
+    fn event(&self) -> Option<InputEvent> {
+        self.events.pop()
+    }
+
+    fn on_change(&self, cb: Rc<dyn Fn()>) {
+        self.on_change.set(Some(cb));
+    }
+
+    fn grab(&self, _grab: bool) {
+        // nothing
+    }
+
+    fn has_capability(&self, cap: InputDeviceCapability) -> bool {
+        self.capabilities.contains(&cap)
+    }
+
+    fn set_left_handed(&self, left_handed: bool) {
+        self.left_handed.set(left_handed);
+    }
+
+    fn set_accel_profile(&self, profile: InputDeviceAccelProfile) {
+        self.accel_profile.set(profile);
+    }
+
+    fn set_accel_speed(&self, speed: f64) {
+        self.accel_speed.set(speed)
+    }
+
+    fn set_transform_matrix(&self, matrix: TransformMatrix) {
+        self.transform_matrix.set(matrix);
+    }
+
+    fn name(&self) -> Rc<String> {
+        self.name.clone()
+    }
+}
diff --git a/src/it/test_client.rs b/src/it/test_client.rs
new file mode 100644
index 00000000..5e42b1e9
--- /dev/null
+++ b/src/it/test_client.rs
@@ -0,0 +1,34 @@
+use {
+    crate::{
+        client::Client,
+        it::{
+            test_ifs::{
+                test_compositor::TestCompositor, test_jay_compositor::TestJayCompositor,
+                test_registry::TestRegistry, test_shm::TestShm,
+            },
+            test_transport::TestTransport,
+            testrun::TestRun,
+        },
+    },
+    std::rc::Rc,
+};
+
+pub struct TestClient {
+    pub run: Rc<TestRun>,
+    pub server: Rc<Client>,
+    pub transport: Rc<TestTransport>,
+    pub registry: Rc<TestRegistry>,
+    pub jc: Rc<TestJayCompositor>,
+    pub comp: Rc<TestCompositor>,
+    pub shm: Rc<TestShm>,
+}
+
+impl TestClient {
+    pub fn error(&self, msg: &str) {
+        self.transport.error(msg)
+    }
+
+    pub async fn sync(self: &Rc<Self>) {
+        self.transport.sync().await
+    }
+}
diff --git a/src/it/test_error.rs b/src/it/test_error.rs
new file mode 100644
index 00000000..d73d37fc
--- /dev/null
+++ b/src/it/test_error.rs
@@ -0,0 +1,136 @@
+use {
+    crate::utils::errorfmt::ErrorFmt,
+    std::{
+        error::Error,
+        fmt::{Debug, Display, Formatter},
+    },
+};
+
+pub struct TestError {
+    error: Box<dyn Error + 'static>,
+    source: Option<Box<TestError>>,
+}
+
+impl TestError {
+    pub fn new<D: Display + 'static>(d: D) -> Self {
+        Self {
+            error: Box::new(DisplayError { msg: d }),
+            source: None,
+        }
+    }
+}
+
+struct DisplayError<T: Display> {
+    msg: T,
+}
+
+impl<T: Display> Debug for DisplayError<T> {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        Display::fmt(&self.msg, f)
+    }
+}
+
+impl<T: Display> Display for DisplayError<T> {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        Display::fmt(&self.msg, f)
+    }
+}
+
+impl<T: Display> Error for DisplayError<T> {}
+
+impl Debug for TestError {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("TestError")
+            .field("error", &self.error)
+            .field("source", &self.source)
+            .finish()
+    }
+}
+
+impl Display for TestError {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        let mut e_prev = self;
+        let mut e_opt = Some(self);
+        let mut first = true;
+        while let Some(e) = e_opt {
+            if first {
+                write!(f, "{}", e.error)?;
+                first = false;
+            } else {
+                write!(f, ": {}", e.error)?;
+            }
+            e_prev = e;
+            e_opt = e.source.as_deref();
+        }
+        if let Some(e) = e_prev.error.source() {
+            write!(f, ": ")?;
+            ErrorFmt(e).fmt(f)?;
+        }
+        Ok(())
+    }
+}
+
+impl<T: Error + 'static> From<T> for TestError {
+    fn from(error: T) -> Self {
+        Self {
+            error: Box::new(error),
+            source: None,
+        }
+    }
+}
+
+pub trait TestErrorExt {
+    type Context;
+
+    fn with_context<T, F>(self, f: F) -> Self::Context
+    where
+        T: Display + 'static,
+        F: FnOnce() -> T;
+}
+
+impl<T, E> TestErrorExt for Result<T, E>
+where
+    E: StdError,
+{
+    type Context = Result<T, TestError>;
+
+    fn with_context<D, F>(self, f: F) -> Self::Context
+    where
+        D: Display + 'static,
+        F: FnOnce() -> D,
+    {
+        match self {
+            Ok(v) => Ok(v),
+            Err(e) => Err(e.with_context(f())),
+        }
+    }
+}
+
+pub trait StdError: 'static {
+    fn with_context<D: Display + 'static>(self, d: D) -> TestError;
+}
+
+impl<E: Error + 'static> StdError for E {
+    fn with_context<D: Display + 'static>(self, d: D) -> TestError {
+        TestError {
+            error: Box::new(DisplayError { msg: d }),
+            source: Some(Box::new(self.into())),
+        }
+    }
+}
+
+impl StdError for TestError {
+    fn with_context<D: Display + 'static>(self, d: D) -> TestError {
+        TestError {
+            error: Box::new(DisplayError { msg: d }),
+            source: Some(Box::new(self)),
+        }
+    }
+}
+
+macro_rules! bail {
+    ($($tt:tt)*) => {{
+        let msg = format!($($tt)*);
+        return Err(crate::it::test_error::TestError::new(msg));
+    }}
+}
diff --git a/src/it/test_ifs.rs b/src/it/test_ifs.rs
new file mode 100644
index 00000000..089ed624
--- /dev/null
+++ b/src/it/test_ifs.rs
@@ -0,0 +1,8 @@
+pub mod test_callback;
+pub mod test_compositor;
+pub mod test_display;
+pub mod test_jay_compositor;
+pub mod test_registry;
+pub mod test_shm;
+pub mod test_shm_buffer;
+pub mod test_shm_pool;
diff --git a/src/it/test_ifs/test_callback.rs b/src/it/test_ifs/test_callback.rs
new file mode 100644
index 00000000..1a1f88c2
--- /dev/null
+++ b/src/it/test_ifs/test_callback.rs
@@ -0,0 +1,45 @@
+use {
+    crate::{
+        it::{
+            test_error::TestError, test_object::TestObject, test_transport::TestTransport,
