diff --git a/tests/test_multiprocess.py b/tests/test_multiprocess.py
index dfb8ce14..543344f8 100644
--- a/tests/test_multiprocess.py
+++ b/tests/test_multiprocess.py
@@ -45,6 +45,12 @@ def fib(n):
 print(subprocess.call(["python", "-m", "timeit", "-n", "100", "'1+1'"]))
 """
 
+file_subprocess_code_string = """
+import subprocess
+p = subprocess.Popen(['python', '-c', 'import time;time.sleep(0.5)'])
+p.wait()
+"""
+
 file_fork = """
 import os
 import time
@@ -227,6 +233,13 @@ def setUp(self):
     def tearDown(self):
         os.remove("child.py")
 
+    def assertSubprocessName(self, name, data):
+        for entry in data["traceEvents"]:
+            if entry["name"] == "process_name" and entry["args"]["name"] == name:
+                break
+        else:
+            self.fail("no matching subprocess name")
+
     def test_basic(self):
         def check_func(data):
             pids = set()
@@ -242,13 +255,7 @@ def test_child_process(self):
                           expected_output_file=None)
             self.assertEqual(len(os.listdir(tmpdir)), 1)
             with open(os.path.join(tmpdir, os.listdir(tmpdir)[0])) as f:
-                trace_events = json.load(f)["traceEvents"]
-                for entry in trace_events:
-                    if entry["name"] == "process_name":
-                        self.assertNotEqual(entry["args"]["name"], "MainProcess")
-                        break
-                else:
-                    self.fail("no process_name event found")
+                self.assertSubprocessName("child.py", json.load(f))
 
     def test_module(self):
         with tempfile.TemporaryDirectory() as tmpdir:
@@ -256,28 +263,23 @@ def test_module(self):
             self.template(["viztracer", "-o", output_file, "cmdline_test.py"],
                           expected_output_file=output_file,
                           expected_stdout=".*100 loops.*",
-                          script=file_subprocess_module, cleanup=False)
-            with open(output_file) as f:
-                trace_events = json.load(f)["traceEvents"]
-                for entry in trace_events:
-                    if entry["name"] == "process_name" and entry["args"]["name"] == "timeit":
-                        break
-                else:
-                    self.fail("no valid child process_name event found")
-
-    def test_code(self):
+                          script=file_subprocess_module,
+                          check_func=lambda data: self.assertSubprocessName("timeit", data))
+
+    def test_code_string(self):
         with tempfile.TemporaryDirectory() as tmpdir:
+            output_path = os.path.join(tmpdir, "result.json")
+            self.template(["viztracer", "-o", output_path, "cmdline_test.py"],
+                          expected_output_file=output_path,
+                          script=file_subprocess_code_string,
+                          check_func=lambda data: self.assertSubprocessName("python -c", data))
+
+            # this is for coverage
             self.template(['viztracer', '-o', os.path.join(tmpdir, "result.json"), '--subprocess_child',
                            '-c', 'import time;time.sleep(0.5)'], expected_output_file=None)
             self.assertEqual(len(os.listdir(tmpdir)), 1)
             with open(os.path.join(tmpdir, os.listdir(tmpdir)[0])) as f:
-                trace_events = json.load(f)["traceEvents"]
-                for entry in trace_events:
-                    if entry["name"] == "process_name":
-                        self.assertEqual(entry["args"]["name"], "python -c")
-                        break
-                else:
-                    self.fail("no valid child process_name event found")
+                self.assertSubprocessName("python -c", json.load(f))
 
     def test_nested(self):
         def check_func(data):