diff --git a/crates/moon/tests/test_cases/expect_test.in/lib/hello.mbt b/crates/moon/tests/test_cases/expect_test.in/lib/hello.mbt
index 25ffa6e1..84f78b77 100644
--- a/crates/moon/tests/test_cases/expect_test.in/lib/hello.mbt
+++ b/crates/moon/tests/test_cases/expect_test.in/lib/hello.mbt
@@ -3,46 +3,46 @@ pub fn hello() -> String {
 }
 
 test "basic" {
-  let buf = Buffer::new()
+  let buf = @buffer.new()
   let n = 123
   buf.write_string(n.to_string())
-  buf.expect!()
+  inspect!(buf)
 }
 
 test "indent" {
   let _ = {
-    let buf = Buffer::new()
+    let buf = @buffer.new()
     let s = "haha"
     buf.write_string(s)
-    buf.expect!()
+    inspect!(buf)
   }
   ()
 }
 
 test "auto_reset" {
-  let buf = Buffer::new()
+  let buf = @buffer.new()
   let s = "haha"
   buf.write_string(s)
-  buf.expect!()
+  inspect!(buf)
   let s = "123"
   buf.write_string(s)
-  buf.expect!(content="123")
+  inspect!(buf, content="123")
 }
 
 test "multiline-string" {
-  let buf = Buffer::new()
+  let buf = @buffer.new()
   let s = "1\n2\n3\n"
   buf.write_string(s)
-  buf.expect!()
+  inspect!(buf)
 }
 
 test "multiline-string-2" {
-  let buf = Buffer::new()
+  let buf = @buffer.new()
   let s =
     #|abc
     #|def
   buf.write_string(s)
-  buf.expect!(
+  inspect!(buf,
     content=
       #|bcd
       #|defg
@@ -51,9 +51,9 @@ test "multiline-string-2" {
 }
 
 test "not-empty-expect" {
-  let buf = Buffer::new()
+  let buf = @buffer.new()
   buf.write_string("123")
-  buf.expect!(content="1")
+  inspect!(buf, content="1")
 }
 
 test {
@@ -128,15 +128,15 @@ test {
 }
 
 test {
-  let buf = Buffer::new()
+  let buf = @buffer.new()
   buf.write_string("just\ntest")
-  buf.expect!()
+  inspect!(buf)
 }
 
 test "hello" {
-  let buf = Buffer::new()
+  let buf = @buffer.new()
   buf.write_string("just\ntest")
-  buf.expect!(content="")
+  inspect!(buf, content="")
 }
 
 fn actual() -> String {
diff --git a/crates/moon/tests/test_cases/expect_test.in/lib/hello_wbtest.mbt b/crates/moon/tests/test_cases/expect_test.in/lib/hello_wbtest.mbt
index 62e7ad67..b6425ee0 100644
--- a/crates/moon/tests/test_cases/expect_test.in/lib/hello_wbtest.mbt
+++ b/crates/moon/tests/test_cases/expect_test.in/lib/hello_wbtest.mbt
@@ -1,11 +1,11 @@
 test "hello" {
-  let buf = Buffer::new()
+  let buf = @buffer.new()
   buf.write_string("just\ntest")
-  buf.expect!()
+  inspect!(buf)
 }
 
 test "not-buf" {
-  let notbuf = Buffer::new()
+  let notbuf = @buffer.new()
   notbuf.write_string("haha")
-  notbuf.expect!()
+  inspect!(notbuf)
 }
diff --git a/crates/moon/tests/test_cases/mod.rs b/crates/moon/tests/test_cases/mod.rs
index f2ef3e31..be07cc13 100644
--- a/crates/moon/tests/test_cases/mod.rs
+++ b/crates/moon/tests/test_cases/mod.rs
@@ -2246,7 +2246,7 @@ fn test_expect_test() -> anyhow::Result<()> {
     assert!(out.contains("Total tests: 30, passed: 30, failed: 0."));
     let out = std::fs::read_to_string(tmp_dir_path.as_ref().join("lib").join("hello_wbtest.mbt"))
         .unwrap();
-    assert!(out.contains(r#"notbuf.expect!(content="haha")"#));
+    assert!(out.contains(r#"inspect!(notbuf, content="haha")"#));
     Ok(())
 }
 
diff --git a/crates/moon/tests/test_cases/moon_run_with_cli_args.in/main/main_wasm.mbt b/crates/moon/tests/test_cases/moon_run_with_cli_args.in/main/main_wasm.mbt
index c02d3958..aa100243 100644
--- a/crates/moon/tests/test_cases/moon_run_with_cli_args.in/main/main_wasm.mbt
+++ b/crates/moon/tests/test_cases/moon_run_with_cli_args.in/main/main_wasm.mbt
@@ -74,7 +74,7 @@ fn string_read_char(handle : StringReadHandle) -> Int = "__moonbit_fs_unstable"
 fn finish_read_string(handle : StringReadHandle) = "__moonbit_fs_unstable" "finish_read_string"
 
 pub fn string_from_extern(e : ExternString) -> String {
-  let buf = Buffer::new()
+  let buf = @buffer.new()
   let handle = begin_read_string(e)
   while true {
     let ch = string_read_char(handle)
diff --git a/crates/moonrun/tests/test_cases/test_cli_args.in/main/main.mbt b/crates/moonrun/tests/test_cases/test_cli_args.in/main/main.mbt
index b9363700..68494826 100644
--- a/crates/moonrun/tests/test_cases/test_cli_args.in/main/main.mbt
+++ b/crates/moonrun/tests/test_cases/test_cli_args.in/main/main.mbt
@@ -96,7 +96,7 @@ fn string_read_char(handle : StringReadHandle) -> Int = "__moonbit_fs_unstable"
 fn finish_read_string(handle : StringReadHandle) = "__moonbit_fs_unstable" "finish_read_string"
 
 fn string_from_extern(e : ExternString) -> String {
-  let buf = Buffer::new()
+  let buf = @buffer.new()
   let handle = begin_read_string(e)
   while true {
     let ch = string_read_char(handle)