htrun: serial: Use provided serial port when given

In order to work well with boards via the pyocd copy method, we should
not attempt to list Mbed style boards to see if the serial port changed
names. We should instead use the serial port as provided on the command
line. If we attempt to list Mbed style boards, we will run into an error
when the board is not Mbed-style, even if the command-line provided
serial port is correct. To add insult to injury, the error message given
in such cases gives advice that is impossible to follow; the output from
htrun recommends you provide the -u option, but you cannot; the -u
option is for mbed-ls, not htrun.

    $ mbedhtrun -f build/test.elf -p /dev/ttyUSB1:115200 -r pyocd -c pyocd --target-id 0240
    [1627903348.60][mbedls.lstools_base]MBED with target id '0240000034544e45001e00048e3800515a91000097969900' is connected, but not mounted. Use the '-u' flag to include it in the list.

The reason we are not simply overriding the pyocd plugin's
check_serial_port_ready() method is because we don't want to attempt
auto-detection of the serial port for any type of device, not just those
we'd use pyocd with. We always want to use the provided serial port when
passed in. If users want auto-detection of the serial port to use, they
can avoid providing the port on the command line to get the previous
behavior.

Fixes #267

Author: Patater

src/mbed_os_tools/test/host_tests_conn_proxy/conn_primitive_serial.py

@@ -37,13 +37,25 @@ def __init__(self, name, port, baudrate, config):
         self.skip_reset = config.get('skip_reset', False)
         self.serial = None
 
-        # Check if serial port for given target_id changed
-        # If it does we will use new port to open connections and make sure reset plugin
-        # later can reuse opened already serial port
-        #
-        # Note: This listener opens serial port and keeps connection so reset plugin uses
-        # serial port object not serial port name!
-        serial_port = HostTestPluginBase().check_serial_port_ready(self.port, target_id=self.target_id, timeout=self.polling_timeout)
+        # Assume the provided serial port is good. Don't attempt to use the
+        # target_id to re-discover the serial port, as the board may not be a
+        # fully valid DAPLink-compatable or Mbed Enabled board (it may be
+        # missing a mount point). Do not attempt to check if the serial port
+        # for given target_id changed. We will attempt to open the port and
+        # pass the already opened port object (not name) to the reset plugin.
+        serial_port = None
+        if self.port is not None:
+            # A serial port was provided.
+            # Don't pass in the target_id, so that no change in serial port via
+            # auto-discovery happens.
+            self.logger.prn_inf("using specified port '%s'" % (self.port))
+            serial_port = HostTestPluginBase().check_serial_port_ready(self.port, target_id=None, timeout=self.polling_timeout)
+        else:
+            # No serial port was provided.
+            # Fallback to auto-discovery via target_id.
+            self.logger.prn_inf("getting serial port via mbedls)")
+            serial_port = HostTestPluginBase().check_serial_port_ready(self.port, target_id=self.target_id, timeout=self.polling_timeout)
+
         if serial_port is None:
             raise ConnectorPrimitiveException("Serial port not ready!")
 

test/test/test_conn_primitive_serial.py

@@ -0,0 +1,86 @@
+# Copyright (c) 2018-2021, Arm Limited and affiliates.
+# SPDX-License-Identifier: Apache-2.0
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import unittest
+import mock
+
+from mbed_os_tools.test.host_tests_conn_proxy.conn_primitive_serial import SerialConnectorPrimitive
+from mbed_os_tools.test.host_tests_conn_proxy.conn_primitive import ConnectorPrimitiveException
+
+@mock.patch("mbed_os_tools.test.host_tests_conn_proxy.conn_primitive_serial.Serial")
+@mock.patch("mbed_os_tools.test.host_tests_plugins.host_test_plugins.detect")
+class ConnPrimitiveSerialTestCase(unittest.TestCase):
+    def test_provided_serial_port_used_with_target_id(self, mock_detect, mock_serial):
+        platform_name = "irrelevant"
+        target_id = "1234"
+        port = "COM256"
+        baudrate = "9600"
+
+        # The mock list_mbeds() call needs to return a list of dictionaries,
+        # and each dictionary must have a "serial_port", or else the
+        # check_serial_port_ready() function we are testing will sleep waiting
+        # for the serial port to become ready.
+        mock_detect.create().list_mbeds.return_value = [
+            {"target_id": target_id,
+             "serial_port": port,
+             "platform_name": platform_name},
+        ]
+
+        # Set skip_reset to avoid the use of a physical serial port.
+        config = {
+            "port": port,
+            "baudrate": baudrate,
+            "image_path": "test.bin",
+            "platform_name": "kaysixtyfoureff",
+            "target_id": "9900",
+            "skip_reset": True,
+        }
+        connector = SerialConnectorPrimitive("SERI", port, baudrate, config=config)
+
+        mock_detect.create().list_mbeds.assert_not_called()
+
+    def test_discovers_serial_port_with_target_id(self, mock_detect, mock_serial):
+        platform_name = "kaysixtyfoureff"
+        target_id = "9900"
+        port = "COM256"
+        baudrate = "9600"
+
+        mock_detect.create().list_mbeds.return_value = [
+            {"target_id": target_id,
+             "serial_port": port,
+             "platform_name": platform_name},
+        ]
+
+        # Set skip_reset to avoid the use of a physical serial port. Don't pass
+        # in a port, so that auto-detection based on target_id will find the
+        # port for us (using our mock list_mbeds data).
+        config = {
+            "port": None,
+            "baudrate": baudrate,
+            "image_path": "test.bin",
+            "platform_name": platform_name,
+            "target_id": target_id,
+            "skip_reset": True,
+        }
+        try:
+            connector = SerialConnectorPrimitive("SERI", None, baudrate, config=config)
+        except ConnectorPrimitiveException:
+            # lol bad
+            pass
+
+        mock_detect.create().list_mbeds.assert_called_once()
+
+if __name__ == '__main__':
+      unittest.main()