diff --git a/crates/moon/tests/mod.rs b/crates/moon/tests/mod.rs
index e05cc6c5..200bd233 100644
--- a/crates/moon/tests/mod.rs
+++ b/crates/moon/tests/mod.rs
@@ -82,6 +82,25 @@ pub fn get_stdout_with_args_without_replace(
     s
 }
 
+#[track_caller]
+pub fn get_stderr_on_success_with_args_without_replace(
+    dir: &impl AsRef<std::path::Path>,
+    args: impl IntoIterator<Item = impl AsRef<std::ffi::OsStr>>,
+) -> String {
+    let out = snapbox::cmd::Command::new(moon_bin())
+        .current_dir(dir)
+        .args(args)
+        .assert()
+        .success()
+        .get_output()
+        .stderr
+        .to_owned();
+
+    let s = std::str::from_utf8(&out).unwrap().to_string();
+    s
+}
+
+#[track_caller]
 pub fn get_stderr_with_args_without_replace(
     dir: &impl AsRef<std::path::Path>,
     args: impl IntoIterator<Item = impl AsRef<std::ffi::OsStr>>,
@@ -149,6 +168,14 @@ pub fn get_stderr_with_args_and_replace_dir(
 }
 
 #[track_caller]
+pub fn get_stderr_on_success_with_args_and_replace_dir(
+    dir: &impl AsRef<std::path::Path>,
+    args: impl IntoIterator<Item = impl AsRef<std::ffi::OsStr>>,
+) -> String {
+    let s = get_stderr_on_success_with_args_without_replace(dir, args);
+    replace_dir(&s, dir)
+}
+
 pub fn get_stderr_with_args(
     dir: &impl AsRef<std::path::Path>,
     args: impl IntoIterator<Item = impl AsRef<std::ffi::OsStr>>,
@@ -168,6 +195,25 @@ pub fn get_stderr_with_args(
     s.replace('\\', "/")
 }
 
+pub fn get_stderr_on_success_with_args(
+    dir: &impl AsRef<std::path::Path>,
+    args: impl IntoIterator<Item = impl AsRef<std::ffi::OsStr>>,
+) -> String {
+    let out = snapbox::cmd::Command::new(moon_bin())
+        .current_dir(dir)
+        .args(args)
+        .assert()
+        .success()
+        .get_output()
+        .stderr
+        .to_owned();
+
+    let s = std::str::from_utf8(&out).unwrap().to_string();
+    let s = s.replace("\r\n", "\n");
+
+    s.replace('\\', "/")
+}
+
 pub fn copy(src: &Path, dest: &Path) -> anyhow::Result<()> {
     if src.is_dir() {
         if !dest.exists() {
diff --git a/crates/moon/tests/test_cases/mod.rs b/crates/moon/tests/test_cases/mod.rs
index 6c30d1e8..fe9aacca 100644
--- a/crates/moon/tests/test_cases/mod.rs
+++ b/crates/moon/tests/test_cases/mod.rs
@@ -1544,13 +1544,6 @@ fn test_moon_test_succ() {
             ["test", "-v", "--sort-input", "--no-parallelize"],
         ),
         expect![[r#"
-            Warning: [1001]
-               ╭─[$ROOT/lib2/nested/lib.mbt:1:4]
-               │
-             1 │ fn add1(x : Int) -> Int {
-               │    ──┬─  
-               │      ╰─── Warning: Unused function 'add1'
-            ───╯
             test moontest/lib/hello_wbtest.mbt::0 ok
             test moontest/lib2/hello_wbtest.mbt::0 ok
             test moontest/lib2/nested/lib_wbtest.mbt::0 ok
@@ -3259,7 +3252,10 @@ fn test_warn_list_real_run() {
     let dir = TestDir::new("warn_list.in");
 
     check(
-        &get_stdout_with_args_and_replace_dir(&dir, ["build", "--sort-input", "--no-render"]),
+        &get_stderr_on_success_with_args_and_replace_dir(
+            &dir,
+            ["build", "--sort-input", "--no-render"],
+        ),
         expect![[r#"
             Finished. moon: ran 4 tasks, now up to date
         "#]],
@@ -3273,7 +3269,10 @@ fn test_warn_list_real_run() {
     );
 