+            testrun::ParseFull,
+        },
+        utils::buffd::MsgParser,
+        wire::{wl_callback::*, WlCallbackId},
+    },
+    std::{cell::Cell, rc::Rc},
+};
+
+pub struct TestCallback {
+    pub id: WlCallbackId,
+    pub transport: Rc<TestTransport>,
+    pub handler: Cell<Option<Box<dyn FnOnce()>>>,
+    pub done: Cell<bool>,
+}
+
+impl TestCallback {
+    fn handle_done(&self, parser: MsgParser<'_, '_>) -> Result<(), TestError> {
+        let _ev = Done::parse_full(parser)?;
+        self.dispatch();
+        Ok(())
+    }
+
+    fn dispatch(&self) {
+        self.done.set(true);
+        if let Some(handler) = self.handler.take() {
+            handler();
+        }
+    }
+}
+
+test_object! {
+    TestCallback, WlCallback;
+
+    DONE => handle_done,
+}
+
+impl TestObject for TestCallback {
+    fn on_remove(&self, _transport: &TestTransport) {
+        self.dispatch();
+    }
+}
diff --git a/src/it/test_ifs/test_compositor.rs b/src/it/test_ifs/test_compositor.rs
new file mode 100644
index 00000000..c6a57971
--- /dev/null
+++ b/src/it/test_ifs/test_compositor.rs
@@ -0,0 +1,18 @@
+use {
+    crate::{
+        it::{test_object::TestObject, test_transport::TestTransport},
+        wire::WlCompositorId,
+    },
+    std::rc::Rc,
+};
+
+pub struct TestCompositor {
+    pub id: WlCompositorId,
+    pub transport: Rc<TestTransport>,
+}
+
+test_object! {
+    TestCompositor, WlCompositor;
+}
+
+impl TestObject for TestCompositor {}
diff --git a/src/it/test_ifs/test_display.rs b/src/it/test_ifs/test_display.rs
new file mode 100644
index 00000000..11c4e510
--- /dev/null
+++ b/src/it/test_ifs/test_display.rs
@@ -0,0 +1,55 @@
+use {
+    crate::{
+        it::{
+            test_error::TestError, test_object::TestObject, test_transport::TestTransport,
+            testrun::ParseFull,
+        },
+        object::ObjectId,
+        utils::buffd::MsgParser,
+        wire::{wl_display::*, WlDisplayId},
+    },
+    std::rc::Rc,
+};
+
+pub struct TestDisplay {
+    pub transport: Rc<TestTransport>,
+    pub id: WlDisplayId,
+}
+
+impl TestDisplay {
+    fn handle_error(&self, parser: MsgParser<'_, '_>) -> Result<(), TestError> {
+        let ev = Error::parse_full(parser)?;
+        let msg = format!("Compositor sent an error: {}", ev.message);
+        self.transport.error(&msg);
+        self.transport.kill();
+        Ok(())
+    }
+
+    fn handle_delete_id(&self, parser: MsgParser<'_, '_>) -> Result<(), TestError> {
+        let ev = DeleteId::parse_full(parser)?;
+        match self.transport.objects.remove(&ObjectId::from_raw(ev.id)) {
+            None => {
+                let msg = format!(
+                    "Compositor sent delete_id for object {} which does not exist",
+                    ev.id
+                );
+                self.transport.error(&msg);
+                self.transport.kill();
+            }
+            Some(obj) => {
+                obj.on_remove(&self.transport);
+                self.transport.obj_ids.borrow_mut().release(ev.id);
+            }
+        }
+        Ok(())
+    }
+}
+
+test_object! {
+    TestDisplay, WlDisplay;
+
+    ERROR => handle_error,
+    DELETE_ID => handle_delete_id,
+}
+
+impl TestObject for TestDisplay {}
diff --git a/src/it/test_ifs/test_jay_compositor.rs b/src/it/test_ifs/test_jay_compositor.rs
new file mode 100644
index 00000000..0e28c2ce
--- /dev/null
+++ b/src/it/test_ifs/test_jay_compositor.rs
@@ -0,0 +1,48 @@
+use {
+    crate::{
+        client::ClientId,
+        it::{
+            test_error::TestError, test_object::TestObject, test_transport::TestTransport,
+            testrun::ParseFull,
+        },
+        utils::buffd::MsgParser,
+        wire::{
+            jay_compositor::{self, *},
+            JayCompositorId,
+        },
+    },
+    std::{cell::Cell, rc::Rc},
+};
+
+pub struct TestJayCompositor {
+    pub id: JayCompositorId,
+    pub transport: Rc<TestTransport>,
+    pub client_id: Cell<Option<ClientId>>,
+}
+
+impl TestJayCompositor {
+    pub async fn get_client_id(&self) -> Result<ClientId, TestError> {
+        if self.client_id.get().is_none() {
+            self.transport.send(GetClientId { self_id: self.id });
+        }
+        self.transport.sync().await;
+        match self.client_id.get() {
+            Some(c) => Ok(c),
+            _ => bail!("Compositor did not send a client id"),
+        }
+    }
+
+    fn handle_client_id(&self, parser: MsgParser<'_, '_>) -> Result<(), TestError> {
+        let ev = jay_compositor::ClientId::parse_full(parser)?;
+        self.client_id.set(Some(ClientId::from_raw(ev.client_id)));
+        Ok(())
+    }
+}
+
+test_object! {
+    TestJayCompositor, JayCompositor;
+
+    CLIENT_ID => handle_client_id,
+}
+
+impl TestObject for TestJayCompositor {}
diff --git a/src/it/test_ifs/test_registry.rs b/src/it/test_ifs/test_registry.rs
new file mode 100644
index 00000000..d31fb5f9
--- /dev/null
+++ b/src/it/test_ifs/test_registry.rs
@@ -0,0 +1,185 @@
+use {
+    crate::{
+        it::{
+            test_error::TestError,
+            test_ifs::{
+                test_compositor::TestCompositor, test_jay_compositor::TestJayCompositor,
+                test_shm::TestShm,
+            },
+            test_object::TestObject,
+            test_transport::TestTransport,
+            testrun::ParseFull,
+        },
+        utils::{buffd::MsgParser, clonecell::CloneCell, copyhashmap::CopyHashMap},
+        wire::{wl_registry::*, WlRegistryId},
+    },
+    std::{cell::Cell, rc::Rc},
+};
+
+pub struct TestGlobal {
+    pub name: u32,
+    pub interface: String,
+    pub version: u32,
+}
+
+pub struct TestRegistrySingletons {
+    pub jay_compositor: u32,
+    pub wl_compositor: u32,
+    pub wl_shm: u32,
+}
+
+pub struct TestRegistry {
+    pub id: WlRegistryId,
+    pub transport: Rc<TestTransport>,
+    pub globals: CopyHashMap<u32, Rc<TestGlobal>>,
