simplify test

Author: Michiel de Hoon

Lib/test/test_tkinter/test_vwait_busyloop_stdin.py

@@ -10,6 +10,7 @@
 
 
 @unittest.skipUnless(support.has_subprocess_support, "test requires subprocess")
+@unittest.skipIf(sys.platform == "win32", "test not supported on Windows")
 class TkVwaitMainloopStdinTest(unittest.TestCase):
 
     def run_child(self):
@@ -27,15 +28,11 @@ def do_vwait():
     end_cpu = time.process_time()
     end_wall = time.time()
     cpu_frac = (end_cpu - start_cpu) / (end_wall - start_wall)
-    print(f"CPU fraction during vwait: {cpu_frac:.2f}", flush=True)
+    print(cpu_frac)
 
 # Schedule vwait and release
 interp.after(100, do_vwait)
 interp.after(500, lambda: interp.setvar("myvar", "done"))
-# Schedule quit to stop mainloop
-interp.after(1000, interp.quit)
-
-interp.mainloop()
 """
 
         # Start child in interactive mode, but use -c to execute code immediately
@@ -54,12 +51,10 @@ def test_vwait_stdin_busy_loop(self):
         time.sleep(0.15)
 
         # Send input to stdin to trigger the bug
-        proc.stdin.write(b"x\n")
-        proc.stdin.flush()
+        proc.stdin.write(b"\n")
 
         # Ensure child exits cleanly
         proc.stdin.write(b"exit()\n")
-        proc.stdin.flush()
 
         stdout, stderr = proc.communicate()
         out = stdout.decode("utf-8", errors="replace")
@@ -69,13 +64,7 @@ def test_vwait_stdin_busy_loop(self):
             self.fail(f"Child exited with {proc.returncode}\nSTDOUT:\n{out}\nSTDERR:\n{err}")
 
         # Extract CPU fraction printed by child
-        cpu_frac = None
-        for line in out.splitlines():
-            if line.startswith("CPU fraction during vwait:"):
-                cpu_frac = float(line.split(":")[1].strip())
-                break
-
-        self.assertIsNotNone(cpu_frac, "CPU fraction not printed by child")
+        cpu_frac = float(out)
 
         # Fail if CPU fraction is too high (indicative of busy-loop)
         self.assertLess(cpu_frac, 0.5,