improve slcanTestCase robustness (#1559)

Author: zariiii9003

test/test_slcan.py

@@ -1,6 +1,9 @@
 #!/usr/bin/env python
 
 import unittest
+from typing import cast
+
+import serial
 
 import can
 
@@ -15,16 +18,17 @@
 
 https://realpython.com/pypy-faster-python/#it-doesnt-work-well-with-c-extensions
 """
-TIMEOUT = 0.5 if IS_PYPY else 0.001  # 0.001 is the default set in slcanBus
+TIMEOUT = 0.5 if IS_PYPY else 0.01  # 0.001 is the default set in slcanBus
 
 
 class slcanTestCase(unittest.TestCase):
     def setUp(self):
-        self.bus = can.Bus(
-            "loop://", interface="slcan", sleep_after_open=0, timeout=TIMEOUT
+        self.bus = cast(
+            can.interfaces.slcan.slcanBus,
+            can.Bus("loop://", interface="slcan", sleep_after_open=0, timeout=TIMEOUT),
         )
-        self.serial = self.bus.serialPortOrig
-        self.serial.read(self.serial.in_waiting)
+        self.serial = cast(serial.Serial, self.bus.serialPortOrig)
+        self.serial.reset_input_buffer()
 
     def tearDown(self):
         self.bus.shutdown()
@@ -44,8 +48,9 @@ def test_send_extended(self):
             arbitration_id=0x12ABCDEF, is_extended_id=True, data=[0xAA, 0x55]
         )
         self.bus.send(msg)
-        data = self.serial.read(self.serial.in_waiting)
-        self.assertEqual(data, b"T12ABCDEF2AA55\r")
+        expected = b"T12ABCDEF2AA55\r"
+        data = self.serial.read(len(expected))
+        self.assertEqual(data, expected)
 
     def test_recv_standard(self):
         self.serial.write(b"t4563112233\r")
@@ -62,8 +67,9 @@ def test_send_standard(self):
             arbitration_id=0x456, is_extended_id=False, data=[0x11, 0x22, 0x33]
         )
         self.bus.send(msg)
-        data = self.serial.read(self.serial.in_waiting)
-        self.assertEqual(data, b"t4563112233\r")
+        expected = b"t4563112233\r"
+        data = self.serial.read(len(expected))
+        self.assertEqual(data, expected)
 
     def test_recv_standard_remote(self):
         self.serial.write(b"r1238\r")
@@ -79,8 +85,9 @@ def test_send_standard_remote(self):
             arbitration_id=0x123, is_extended_id=False, is_remote_frame=True, dlc=8
         )
         self.bus.send(msg)
-        data = self.serial.read(self.serial.in_waiting)
-        self.assertEqual(data, b"r1238\r")
+        expected = b"r1238\r"
+        data = self.serial.read(len(expected))
+        self.assertEqual(data, expected)
 
     def test_recv_extended_remote(self):
         self.serial.write(b"R12ABCDEF6\r")
@@ -96,8 +103,9 @@ def test_send_extended_remote(self):
             arbitration_id=0x12ABCDEF, is_extended_id=True, is_remote_frame=True, dlc=6
         )
         self.bus.send(msg)
-        data = self.serial.read(self.serial.in_waiting)
-        self.assertEqual(data, b"R12ABCDEF6\r")
+        expected = b"R12ABCDEF6\r"
+        data = self.serial.read(len(expected))
+        self.assertEqual(data, expected)
 
     def test_partial_recv(self):
         self.serial.write(b"T12ABCDEF")