+    pub singletons: CloneCell<Option<Rc<TestRegistrySingletons>>>,
+    pub jay_compositor: CloneCell<Option<Rc<TestJayCompositor>>>,
+    pub compositor: CloneCell<Option<Rc<TestCompositor>>>,
+    pub shm: CloneCell<Option<Rc<TestShm>>>,
+}
+
+macro_rules! singleton {
+    ($field:expr) => {
+        if let Some(s) = $field.get() {
+            return Ok(s);
+        }
+    };
+}
+
+impl TestRegistry {
+    pub async fn get_singletons(&self) -> Result<Rc<TestRegistrySingletons>, TestError> {
+        singleton!(self.singletons);
+        self.transport.sync().await;
+        singleton!(self.singletons);
+        let mut jay_compositor = 0;
+        let mut wl_compositor = 0;
+        let mut wl_shm = 0;
+        for global in self.globals.lock().values() {
+            match global.interface.as_str() {
+                "jay_compositor" => jay_compositor = global.name,
+                "wl_compositor" => wl_compositor = global.name,
+                "wl_shm" => wl_shm = global.name,
+                _ => {}
+            }
+        }
+        macro_rules! singleton {
+            ($($name:ident,)*) => {
+                TestRegistrySingletons {
+                    $(
+                        $name: {
+                            if $name == 0 {
+                                bail!("Compositor did not send {} singleton", stringify!($name));
+                            }
+                            $name
+                        },
+                    )*
+                }
+            }
+        }
+        let singletons = Rc::new(singleton! {
+            jay_compositor,
+            wl_compositor,
+            wl_shm,
+        });
+        self.singletons.set(Some(singletons.clone()));
+        Ok(singletons)
+    }
+
+    pub async fn get_jay_compositor(&self) -> Result<Rc<TestJayCompositor>, TestError> {
+        singleton!(self.jay_compositor);
+        let singletons = self.get_singletons().await?;
+        singleton!(self.jay_compositor);
+        let jc = Rc::new(TestJayCompositor {
+            id: self.transport.id(),
+            transport: self.transport.clone(),
+            client_id: Default::default(),
+        });
+        self.bind(&jc, singletons.jay_compositor, 1)?;
+        self.jay_compositor.set(Some(jc.clone()));
+        Ok(jc)
+    }
+
+    pub async fn get_compositor(&self) -> Result<Rc<TestCompositor>, TestError> {
+        singleton!(self.compositor);
+        let singletons = self.get_singletons().await?;
+        singleton!(self.compositor);
+        let jc = Rc::new(TestCompositor {
+            id: self.transport.id(),
+            transport: self.transport.clone(),
+        });
+        self.bind(&jc, singletons.wl_compositor, 4)?;
+        self.compositor.set(Some(jc.clone()));
+        Ok(jc)
+    }
+
+    pub async fn get_shm(&self) -> Result<Rc<TestShm>, TestError> {
+        singleton!(self.shm);
+        let singletons = self.get_singletons().await?;
+        singleton!(self.shm);
+        let jc = Rc::new(TestShm {
+            id: self.transport.id(),
+            transport: self.transport.clone(),
+            formats: Default::default(),
+            formats_awaited: Cell::new(false),
+        });
+        self.bind(&jc, singletons.wl_shm, 1)?;
+        self.shm.set(Some(jc.clone()));
+        Ok(jc)
+    }
+
+    pub fn bind<O: TestObject>(
+        &self,
+        obj: &Rc<O>,
+        name: u32,
+        version: u32,
+    ) -> Result<(), TestError> {
+        self.transport.send(Bind {
+            self_id: self.id,
+            name,
+            interface: obj.interface().name(),
+            version,
+            id: obj.id().into(),
+        });
+        self.transport.add_obj(obj.clone())?;
+        Ok(())
+    }
+
+    fn handle_global(&self, parser: MsgParser<'_, '_>) -> Result<(), TestError> {
+        let ev = Global::parse_full(parser)?;
+        let prev = self.globals.set(
+            ev.name,
+            Rc::new(TestGlobal {
+                name: ev.name,
+                interface: ev.interface.to_string(),
+                version: ev.version,
+            }),
+        );
+        if prev.is_some() {
+            self.transport.error(&format!(
+                "Compositor sent global {} multiple times",
+                ev.name
+            ));
+        }
+        Ok(())
+    }
+
+    fn handle_global_remove(&self, parser: MsgParser<'_, '_>) -> Result<(), TestError> {
+        let ev = GlobalRemove::parse_full(parser)?;
+        if self.globals.remove(&ev.name).is_none() {
+            self.transport.error(&format!(
+                "Compositor sent global_remove for {} which does not exist",
+                ev.name
+            ));
+        }
+        Ok(())
+    }
+}
+
+test_object! {
+    TestRegistry, WlRegistry;
+
+    GLOBAL => handle_global,
+    GLOBAL_REMOVE => handle_global_remove,
+}
+
+impl TestObject for TestRegistry {}
diff --git a/src/it/test_ifs/test_shm.rs b/src/it/test_ifs/test_shm.rs
new file mode 100644
index 00000000..8c4f5f77
--- /dev/null
+++ b/src/it/test_ifs/test_shm.rs
@@ -0,0 +1,59 @@
+use {
+    crate::{
+        it::{
+            test_error::TestError, test_ifs::test_shm_pool::TestShmPool, test_mem::TestMem,
+            test_object::TestObject, test_transport::TestTransport, testrun::ParseFull,
+        },
+        utils::{buffd::MsgParser, clonecell::CloneCell, copyhashmap::CopyHashMap},
+        wire::{wl_shm::*, WlShmId},
+    },
+    std::{cell::Cell, rc::Rc},
+};
+
+pub struct TestShm {
+    pub id: WlShmId,
+    pub transport: Rc<TestTransport>,
+    pub formats: CopyHashMap<u32, ()>,
+    pub formats_awaited: Cell<bool>,
+}
+
+impl TestShm {
+    pub async fn formats(&self) -> &CopyHashMap<u32, ()> {
+        if !self.formats_awaited.replace(true) {
+            self.transport.sync().await;
+        }
+        &self.formats