     check(
-        &get_stdout_with_args_and_replace_dir(&dir, ["bundle", "--sort-input", "--no-render"]),
+        &get_stderr_on_success_with_args_and_replace_dir(
+            &dir,
+            ["bundle", "--sort-input", "--no-render"],
+        ),
         expect![[r#"
             Finished. moon: ran 4 tasks, now up to date
         "#]],
@@ -3283,7 +3282,10 @@ fn test_warn_list_real_run() {
     get_stdout_with_args_and_replace_dir(&dir, ["bundle", "--sort-input"]);
 
     check(
-        &get_stdout_with_args_and_replace_dir(&dir, ["check", "--sort-input", "--no-render"]),
+        &get_stderr_on_success_with_args_and_replace_dir(
+            &dir,
+            ["check", "--sort-input", "--no-render"],
+        ),
         expect![[r#"
             Finished. moon: ran 3 tasks, now up to date
         "#]],
@@ -3296,7 +3298,7 @@ fn test_alert_list() {
     let dir = TestDir::new("alert_list.in");
 
     check(
-        &get_stdout_with_args_and_replace_dir(&dir, ["build", "--sort-input"]),
+        &get_stderr_on_success_with_args_and_replace_dir(&dir, ["build", "--sort-input"]),
         expect![[r#"
             Warning: [2000]
                ╭─[$ROOT/main/main.mbt:3:3]
@@ -3317,7 +3319,7 @@ fn test_alert_list() {
     );
 
     check(
-        &get_stdout_with_args_and_replace_dir(&dir, ["bundle", "--sort-input"]),
+        &get_stderr_on_success_with_args_and_replace_dir(&dir, ["bundle", "--sort-input"]),
         expect![[r#"
             Warning: [2000]
                ╭─[$ROOT/main/main.mbt:3:3]
@@ -3331,7 +3333,7 @@ fn test_alert_list() {
     );
 
     check(
-        &get_stdout_with_args_and_replace_dir(&dir, ["check", "--sort-input"]),
+        &get_stderr_on_success_with_args_and_replace_dir(&dir, ["check", "--sort-input"]),
         expect![[r#"
             Warning: [2000]
                ╭─[$ROOT/main/main.mbt:3:3]
@@ -3361,15 +3363,15 @@ fn test_mod_level_warn_alert_list() {
 #[test]
 fn test_no_work_to_do() {
     let dir = TestDir::new("moon_new.in");
-    let out = get_stdout_with_args_and_replace_dir(&dir, ["check"]);
+    let out = get_stderr_on_success_with_args_and_replace_dir(&dir, ["check"]);
     assert!(out.contains("now up to date"));
 
-    let out = get_stdout_with_args_and_replace_dir(&dir, ["check"]);
+    let out = get_stderr_on_success_with_args_and_replace_dir(&dir, ["check"]);
     assert!(out.contains("moon: no work to do"));
 
-    let out = get_stdout_with_args_and_replace_dir(&dir, ["build"]);
+    let out = get_stderr_on_success_with_args_and_replace_dir(&dir, ["build"]);
     assert!(out.contains("now up to date"));
-    let out = get_stdout_with_args_and_replace_dir(&dir, ["build"]);
+    let out = get_stderr_on_success_with_args_and_replace_dir(&dir, ["build"]);
     assert!(out.contains("moon: no work to do"));
 }
 
@@ -3437,7 +3439,7 @@ fn test_deny_warn() {
     let dir = TestDir::new("test_deny_warn.in");
 
     check(
-        &get_stdout_with_args_and_replace_dir(&dir, ["check", "--sort-input"]),
+        &get_stderr_on_success_with_args_and_replace_dir(&dir, ["check", "--sort-input"]),
         expect![[r#"
             Warning: [2000]
                 ╭─[$ROOT/lib/hello.mbt:14:3]
@@ -3501,7 +3503,7 @@ fn test_deny_warn() {
     ));
 
     check(
-        &get_stdout_with_args_and_replace_dir(&dir, ["build", "--sort-input"]),
+        &get_stderr_on_success_with_args_and_replace_dir(&dir, ["build", "--sort-input"]),
         expect![[r#"
             Warning: [2000]
                 ╭─[$ROOT/lib/hello.mbt:14:3]
@@ -3858,7 +3860,7 @@ fn test_multi_process() {
 
                 if output.status.success() {
                     success.fetch_add(1, std::sync::atomic::Ordering::SeqCst);
-                    let out = String::from_utf8(output.stdout).unwrap();
+                    let out = String::from_utf8(output.stderr).unwrap();
                     assert!(out.contains("no work to do") || out.contains("now up to date"));
                 } else {
                     println!("moon output: {:?}", String::from_utf8(output.stdout));
@@ -4148,7 +4150,7 @@ fn whitespace_test() {
         "#]],
     );
 
