diff --git a/Cargo.lock b/Cargo.lock
index dfc24be..5031bb6 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -153,7 +153,7 @@ checksum = "7fcaabb2fef8c910e7f4c7ce9f67a1283a1715879a7c230ca9d6d1ae31f16d91"
 [[package]]
 name = "els"
 version = "0.1.28-nightly.7"
-source = "git+https://github.com/erg-lang/erg?branch=main#3f9e70bd9db6cc2443423b0525bf72f52d7c6fcb"
+source = "git+https://github.com/erg-lang/erg?branch=main#281262b7bf7c41cbb0b738e660cea37926016780"
 dependencies = [
  "erg_common",
  "erg_compiler",
@@ -177,7 +177,7 @@ dependencies = [
 [[package]]
 name = "erg_common"
 version = "0.6.16-nightly.7"
-source = "git+https://github.com/erg-lang/erg?branch=main#3f9e70bd9db6cc2443423b0525bf72f52d7c6fcb"
+source = "git+https://github.com/erg-lang/erg?branch=main#281262b7bf7c41cbb0b738e660cea37926016780"
 dependencies = [
  "backtrace-on-stack-overflow",
  "parking_lot",
@@ -187,7 +187,7 @@ dependencies = [
 [[package]]
 name = "erg_compiler"
 version = "0.6.16-nightly.7"
-source = "git+https://github.com/erg-lang/erg?branch=main#3f9e70bd9db6cc2443423b0525bf72f52d7c6fcb"
+source = "git+https://github.com/erg-lang/erg?branch=main#281262b7bf7c41cbb0b738e660cea37926016780"
 dependencies = [
  "erg_common",
  "erg_parser",
@@ -196,7 +196,7 @@ dependencies = [
 [[package]]
 name = "erg_parser"
 version = "0.6.16-nightly.7"
-source = "git+https://github.com/erg-lang/erg?branch=main#3f9e70bd9db6cc2443423b0525bf72f52d7c6fcb"
+source = "git+https://github.com/erg-lang/erg?branch=main#281262b7bf7c41cbb0b738e660cea37926016780"
 dependencies = [
  "erg_common",
  "unicode-xid",
@@ -563,9 +563,9 @@ checksum = "5b40af805b3121feab8a3c29f04d8ad262fa8e0561883e7653e024ae4479e6de"
 
 [[package]]
 name = "proc-macro2"
-version = "1.0.63"
+version = "1.0.64"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7b368fba921b0dce7e60f5e04ec15e565b3303972b42bcfde1d0713b881959eb"
+checksum = "78803b62cbf1f46fde80d7c0e803111524b9877184cfe7c3033659490ac7a7da"
 dependencies = [
  "unicode-ident",
 ]
@@ -767,29 +767,29 @@ checksum = "bebd363326d05ec3e2f532ab7660680f3b02130d780c299bca73469d521bc0ed"
 
 [[package]]
 name = "serde"
-version = "1.0.167"
+version = "1.0.171"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7daf513456463b42aa1d94cff7e0c24d682b429f020b9afa4f5ba5c40a22b237"
+checksum = "30e27d1e4fd7659406c492fd6cfaf2066ba8773de45ca75e855590f856dc34a9"
 dependencies = [
  "serde_derive",
 ]
 
 [[package]]
 name = "serde_derive"
-version = "1.0.167"
+version = "1.0.171"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b69b106b68bc8054f0e974e70d19984040f8a5cf9215ca82626ea4853f82c4b9"
+checksum = "389894603bd18c46fa56231694f8d827779c0951a667087194cf9de94ed24682"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.23",
+ "syn 2.0.25",
 ]
 
 [[package]]
 name = "serde_json"
-version = "1.0.100"
+version = "1.0.102"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0f1e14e89be7aa4c4b78bdbdc9eb5bf8517829a600ae8eaa39a6e1d960b5185c"
+checksum = "b5062a995d481b2308b6064e9af76011f2921c35f97b0468811ed9f6cd91dfed"
 dependencies = [
  "itoa",
  "ryu",
@@ -804,7 +804,7 @@ checksum = "1d89a8107374290037607734c0b73a85db7ed80cae314b3c5791f192a496e731"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.23",
+ "syn 2.0.25",
 ]
 
 [[package]]
@@ -850,9 +850,9 @@ dependencies = [
 
 [[package]]
 name = "syn"
-version = "2.0.23"
+version = "2.0.25"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "59fb7d6d8281a51045d62b8eb3a7d1ce347b76f312af50cd3dc0af39c87c1737"
+checksum = "15e3fc8c0c74267e2df136e5e5fb656a464158aa57624053375eb9c8c6e25ae2"
 dependencies = [
  "proc-macro2",
  "quote",
diff --git a/tests/test.rs b/tests/test.rs
index cdf71ff..e8498a1 100644
--- a/tests/test.rs
+++ b/tests/test.rs
@@ -17,90 +17,104 @@ pub fn exec_analyzer(file_path: &'static str) -> Result<CompleteArtifact, Incomp
     analyzer.analyze(py_code, "exec")
 }
 