+    }
+
+    pub fn create_pool(&self, size: usize) -> Result<Rc<TestShmPool>, TestError> {
+        let mem = TestMem::new(size)?;
+        let pool = Rc::new(TestShmPool {
+            id: self.transport.id(),
+            transport: self.transport.clone(),
+            mem: CloneCell::new(mem.clone()),
+            destroyed: Cell::new(false),
+        });
+        self.transport.send(CreatePool {
+            self_id: self.id,
+            id: pool.id,
+            fd: mem.fd.clone(),
+            size: size as _,
+        });
+        self.transport.add_obj(pool.clone())?;
+        Ok(pool)
+    }
+
+    fn handle_format(&self, parser: MsgParser<'_, '_>) -> Result<(), TestError> {
+        let ev = Format::parse_full(parser)?;
+        self.formats.set(ev.format, ());
+        Ok(())
+    }
+}
+
+test_object! {
+    TestShm, WlShm;
+
+    FORMAT => handle_format,
+}
+
+impl TestObject for TestShm {}
diff --git a/src/it/test_ifs/test_shm_buffer.rs b/src/it/test_ifs/test_shm_buffer.rs
new file mode 100644
index 00000000..54510df1
--- /dev/null
+++ b/src/it/test_ifs/test_shm_buffer.rs
@@ -0,0 +1,61 @@
+use {
+    crate::{
+        it::{
+            test_error::TestError, test_mem::TestMem, test_object::TestObject,
+            test_transport::TestTransport, testrun::ParseFull,
+        },
+        utils::buffd::MsgParser,
+        wire::{wl_buffer::*, WlBufferId},
+    },
+    std::{
+        cell::Cell,
+        ops::{Deref, Range},
+        rc::Rc,
+    },
+};
+
+pub struct TestShmBuffer {
+    pub id: WlBufferId,
+    pub transport: Rc<TestTransport>,
+    pub range: Range<usize>,
+    pub mem: Rc<TestMem>,
+    pub released: Cell<bool>,
+    pub destroyed: Cell<bool>,
+}
+
+impl TestShmBuffer {
+    pub fn destroy(&self) {
+        if self.destroyed.replace(true) {
+            return;
+        }
+        self.transport.send(Destroy { self_id: self.id });
+    }
+
+    fn handle_release(&self, parser: MsgParser<'_, '_>) -> Result<(), TestError> {
+        let _ev = Release::parse_full(parser)?;
+        self.released.set(true);
+        Ok(())
+    }
+}
+
+impl Deref for TestShmBuffer {
+    type Target = [Cell<u8>];
+
+    fn deref(&self) -> &Self::Target {
+        &self.mem[self.range.clone()]
+    }
+}
+
+impl Drop for TestShmBuffer {
+    fn drop(&mut self) {
+        self.destroy();
+    }
+}
+
+test_object! {
+    TestShmBuffer, WlBuffer;
+
+    RELEASE => handle_release,
+}
+
+impl TestObject for TestShmBuffer {}
diff --git a/src/it/test_ifs/test_shm_pool.rs b/src/it/test_ifs/test_shm_pool.rs
new file mode 100644
index 00000000..a58dbb81
--- /dev/null
+++ b/src/it/test_ifs/test_shm_pool.rs
@@ -0,0 +1,86 @@
+use {
+    crate::{
+        format::Format,
+        it::{
+            test_error::TestError, test_ifs::test_shm_buffer::TestShmBuffer, test_mem::TestMem,
+            test_object::TestObject, test_transport::TestTransport,
+        },
+        utils::clonecell::CloneCell,
+        wire::{wl_shm_pool::*, WlShmPoolId},
+    },
+    std::{cell::Cell, rc::Rc},
+};
+
+pub struct TestShmPool {
+    pub id: WlShmPoolId,
+    pub transport: Rc<TestTransport>,
+    pub mem: CloneCell<Rc<TestMem>>,
+    pub destroyed: Cell<bool>,
+}
+
+impl TestShmPool {
+    pub fn create_buffer(
+        &self,
+        offset: i32,
+        width: i32,
+        height: i32,
+        stride: i32,
+        format: &Format,
+    ) -> Result<Rc<TestShmBuffer>, TestError> {
+        let size = (height * stride) as usize;
+        let start = offset as usize;
+        let end = start + size;
+        let mem = self.mem.get();
+        if end > mem.len() {
+            bail!("Out-of-bounds buffer");
+        }
+        let buffer = Rc::new(TestShmBuffer {
+            id: self.transport.id(),
+            transport: self.transport.clone(),
+            range: start..end,
+            mem,
+            released: Cell::new(true),
+            destroyed: Cell::new(false),
+        });
+        self.transport.add_obj(buffer.clone())?;
+        self.transport.send(CreateBuffer {
+            self_id: self.id,
+            id: buffer.id,
+            offset,
+            width,
+            height,
+            stride,
+            format: format.wl_id.unwrap_or(format.drm),
+        });
+        Ok(buffer)
+    }
+
+    pub fn resize(&self, size: usize) -> Result<(), TestError> {
+        let mem = self.mem.get().grow(size)?;
+        self.mem.set(mem);
+        self.transport.send(Resize {
+            self_id: self.id,
+            size: size as _,
+        });
+        Ok(())
+    }
+
+    pub fn destroy(&self) {
+        if self.destroyed.replace(true) {
+            return;
+        }
+        self.transport.send(Destroy { self_id: self.id });
+    }
+}
+
+impl Drop for TestShmPool {
+    fn drop(&mut self) {
+        self.destroy()
+    }
+}
+
+test_object! {
+    TestShmPool, WlShmPool;
+}
+
+impl TestObject for TestShmPool {}
diff --git a/src/it/test_logger.rs b/src/it/test_logger.rs
new file mode 100644
index 00000000..669ed8c3
--- /dev/null
+++ b/src/it/test_logger.rs
@@ -0,0 +1,73 @@
+use {
+    crate::utils::clonecell::CloneCell,
+    log::{Level, LevelFilter, Log, Metadata, Record},
+    std::{cell::Cell, fmt::Write as FmtWrite, io::Write, rc::Rc, time::SystemTime},
+    uapi::{Fd, OwnedFd},
+};
+
+#[thread_local]
+static LEVEL: Cell<Level> = Cell::new(Level::Info);
+
+#[thread_local]
+static FILE: CloneCell<Option<Rc<OwnedFd>>> = CloneCell::new(None);
+
+pub fn install() {
+    log::set_logger(&Logger).unwrap();
+    log::set_max_level(LevelFilter::Info);
+}
+
+pub fn set_level(level: Level) {
+    LEVEL.set(level);
+    log::set_max_level(level.to_level_filter());
+}
+
+pub fn set_file(file: Rc<OwnedFd>) {
+    FILE.set(Some(file));
+}
+
+pub fn unset_file() {
+    FILE.set(None);
+}
+
+struct Logger;
+
+impl Log for Logger {
