it: use single-pixel buffer instead of shm

src/it/test_ifs/test_buffer.rs

@@ -0,0 +1,48 @@
+use {
+    crate::{
+        it::{
+            test_error::TestError, test_object::TestObject, test_transport::TestTransport,
+            testrun::ParseFull,
+        },
+        utils::buffd::MsgParser,
+        wire::{wl_buffer::*, WlBufferId},
+    },
+    std::{cell::Cell, rc::Rc},
+};
+
+pub struct TestBuffer {
+    pub id: WlBufferId,
+    pub tran: Rc<TestTransport>,
+    pub released: Cell<bool>,
+    pub destroyed: Cell<bool>,
+}
+
+impl TestBuffer {
+    pub fn destroy(&self) -> Result<(), TestError> {
+        if self.destroyed.replace(true) {
+            return Ok(());
+        }
+        self.tran.send(Destroy { self_id: self.id })?;
+        Ok(())
+    }
+
+    fn handle_release(&self, parser: MsgParser<'_, '_>) -> Result<(), TestError> {
+        let _ev = Release::parse_full(parser)?;
+        self.released.set(true);
+        Ok(())
+    }
+}
+
+impl Drop for TestBuffer {
+    fn drop(&mut self) {
+        let _ = self.destroy();
+    }
+}
+
+test_object! {
+    TestBuffer, WlBuffer;
+
+    RELEASE => handle_release,
+}
+
+impl TestObject for TestBuffer {}