-    let out = get_stdout_with_args(&dir, ["check"]);
+    let out = get_stderr_on_success_with_args(&dir, ["check"]);
     assert!(out.contains("moon: ran 3 tasks, now up to date"));
 }
 
@@ -4188,7 +4190,7 @@ fn test_whitespace_parent_space() -> anyhow::Result<()> {
         "#]],
     );
 
-    let out = get_stdout_with_args(&path_with_space, ["build", "--no-render"]);
+    let out = get_stderr_on_success_with_args(&path_with_space, ["build", "--no-render"]);
     let out = out.replace(&prefix, ".");
     let out = out.replace(
         &moonutil::moon_dir::home()
@@ -4202,8 +4204,8 @@ fn test_whitespace_parent_space() -> anyhow::Result<()> {
     check(
         &out,
         expect![[r#"
-            Finished. moon: ran 3 tasks, now up to date
-        "#]],
+        Finished. moon: ran 3 tasks, now up to date
+    "#]],
     );
     Ok(())
 }
@@ -4358,7 +4360,7 @@ fn test_render_no_location() {
         .assert()
         .failure()
         .get_output()
-        .stdout
+        .stderr
         .to_owned();
 
     let output = String::from_utf8_lossy(&output);
@@ -4420,7 +4422,7 @@ fn test_third_party() {
     get_stdout_with_args_and_replace_dir(&dir, ["build"]);
     get_stdout_with_args_and_replace_dir(&dir, ["clean"]);
 
-    let actual = &get_stdout_with_args_and_replace_dir(&dir, ["check"]);
+    let actual = &get_stderr_on_success_with_args_and_replace_dir(&dir, ["check"]);
     assert!(actual.contains("moon: ran 4 tasks, now up to date"));
 
     check(
@@ -4442,7 +4444,7 @@ fn test_third_party() {
         "#]],
     );
 
-    let actual = &get_stdout_with_args_and_replace_dir(&dir, ["build"]);
+    let actual = &get_stderr_on_success_with_args_and_replace_dir(&dir, ["build"]);
     assert!(actual.contains("moon: ran 5 tasks, now up to date"));
 
     let actual = &get_stdout_with_args_and_replace_dir(&dir, ["run", "main"]);
@@ -4663,7 +4665,7 @@ fn test_blackbox_failed() {
         .assert()
         .failure()
         .get_output()
-        .stdout
+        .stderr
         .to_owned();
 
     let output = String::from_utf8_lossy(&output);
@@ -4678,7 +4680,7 @@ fn test_blackbox_failed() {
         .assert()
         .failure()
         .get_output()
-        .stdout
+        .stderr
         .to_owned();
 
     let output = String::from_utf8_lossy(&output);
@@ -5278,11 +5280,17 @@ fn test_moon_check_json_output() {
         "#]],
         );
         check(
-            &get_stdout_with_args_and_replace_dir(&dir, ["check", "--output-json"]),
+            &get_stderr_on_success_with_args_and_replace_dir(
+                &dir,
+                ["check", "--output-json", "-q"],
+            ),
+            expect![""],
+        );
+        check(
+            &get_stderr_on_success_with_args_and_replace_dir(&dir, ["check", "--output-json"]),
             expect![[r#"
-            {"$message_type":"diagnostic","level":"warning","loc":{"path":"$ROOT/main/main.mbt","start":{"line":3,"col":3,"offset":25},"end":{"line":3,"col":10,"offset":32}},"message":"Warning (Alert alert_2): alert_2","error_code":2000}
-            Finished. moon: no work to do
-        "#]],
+                Finished. moon: no work to do
+            "#]],
         );
     }
 