+    fn enabled(&self, metadata: &Metadata) -> bool {
+        metadata.level() <= LEVEL.get()
+    }
+
+    fn log(&self, record: &Record) {
+        if record.level() > LEVEL.get() {
+            return;
+        }
+        let mut buf = String::new();
+        let now = SystemTime::now();
+        let _ = if let Some(mp) = record.module_path() {
+            writeln!(
+                buf,
+                "[{} {:5} {}] {}",
+                humantime::format_rfc3339_millis(now),
+                record.level(),
+                mp,
+                record.args(),
+            )
+        } else {
+            writeln!(
+                buf,
+                "[{} {:5}] {}",
+                humantime::format_rfc3339_millis(now),
+                record.level(),
+                record.args(),
+            )
+        };
+        let mut fd = match FILE.get() {
+            Some(f) => f.borrow(),
+            _ => Fd::new(2),
+        };
+        let _ = fd.write_all(buf.as_bytes());
+    }
+
+    fn flush(&self) {
+        // nothing
+    }
+}
diff --git a/src/it/test_mem.rs b/src/it/test_mem.rs
new file mode 100644
index 00000000..e7e608d2
--- /dev/null
+++ b/src/it/test_mem.rs
@@ -0,0 +1,71 @@
+use {
+    crate::{
+        it::test_error::TestError,
+        utils::{oserror::OsError, ptr_ext::PtrExt},
+    },
+    std::{cell::Cell, ops::Deref, ptr, rc::Rc},
+    uapi::{c, OwnedFd},
+};
+
+pub struct TestMem {
+    pub fd: Rc<OwnedFd>,
+    slice: *const [Cell<u8>],
+}
+
+impl TestMem {
+    pub fn new(size: usize) -> Result<Rc<Self>, TestError> {
+        let fd = uapi::memfd_create("test_pool", c::MFD_CLOEXEC | c::MFD_ALLOW_SEALING)?;
+        uapi::fcntl_add_seals(fd.raw(), c::F_SEAL_SHRINK)?;
+        uapi::ftruncate(fd.raw(), size as _)?;
+        let slice = map(fd.raw(), size)?;
+        Ok(Rc::new(Self {
+            fd: Rc::new(fd),
+            slice,
+        }))
+    }
+
+    pub fn grow(&self, size: usize) -> Result<Rc<Self>, TestError> {
+        let cur_len = uapi::fstat(self.fd.raw())?;
+        if size > cur_len.st_size as _ {
+            uapi::ftruncate(self.fd.raw(), size as _)?;
+        }
+        let slice = map(self.fd.raw(), size)?;
+        Ok(Rc::new(Self {
+            fd: self.fd.clone(),
+            slice,
+        }))
+    }
+}
+
+impl Deref for TestMem {
+    type Target = [Cell<u8>];
+
+    fn deref(&self) -> &Self::Target {
+        unsafe { &*self.slice }
+    }
+}
+
+fn map(fd: c::c_int, size: usize) -> Result<*const [Cell<u8>], TestError> {
+    unsafe {
+        let res = c::mmap(
+            ptr::null_mut(),
+            size as _,
+            c::PROT_READ | c::PROT_WRITE,
+            c::MAP_SHARED,
+            fd,
+            0,
+        );
+        if res == c::MAP_FAILED {
+            bail!("Could not map memory: {}", OsError::default());
+        }
+        Ok(std::slice::from_raw_parts(res as _, size))
+    }
+}
+
+impl Drop for TestMem {
+    fn drop(&mut self) {
+        unsafe {
+            c::munmap(self.slice.deref().as_ptr() as _, self.slice.deref().len());
+        }
+    }
+}
diff --git a/src/it/test_object.rs b/src/it/test_object.rs
new file mode 100644
index 00000000..95c5038a
--- /dev/null
+++ b/src/it/test_object.rs
@@ -0,0 +1,54 @@
+use {
+    crate::{
+        it::{test_error::TestError, test_transport::TestTransport},
+        object::{Interface, ObjectId},
+        utils::buffd::MsgParser,
+    },
+    std::rc::Rc,
+};
+
+macro_rules! test_object {
+    ($oname:ident, $ifname:ident; $($code:ident => $f:ident,)*) => {
+        impl crate::it::test_object::TestObjectBase for $oname {
+            fn id(&self) -> crate::object::ObjectId {
+                self.id.into()
+            }
+
+            #[allow(unused_variables, unreachable_code)]
+            fn handle_request(
+                self: std::rc::Rc<Self>,
+                request: u32,
+                parser: crate::utils::buffd::MsgParser<'_, '_>,
+            ) -> Result<(), crate::it::test_error::TestError> {
+                use crate::it::test_error::TestErrorExt;
+                let res: Result<(), crate::it::test_error::TestError> = match request {
+                    $(
+                        $code => $oname::$f(&self, parser).with_context(|| format!("While handling a `{}` event", stringify!($f))),
+                    )*
+                    _ => Err(crate::it::test_error::TestError::new("Unknown event {}")),
+                };
+                res.with_context(|| format!("In object {} of type `{}`", self.id(), self.interface().name()))
+            }
+
+            fn interface(&self) -> crate::object::Interface {
+                crate::wire::$ifname
+            }
+        }
+    };
+}
+
+pub trait TestObjectBase: 'static {
+    fn id(&self) -> ObjectId;
+    fn handle_request(
+        self: Rc<Self>,
+        request: u32,
+        parser: MsgParser<'_, '_>,
+    ) -> Result<(), TestError>;
+    fn interface(&self) -> Interface;
+}
+
+pub trait TestObject: TestObjectBase {
+    fn on_remove(&self, transport: &TestTransport) {
+        let _ = transport;
+    }
+}
diff --git a/src/it/test_transport.rs b/src/it/test_transport.rs
new file mode 100644
index 00000000..d842096e
--- /dev/null
+++ b/src/it/test_transport.rs
@@ -0,0 +1,254 @@
+use {
+    crate::{
+        async_engine::{AsyncFd, SpawnedFuture},
+        client::{ClientId, EventFormatter},
+        it::{
+            test_error::{StdError, TestError},
+            test_ifs::{test_callback::TestCallback, test_registry::TestRegistry},
+            test_object::TestObject,
+            testrun::TestRun,
+        },
+        object::{ObjectId, WL_DISPLAY_ID},
+        utils::{
+            asyncevent::AsyncEvent,
+            bitfield::Bitfield,
+            buffd::{BufFdIn, BufFdOut, MsgFormatter, MsgParser, OutBuffer, OutBufferSwapchain},
+            copyhashmap::CopyHashMap,
