add data verification to i2c_irq test

target/ast10x0/tests/peripherals/i2c/i2c_irq/slave_target.rs

diff --git a/target/ast10x0/tests/peripherals/i2c/i2c_irq/slave_target.rs b/target/ast10x0/tests/peripherals/i2c/i2c_irq/slave_target.rs
index 085f1af..c187718 100644
--- a/target/ast10x0/tests/peripherals/i2c/i2c_irq/slave_target.rs
+++ b/target/ast10x0/tests/peripherals/i2c/i2c_irq/slave_target.rs
@@ -90,6 +90,11 @@
                 pw_log::error!("test 1: DataReceived len={} expected={}", len as u32, EXPECTED_WRITE.len() as u32);
                 return Err("test 1: DataReceived len mismatch");
             }
+            let mut buf = [0u8; EXPECTED_WRITE.len()];
+            slave.slave_read(&mut buf).map_err(|_| "test 1: slave_read failed")?;
+            if buf != *EXPECTED_WRITE {
+                return Err("test 1: DataReceived payload mismatch");
+            }
             pw_log::info!("Test 1 passed: DataReceived len={}", len as u32);
         }
         Some(_) => return Err("test 1: unexpected slave event"),