@@ -5296,11 +5304,17 @@ fn test_moon_check_json_output() {
         "#]],
         );
         check(
-            &get_stdout_with_args_and_replace_dir(&dir, ["check", "--output-json"]),
+            &get_stderr_on_success_with_args_and_replace_dir(
+                &dir,
+                ["check", "--output-json", "-q"],
+            ),
+            expect![""],
+        );
+        check(
+            &get_stderr_on_success_with_args_and_replace_dir(&dir, ["check", "--output-json"]),
             expect![[r#"
-            {"$message_type":"diagnostic","level":"warning","loc":{"path":"$ROOT/main/main.mbt","start":{"line":3,"col":3,"offset":27},"end":{"line":3,"col":10,"offset":34}},"message":"Warning (Alert alert_2): alert_2","error_code":2000}
-            Finished. moon: no work to do
-        "#]],
+                Finished. moon: no work to do
+            "#]],
         );
     }
 }
@@ -5417,7 +5431,7 @@ fn test_specify_source_dir_001() {
         "#]],
     );
     check(
-        &get_stdout_with_args_and_replace_dir(&dir, ["check"]),
+        &get_stderr_on_success_with_args_and_replace_dir(&dir, ["check"]),
         expect![[r#"
             Finished. moon: ran 3 tasks, now up to date
         "#]],
@@ -5477,7 +5491,7 @@ fn test_specify_source_dir_001() {
         )
     }
     check(
-        &get_stdout_with_args_and_replace_dir(&dir, ["build"]),
+        &get_stderr_on_success_with_args_and_replace_dir(&dir, ["build"]),
         expect![[r#"
             Finished. moon: ran 3 tasks, now up to date
         "#]],
@@ -5553,7 +5567,7 @@ fn test_specify_source_dir_003() {
 fn test_specify_source_dir_004() {
     let dir = TestDir::new("specify_source_dir_004.in");
     check(
-        &get_stdout_with_args_and_replace_dir(&dir, ["check"]),
+        &get_stderr_on_success_with_args_and_replace_dir(&dir, ["check"]),
         expect![[r#"
             Finished. moon: ran 3 tasks, now up to date
         "#]],
@@ -5618,13 +5632,13 @@ fn test_specify_source_dir_with_deps() {
         "#]],
     );
     check(
-        &get_stdout_with_args_and_replace_dir(&dir, ["check"]),
+        &get_stderr_on_success_with_args_and_replace_dir(&dir, ["check"]),
         expect![[r#"
             Finished. moon: ran 6 tasks, now up to date
         "#]],
     );
     check(
-        &get_stdout_with_args_and_replace_dir(&dir, ["build"]),
+        &get_stderr_on_success_with_args_and_replace_dir(&dir, ["build"]),
         expect![[r#"
             Finished. moon: ran 5 tasks, now up to date
         "#]],
@@ -5649,13 +5663,13 @@ fn test_specify_source_dir_with_deps() {
 fn test_specify_source_dir_with_deps_002() {
     let dir = TestDir::new("specify_source_dir_with_deps_002.in");
     check(
-        &get_stdout_with_args_and_replace_dir(&dir, ["check"]),
+        &get_stderr_on_success_with_args_and_replace_dir(&dir, ["check"]),
         expect![[r#"
             Finished. moon: ran 13 tasks, now up to date
         "#]],
     );
     check(
-        &get_stdout_with_args_and_replace_dir(&dir, ["build"]),
+        &get_stderr_on_success_with_args_and_replace_dir(&dir, ["build"]),
         expect![[r#"
             Finished. moon: ran 10 tasks, now up to date
         "#]],
diff --git a/crates/moon/tests/test_cases/moon_info_001.in/moon.test b/crates/moon/tests/test_cases/moon_info_001.in/moon.test
index 45a9724a..6711b899 100644
--- a/crates/moon/tests/test_cases/moon_info_001.in/moon.test
+++ b/crates/moon/tests/test_cases/moon_info_001.in/moon.test
@@ -1,4 +1,5 @@
   $ moon info
+  
   Finished. moon: ran 2 tasks, now up to date
   