+            stack::Stack,
+            vec_ext::VecExt,
+        },
+        wire::wl_display,
+    },
+    std::{
+        cell::{Cell, RefCell},
+        collections::VecDeque,
+        future::Future,
+        mem,
+        rc::Rc,
+        task::Poll,
+    },
+};
+
+pub struct TestTransport {
+    pub run: Rc<TestRun>,
+    pub fd: AsyncFd,
+    pub client_id: Cell<ClientId>,
+    pub bufs: Stack<Vec<u32>>,
+    pub swapchain: Rc<RefCell<OutBufferSwapchain>>,
+    pub flush_request: AsyncEvent,
+    pub incoming: Cell<Option<SpawnedFuture<()>>>,
+    pub outgoing: Cell<Option<SpawnedFuture<()>>>,
+    pub objects: CopyHashMap<ObjectId, Rc<dyn TestObject>>,
+    pub obj_ids: RefCell<Bitfield>,
+    pub killed: Cell<bool>,
+}
+
+impl TestTransport {
+    pub fn get_registry(self: &Rc<Self>) -> Rc<TestRegistry> {
+        let reg = Rc::new(TestRegistry {
+            id: self.id(),
+            transport: self.clone(),
+            globals: Default::default(),
+            singletons: Default::default(),
+            jay_compositor: Default::default(),
+            compositor: Default::default(),
+            shm: Default::default(),
+        });
+        self.send(wl_display::GetRegistry {
+            self_id: WL_DISPLAY_ID,
+            registry: reg.id,
+        });
+        let _ = self.add_obj(reg.clone());
+        reg
+    }
+
+    pub fn add_obj(&self, obj: Rc<dyn TestObject>) -> Result<(), TestError> {
+        if self.killed.get() {
+            bail!("Transport has already been killed");
+        }
+        let id = obj.id();
+        if self.objects.set(id, obj).is_some() {
+            bail!("There already is an object with id {}", id);
+        }
+        Ok(())
+    }
+
+    pub fn kill(&self) {
+        self.outgoing.take();
+        self.incoming.take();
+        for (_, object) in self.objects.lock().drain() {
+            object.on_remove(self);
+        }
+    }
+
+    pub fn sync(self: &Rc<Self>) -> impl Future<Output = ()> {
+        let cb = Rc::new(TestCallback {
+            id: self.id(),
+            transport: self.clone(),
+            handler: Cell::new(None),
+            done: Cell::new(self.killed.get()),
+        });
+        self.send(wl_display::Sync {
+            self_id: WL_DISPLAY_ID,
+            callback: cb.id,
+        });
+        let _ = self.add_obj(cb.clone());
+        futures_util::future::poll_fn(move |ctx| {
+            if cb.done.get() {
+                Poll::Ready(())
+            } else {
+                let waker = ctx.waker().clone();
+                cb.handler.set(Some(Box::new(move || waker.wake())));
+                Poll::Pending
+            }
+        })
+    }
+
+    pub fn id<T: From<ObjectId>>(&self) -> T {
+        ObjectId::from_raw(self.obj_ids.borrow_mut().acquire()).into()
+    }
+
+    pub fn error(&self, msg: &str) {
+        let msg = format!("In client {}: {}", self.client_id.get(), msg);
+        self.run.errors.push(msg);
+    }
+
+    pub fn init(self: &Rc<Self>) {
+        self.incoming.set(Some(
+            self.run.state.eng.spawn(
+                Incoming {
+                    tc: self.clone(),
+                    buf: BufFdIn::new(self.fd.clone()),
+                }
+                .run(),
+            ),
+        ));
+        self.outgoing.set(Some(
+            self.run.state.eng.spawn(
+                Outgoing {
+                    tc: self.clone(),
+                    buf: BufFdOut::new(self.fd.clone()),
+                    buffers: Default::default(),
+                }
+                .run(),
+            ),
+        ));
+    }
+
+    pub fn send<M: EventFormatter>(&self, msg: M) {
+        if self.killed.get() {
+            return;
+        }
+        let mut fds = vec![];
+        let mut swapchain = self.swapchain.borrow_mut();
+        let mut fmt = MsgFormatter::new(&mut swapchain.cur, &mut fds);
+        msg.format(&mut fmt);
+        fmt.write_len();
+        if swapchain.cur.is_full() {
+            swapchain.commit();
+        }
+        self.flush_request.trigger();
+    }
+}
+
+struct Outgoing {
+    tc: Rc<TestTransport>,
+    buf: BufFdOut,
+    buffers: VecDeque<OutBuffer>,
+}
+
+impl Outgoing {
+    async fn run(mut self: Self) {
+        loop {
+            self.tc.flush_request.triggered().await;
+            if let Err(e) = self.flush().await {
+                let msg = format!(
+                    "Could not process an outgoing message for client {}: {}",
+                    self.tc.client_id.get(),
+                    e
+                );
+                log::error!("{}", msg);
+                self.tc.run.errors.push(msg);
+                break;
+            }
+        }
+    }
+
+    async fn flush(&mut self) -> Result<(), TestError> {
+        {
+            let mut swapchain = self.tc.swapchain.borrow_mut();
+            swapchain.commit();
+            mem::swap(&mut swapchain.pending, &mut self.buffers);
+        }
+        while let Some(mut cur) = self.buffers.pop_front() {
+            if let Err(e) = self.buf.flush_no_timeout(&mut cur).await {
+                return Err(e.with_context("Could not write to wayland socket"));
+            }
+            self.tc.swapchain.borrow_mut().free.push(cur);
+        }
+        Ok(())
+    }
+}
+
+struct Incoming {
+    tc: Rc<TestTransport>,
+    buf: BufFdIn,
+}
+
+impl Incoming {
+    async fn run(mut self: Self) {
+        loop {
+            if let Err(e) = self.handle_msg().await {
+                let msg = format!(
+                    "Could not process an incoming message for client {}: {}",
+                    self.tc.client_id.get(),
+                    e
+                );
+                log::error!("{}", msg);
+                self.tc.run.errors.push(msg);
+                break;
+            }
+        }
+        self.tc.kill();
+    }
+