-fn _expect(file_path: &'static str, warns: usize, errors: usize) {
+fn _expect(file_path: &'static str, warns: usize, errors: usize) -> Result<(), String> {
     println!("Testing {file_path} ...");
     match exec_analyzer(file_path) {
         Ok(artifact) => {
-            assert_eq!(artifact.warns.len(), warns);
-            assert_eq!(errors, 0);
+            if artifact.warns.len() != warns {
+                return Err(format!(
+                    "Expected {warns} warnings, found {}",
+                    artifact.warns.len()
+                ));
+            }
+            if errors != 0 {
+                return Err(format!("Expected {errors} errors, found 0"));
+            }
+            Ok(())
         }
         Err(artifact) => {
-            assert_eq!(artifact.warns.len(), warns);
-            assert_eq!(artifact.errors.len(), errors);
+            if artifact.warns.len() != warns {
+                return Err(format!(
+                    "Expected {warns} warnings, found {}",
+                    artifact.warns.len()
+                ));
+            }
+            if artifact.errors.len() != errors {
+                return Err(format!(
+                    "Expected {errors} errors, found {}",
+                    artifact.errors.len()
+                ));
+            }
+            Ok(())
         }
     }
 }
 
-pub fn expect(file_path: &'static str, warns: usize, errors: usize) {
-    exec_new_thread(
-        move || {
-            _expect(file_path, warns, errors);
-        },
-        file_path,
-    );
+pub fn expect(file_path: &'static str, warns: usize, errors: usize) -> Result<(), String> {
+    exec_new_thread(move || _expect(file_path, warns, errors), file_path)
 }
 
 #[test]
-fn exec_test() {
-    expect("tests/test.py", 0, 15);
+fn exec_test() -> Result<(), String> {
+    expect("tests/test.py", 0, 15)
 }
 
 #[test]
-fn exec_import() {
-    expect("tests/import.py", 1, 2);
+fn exec_import() -> Result<(), String> {
+    expect("tests/import.py", 1, 2)
 }
 
 #[test]
-fn exec_export() {
-    expect("tests/export.py", 0, 0);
+fn exec_export() -> Result<(), String> {
+    expect("tests/export.py", 0, 0)
 }
 
 #[test]
-fn exec_func() {
-    expect("tests/func.py", 0, 1);
+fn exec_func() -> Result<(), String> {
+    expect("tests/func.py", 0, 1)
 }
 
 #[test]
-fn exec_class() {
-    expect("tests/class.py", 0, 4);
+fn exec_class() -> Result<(), String> {
+    expect("tests/class.py", 0, 4)
 }
 
 #[test]
-fn exec_errors() {
-    expect("tests/errors.py", 0, 3);
+fn exec_errors() -> Result<(), String> {
+    expect("tests/errors.py", 0, 3)
 }
 
 #[test]
-fn exec_warns() {
-    expect("tests/warns.py", 2, 0);
+fn exec_warns() -> Result<(), String> {
+    expect("tests/warns.py", 2, 0)
 }
 
 #[test]
-fn exec_typespec() {
-    expect("tests/typespec.py", 0, 7);
+fn exec_typespec() -> Result<(), String> {
+    expect("tests/typespec.py", 0, 7)
 }
 
 #[test]
-fn exec_projection() {
-    expect("tests/projection.py", 0, 4);
+fn exec_projection() -> Result<(), String> {
+    expect("tests/projection.py", 0, 4)
 }
 
 #[test]
-fn exec_narrowing() {
-    expect("tests/narrowing.py", 0, 1);
+fn exec_narrowing() -> Result<(), String> {
+    expect("tests/narrowing.py", 0, 1)
 }
 
 #[test]
-fn exec_casting() {
-    expect("tests/casting.py", 1, 1);
+fn exec_casting() -> Result<(), String> {
+    expect("tests/casting.py", 1, 1)
 }
 
 #[test]
-fn exec_collections() {
-    expect("tests/collections.py", 0, 4);
+fn exec_collections() -> Result<(), String> {
+    expect("tests/collections.py", 0, 4)
 }
 
 #[test]
-fn exec_call() {
-    expect("tests/call.py", 0, 3);
+fn exec_call() -> Result<(), String> {
+    expect("tests/call.py", 0, 3)
 }