   $ xcat src/lib/lib.mbti
diff --git a/crates/moon/tests/test_cases/moon_info_002.in/moon.test b/crates/moon/tests/test_cases/moon_info_002.in/moon.test
index c87400f4..15e88f8f 100644
--- a/crates/moon/tests/test_cases/moon_info_002.in/moon.test
+++ b/crates/moon/tests/test_cases/moon_info_002.in/moon.test
@@ -1,4 +1,5 @@
   $ moon info
+  
   Finished. moon: ran 1 task, now up to date
   
   $ xcat lib/lib.mbti
diff --git a/crates/moon/tests/test_cases/specify_source_dir_001.in/moon.test b/crates/moon/tests/test_cases/specify_source_dir_001.in/moon.test
index c9669c10..395033a4 100644
--- a/crates/moon/tests/test_cases/specify_source_dir_001.in/moon.test
+++ b/crates/moon/tests/test_cases/specify_source_dir_001.in/moon.test
@@ -18,6 +18,7 @@
   moonc link-core $MOON_HOME/lib/core/target/wasm-gc/release/bundle/core.core ./target/wasm-gc/debug/test/lib/lib.internal_test.core -main username/hello/lib -o ./target/wasm-gc/debug/test/lib/lib.internal_test.wasm -test-mode -pkg-sources username/hello/lib:./src/lib -pkg-sources moonbitlang/core:$MOON_HOME/lib/core -target wasm-gc -g
   
   $ moon check
+  
   Finished. moon: ran 3 tasks, now up to date
   
   $ xcat target/wasm-gc/release/check/packages.json
@@ -68,6 +69,7 @@
     "source": "src"
   }
   $ moon build
+  
   Finished. moon: ran 3 tasks, now up to date
   
   $ moon test
diff --git a/crates/moon/tests/test_cases/test_moon_info.in/moon.test b/crates/moon/tests/test_cases/test_moon_info.in/moon.test
index 09bffc3e..80783d2d 100644
--- a/crates/moon/tests/test_cases/test_moon_info.in/moon.test
+++ b/crates/moon/tests/test_cases/test_moon_info.in/moon.test
@@ -1,6 +1,7 @@
   $ xls lib
   lib.mbt moon.pkg.json
   $ moon info
+  
   Finished. moon: ran 1 task, now up to date
   
   $ xls lib
diff --git a/crates/moonbuild/src/entry.rs b/crates/moonbuild/src/entry.rs
index 0fb5cef8..8ab8b7c3 100644
--- a/crates/moonbuild/src/entry.rs
+++ b/crates/moonbuild/src/entry.rs
@@ -61,13 +61,13 @@ fn render_result(result: Option<usize>, quiet: bool, mode: &str) -> anyhow::Resu
         Some(0) => {
             // Special case: don't print numbers when no work done.
             if !quiet {
-                println!("{} moon: no work to do", "Finished.".bright_green().bold());
+                eprintln!("{} moon: no work to do", "Finished.".bright_green().bold());
             }
             Ok(0)
         }
         Some(n) => {
             if !quiet {
-                println!(
+                eprintln!(
                     "{} moon: ran {} task{}, now up to date",
                     "Finished.".bright_green().bold(),
                     n,
diff --git a/crates/moonutil/src/render.rs b/crates/moonutil/src/render.rs
index b5e4e624..abcf796c 100644
--- a/crates/moonutil/src/render.rs
+++ b/crates/moonutil/src/render.rs
@@ -50,7 +50,7 @@ impl MooncDiagnostic {
 
                 // for no-location diagnostic, like Missing main function in the main package(4067)
                 if diagnostic.location.path.is_empty() {
-                    println!(
+                    eprintln!(
                         "{}",
                         format!(
                             "[{}] {}: {}",
@@ -63,7 +63,7 @@ impl MooncDiagnostic {
                     let source_file = match std::fs::read_to_string(source_file_path) {
                         Ok(content) => content,
                         Err(_) => {
-                            println!(
+                            eprintln!(
                                 "failed to read file `{}`, [{}] {}: {}",
                                 source_file_path,
                                 diagnostic.error_code,
@@ -97,12 +97,12 @@ impl MooncDiagnostic {
 
                     report_builder
                         .finish()
-                        .print((source_file_path, ariadne::Source::from(source_file)))
+                        .eprint((source_file_path, ariadne::Source::from(source_file)))
                         .unwrap();
                 }
             }
             Err(_) => {
-                println!("{}", content);
+                eprintln!("{}", content);
             }
         }
     }