+    async fn handle_msg(&mut self) -> Result<(), TestError> {
+        let mut hdr = [0u32, 0];
+        if let Err(e) = self.buf.read_full(&mut hdr[..]).await {
+            return Err(e.with_context("Could not read from wayland socket"));
+        }
+        let obj_id = ObjectId::from_raw(hdr[0]);
+        let len = (hdr[1] >> 16) as usize;
+        let request = hdr[1] & 0xffff;
+        if len < 8 {
+            bail!("Message size is < 8");
+        }
+        if len % 4 != 0 {
+            bail!("Message size is not a multiple of 4");
+        }
+        let len = len / 4 - 2;
+        let mut data_buf = self.tc.bufs.pop().unwrap_or_default();
+        data_buf.clear();
+        data_buf.reserve(len);
+        let unused = data_buf.split_at_spare_mut_ext().1;
+        if let Err(e) = self.buf.read_full(&mut unused[..len]).await {
+            return Err(e.with_context("Could not read from wayland socket"));
+        }
+        unsafe {
+            data_buf.set_len(len);
+        }
+        let object = match self.tc.objects.get(&obj_id) {
+            Some(obj) => obj,
+            _ => bail!(
+                "Compositor sent a message for object {} which does not exist",
+                obj_id
+            ),
+        };
+        let parser = MsgParser::new(&mut self.buf, &data_buf);
+        object.handle_request(request, parser)?;
+        if data_buf.capacity() > 0 {
+            self.tc.bufs.push(data_buf);
+        }
+        Ok(())
+    }
+}
diff --git a/src/it/testrun.rs b/src/it/testrun.rs
new file mode 100644
index 00000000..b1b5bd94
--- /dev/null
+++ b/src/it/testrun.rs
@@ -0,0 +1,100 @@
+use {
+    crate::{
+        client::{ClientId, RequestParser},
+        it::{
+            test_backend::TestBackend,
+            test_client::TestClient,
+            test_error::{TestError, TestErrorExt},
+            test_ifs::test_display::TestDisplay,
+            test_transport::TestTransport,
+        },
+        object::WL_DISPLAY_ID,
+        state::State,
+        utils::{bitfield::Bitfield, buffd::MsgParser, oserror::OsErrorExt, stack::Stack},
+    },
+    std::{
+        cell::{Cell, RefCell},
+        rc::Rc,
+    },
+    uapi::c,
+};
+
+pub struct TestRun {
+    pub state: Rc<State>,
+    pub backend: Rc<TestBackend>,
+    pub errors: Stack<String>,
+    pub server_addr: c::sockaddr_un,
+}
+
+impl TestRun {
+    pub async fn create_client(self: &Rc<Self>) -> Result<Rc<TestClient>, TestError> {
+        self.create_client2()
+            .await
+            .with_context(|| "Could not create a client")
+    }
+
+    async fn create_client2(self: &Rc<Self>) -> Result<Rc<TestClient>, TestError> {
+        let socket = uapi::socket(
+            c::AF_UNIX,
+            c::SOCK_STREAM | c::SOCK_CLOEXEC | c::SOCK_NONBLOCK,
+            0,
+        )
+        .to_os_error()
+        .with_context(|| "Could not create a unix socket")?;
+        let socket = Rc::new(socket);
+        uapi::connect(socket.raw(), &self.server_addr)
+            .to_os_error()
+            .with_context(|| "Could not connect to the compositor")?;
+        let fd = self
+            .state
+            .eng
+            .fd(&socket)
+            .with_context(|| "Could not create an async fd")?;
+        let mut obj_ids = Bitfield::default();
+        obj_ids.take(0);
+        obj_ids.take(1);
+        let transport = Rc::new(TestTransport {
+            run: self.clone(),
+            fd,
+            client_id: Cell::new(ClientId::from_raw(0)),
+            bufs: Default::default(),
+            swapchain: Default::default(),
+            flush_request: Default::default(),
+            incoming: Default::default(),
+            outgoing: Default::default(),
+            objects: Default::default(),
+            obj_ids: RefCell::new(obj_ids),
+            killed: Cell::new(false),
+        });
+        transport.add_obj(Rc::new(TestDisplay {
+            transport: transport.clone(),
+            id: WL_DISPLAY_ID,
+        }))?;
+        transport.init();
+        let registry = transport.get_registry();
+        let jc = registry.get_jay_compositor().await?;
+        let client_id = jc.get_client_id().await?;
+        let client = self.state.clients.get(client_id)?;
+        Ok(Rc::new(TestClient {
+            run: self.clone(),
+            server: client,
+            transport,
+            jc,
+            comp: registry.get_compositor().await?,
+            shm: registry.get_shm().await?,
+            registry,
+        }))
+    }
+}
+
+pub trait ParseFull<'a>: Sized {
+    fn parse_full(parser: MsgParser<'_, 'a>) -> Result<Self, TestError>;
+}
+
+impl<'a, T: RequestParser<'a>> ParseFull<'a> for T {
+    fn parse_full(mut parser: MsgParser<'_, 'a>) -> Result<Self, TestError> {
+        let res = T::parse(&mut parser)?;
+        parser.eof()?;
+        Ok(res)
+    }
+}
diff --git a/src/it/tests.rs b/src/it/tests.rs
new file mode 100644
index 00000000..016b0384
--- /dev/null
+++ b/src/it/tests.rs
@@ -0,0 +1,47 @@
+use {
+    crate::it::{test_error::TestError, testrun::TestRun},
+    std::{future::Future, rc::Rc},
+};
+
+macro_rules! testcase {
+    () => {
+        pub struct Test;
+
+        impl crate::it::tests::TestCase for Test {
+            fn name(&self) -> &'static str {
+                module_path!().strip_prefix("jay::it::tests::").unwrap()
+            }
+
+            fn run(
+                &self,
+                testrun: std::rc::Rc<crate::it::testrun::TestRun>,
+            ) -> Box<dyn std::future::Future<Output = Result<(), TestError>>> {
+                Box::new(test(testrun))
+            }
+        }
+    };
+}
+
+macro_rules! tassert {
+    ($cond:expr) => {
+        if !$cond {
+            bail!(
+                "Assert `{}` failed ({}:{})",
+                stringify!($cond),
+                file!(),
+                line!()
+            );
