util: uart_stress_tester raises an error on character loss

This patch let the tester exit with an error code on test failure.
It would make easy the future autotest to detect a failure.

BUG=None
BRANCH=None
TEST=ran on fleex.

$ uart_stress_tester.py /dev/ttyUSB1 /dev/ttyUSB2 -t 120 -d

[before patch]
...
INFO   | UartSerial| EC |    14888 char lost /    1382400 (1.1 %)
INFO   | UartSerial| AP |        0 char lost /    1382400 (0.0 %)
ERROR  | ChargenTest    | FAIL: lost 14888 character(s) from the test
...
$ echo $?
0

[after patch]
...
INFO   | UartSerial| EC |    14888 char lost /    1382400 (1.1 %)
INFO   | UartSerial| AP |        0 char lost /    1382400 (0.0 %)
ERROR  | ChargenTest    | FAIL: lost 14888 character(s) from the test
Error:  Test failed for losing 144888 character(s)
...
$ echo $?
1

$ ./util/uart_stress_tester.py /dev/ttyUSB1 /dev/ttyUSB2 -t 120 -d
Error:  /dev/ttyUSB1 does not exist.
$ echo $?
1

Change-Id: I210efd4ad7fdb8eb612206624eda6c39c5bb3b1c
Signed-off-by: Namyoon Woo <namyoon@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/1696115
Reviewed-by: Vadim Bendebury <vbendeb@chromium.org>
Reviewed-by: Aseda Aboagye <aaboagye@chromium.org>

1 files changed, 27 insertions, 8 deletions

diff --git a/util/uart_stress_tester.py b/util/uart_stress_tester.py
index 13828fe84e..e2f9f278fe 100755
--- a/util/uart_stress_tester.py
+++ b/util/uart_stress_tester.py
@@ -251,7 +251,11 @@ class UartSerial(object):
       self.serial.close()
 
   def stress_test_thread(self):
-    """Test thread"""
+    """Test thread
+
+    Raises:
+      ChargenTestError: if broken character is found.
+    """
     try:
       self.serial.open()
       self.serial.flushInput()
@@ -295,9 +299,11 @@ class UartSerial(object):
             # If it is not alpha-numeric, terminate the test.
             if ch_cap not in CRLF:
               # If it is neither a CR nor LF, then it is an error case.
-              self.logger.error(err_msg, 'Broken char captured',
-                                ch_exp, hex(ord(ch_cap)), self.num_ch_cap)
               self.logger.error('Whole captured characters: %r', captured)
+              raise ChargenTestError(err_msg % ('Broken char captured', ch_exp,
+                                                hex(ord(ch_cap)),
+                                                self.num_ch_cap))
+
             # Set the loop termination condition true.
             total_num_ch = self.num_ch_cap
 
@@ -421,7 +427,11 @@ class ChargenTest(object):
     self.logger.info('Ports are ready to test')
 
   def print_result(self):
-    """Display the test result for each UART port"""
+    """Display the test result for each UART port
+
+    Returns:
+      char_lost: Total number of characters lost
+    """
     char_lost = 0
     for _, ser in self.serials.items():
       (tmp_lost, _, _) = ser.get_result()
@@ -434,8 +444,14 @@ class ChargenTest(object):
     else:
       self.logger.info('PASS: %s', msg)
 
+    return char_lost
+
   def run(self):
-    """Run the stress test on UART port(s)"""
+    """Run the stress test on UART port(s)
+
+    Raises:
+      ChargenTestError: If any characters are lost.
+    """
 
     # Detect UART source type, and decide which command to test.
     self.prepare()
@@ -450,9 +466,12 @@ class ChargenTest(object):
       ser.wait_test_done()
 
     # Print the result.
-    self.print_result()
-    self.logger.info('Test is done')
+    char_lost = self.print_result()
+    if char_lost:
+      raise ChargenTestError('Test failed: lost %d character(s)' %
+                             char_lost)
 
+    self.logger.info('Test is done')
 
 def parse_args(cmdline):
   """Parse command line arguments.
@@ -514,7 +533,7 @@ def main():
     sys.exit(0)
 
   except ChargenTestError as e:
-    print('Error: ', str(e))
+    logging.error(str(e))
     sys.exit(1)
 
 if __name__ == '__main__':