+        }
+    };
+}
+
+mod t0001_shm_formats;
+
+pub trait TestCase {
+    fn name(&self) -> &'static str;
+    fn run(&self, testrun: Rc<TestRun>) -> Box<dyn Future<Output = Result<(), TestError>>>;
+}
+
+pub fn tests() -> Vec<&'static dyn TestCase> {
+    vec![&t0001_shm_formats::Test]
+}
diff --git a/src/it/tests/t0001_shm_formats.rs b/src/it/tests/t0001_shm_formats.rs
new file mode 100644
index 00000000..26117aa6
--- /dev/null
+++ b/src/it/tests/t0001_shm_formats.rs
@@ -0,0 +1,18 @@
+use {
+    crate::{
+        format::{ARGB8888, XRGB8888},
+        it::{test_error::TestError, testrun::TestRun},
+    },
+    std::rc::Rc,
+};
+
+testcase!();
+
+/// Test that wl_shm supports the required formats
+async fn test(run: Rc<TestRun>) -> Result<(), TestError> {
+    let client = run.create_client().await?;
+    let formats = client.shm.formats().await;
+    tassert!(formats.contains(&XRGB8888.wl_id.unwrap()));
+    tassert!(formats.contains(&ARGB8888.wl_id.unwrap()));
+    Ok(())
+}
diff --git a/src/main.rs b/src/main.rs
index 002967de..1d95c2cf 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -52,6 +52,7 @@ mod forker;
 mod format;
 mod globals;
 mod ifs;
+mod it;
 mod libinput;
 mod logger;
 mod logind;
diff --git a/src/state.rs b/src/state.rs
index 6e91596a..8bea1092 100644
--- a/src/state.rs
+++ b/src/state.rs
@@ -1,5 +1,6 @@
 use {
     crate::{
+        acceptor::Acceptor,
         async_engine::{AsyncEngine, SpawnedFuture},
         backend::{
             Backend, BackendEvent, Connector, ConnectorId, ConnectorIds, InputDevice,
@@ -83,14 +84,14 @@ pub struct State {
     pub pending_float_titles: AsyncQueue<Rc<FloatNode>>,
     pub dbus: Dbus,
     pub fdcloser: Arc<FdCloser>,
-    pub logger: Arc<Logger>,
+    pub logger: Option<Arc<Logger>>,
     pub connectors: CopyHashMap<ConnectorId, Rc<ConnectorData>>,
     pub outputs: CopyHashMap<ConnectorId, Rc<OutputData>>,
     pub status: CloneCell<Rc<String>>,
     pub idle: IdleState,
     pub run_args: RunArgs,
     pub xwayland: XWaylandState,
-    pub socket_path: CloneCell<Rc<String>>,
+    pub acceptor: CloneCell<Option<Rc<Acceptor>>>,
     pub serial: NumCell<Wrapping<u32>>,
     pub run_toplevel: Rc<RunToplevel>,
 }
diff --git a/src/utils/bitfield.rs b/src/utils/bitfield.rs
index 930c38f0..cdb58aa2 100644
--- a/src/utils/bitfield.rs
+++ b/src/utils/bitfield.rs
@@ -14,7 +14,7 @@ impl Bitfield {
         let idx = val as usize / SEG_SIZE;
         let pos = val as usize % SEG_SIZE;
         while self.vals.len() <= idx {
-            self.vals.push(0);
+            self.vals.push(!0);
         }
         self.vals[idx] &= !(1 << pos);
     }
diff --git a/src/utils/clonecell.rs b/src/utils/clonecell.rs
index 03d12037..90160ff9 100644
--- a/src/utils/clonecell.rs
+++ b/src/utils/clonecell.rs
@@ -12,7 +12,7 @@ use {
     },
 };
 
-pub struct CloneCell<T: UnsafeCellCloneSafe> {
+pub struct CloneCell<T> {
     data: UnsafeCell<T>,
 }
 
@@ -26,19 +26,22 @@ impl<T: UnsafeCellCloneSafe> Clone for CloneCell<T> {
 
 impl<T: UnsafeCellCloneSafe + Debug> Debug for CloneCell<T> {
     fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
-        unsafe { self.data.get().deref().fmt(f) }
+        self.get().fmt(f)
     }
 }
 
-impl<T: UnsafeCellCloneSafe> CloneCell<T> {
-    pub fn new(t: T) -> Self {
+impl<T> CloneCell<T> {
+    pub const fn new(t: T) -> Self {
         Self {
             data: UnsafeCell::new(t),
         }
     }
 
     #[inline(always)]
-    pub fn get(&self) -> T {
+    pub fn get(&self) -> T
+    where
+        T: UnsafeCellCloneSafe,
+    {
         unsafe { self.data.get().deref().clone() }
     }
 
@@ -52,7 +55,7 @@ impl<T: UnsafeCellCloneSafe> CloneCell<T> {
     where
         T: Default,
     {
-        unsafe { mem::take(self.data.get().deref_mut()) }
+        self.set(T::default())
     }
 }
 
diff --git a/src/utils/copyhashmap.rs b/src/utils/copyhashmap.rs
index 0ec070ea..0f8810cb 100644
--- a/src/utils/copyhashmap.rs
+++ b/src/utils/copyhashmap.rs
@@ -37,10 +37,8 @@ impl<K: Eq + Hash, V> CopyHashMap<K, V> {
         Self::default()
     }
 
-    pub fn set(&self, k: K, v: V) {
-        unsafe {
-            self.map.get().deref_mut().insert(k, v);
-        }
+    pub fn set(&self, k: K, v: V) -> Option<V> {
+        unsafe { self.map.get().deref_mut().insert(k, v) }
     }
 
     pub fn get<Q: ?Sized>(&self, k: &Q) -> Option<V>
diff --git a/src/utils/oserror.rs b/src/utils/oserror.rs
index 148c02bd..a0ea8f5f 100644
--- a/src/utils/oserror.rs
+++ b/src/utils/oserror.rs
@@ -204,3 +204,17 @@ impl Display for OsError {
         write!(f, "{} (os error {})", msg, self.0)
     }
 }
+
+pub trait OsErrorExt {
+    type Container;
+
+    fn to_os_error(self) -> Self::Container;
+}
+
+impl<T> OsErrorExt for Result<T, Errno> {
+    type Container = Result<T, OsError>;
+
+    fn to_os_error(self) -> Self::Container {
+        self.map_err(|e| e.into())
+    }
+}
diff --git a/src/xwayland.rs b/src/xwayland.rs
index af43cd32..6f4c8c26 100644
--- a/src/xwayland.rs
+++ b/src/xwayland.rs
@@ -100,7 +100,7 @@ pub async fn manage(state: Rc<State>) {
         forker.setenv(DISPLAY.as_bytes(), display.as_bytes());
         log::info!("Allocated display :{} for Xwayland", xsocket.id);
         log::info!("Waiting for connection attempt");
-        if state.backend.get().is_freestanding() {
+        if state.backend.get().import_environment() {
             import_environment(&state, DISPLAY, &display);
         }
         let res = XWaylandError::tria(async {
diff --git a/wire/jay_compositor.txt b/wire/jay_compositor.txt
index 90095c41..d5924dca 100644
--- a/wire/jay_compositor.txt
+++ b/wire/jay_compositor.txt
@@ -22,3 +22,13 @@ msg take_screenshot = 4 {
 msg get_idle = 5 {
     id: id(jay_idle),
 }
+
+msg get_client_id = 6 {
+
+}
+
+# events
+
+msg client_id = 0 {
+    client_id: pod(u64),
+}