Acceptance tests: Extract _console_interaction()

Since we are going to re-use the code shared between
wait_for_console_pattern() and exec_command_and_wait_for_pattern(),
extract the common part into a local function.
Tested-by: NNiek Linnenbank <nieklinnenbank@gmail.com>
Signed-off-by: NPhilippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: NLiam Merwick <liam.merwick@oracle.com>
Tested-by: NLiam Merwick <liam.merwick@oracle.com>
Reviewed-by: NWainer dos Santos Moschetta <wainersm@redhat.com>
Message-Id: <20200120235159.18510-3-f4bug@amsat.org>
Signed-off-by: NPhilippe Mathieu-Daudé <philmd@redhat.com>

tests/acceptance/avocado_qemu/__init__.py

@@ -55,19 +55,14 @@ def pick_default_qemu_bin(arch=None):
         return qemu_bin_from_src_dir_path
 
 
-def wait_for_console_pattern(test, success_message, failure_message=None):
-    """
-    Waits for messages to appear on the console, while logging the content
-
-    :param test: an Avocado test containing a VM that will have its console
-                 read and probed for a success or failure message
-    :type test: :class:`avocado_qemu.Test`
-    :param success_message: if this message appears, test succeeds
-    :param failure_message: if this message appears, test fails
-    """
+def _console_interaction(test, success_message, failure_message,
+                         send_string):
     console = test.vm.console_socket.makefile()
     console_logger = logging.getLogger('console')
     while True:
+        if send_string:
+            test.vm.console_socket.sendall(send_string.encode())
+            send_string = None # send only once
         msg = console.readline().strip()
         if not msg:
             continue
@@ -79,6 +74,17 @@ def wait_for_console_pattern(test, success_message, failure_message=None):
             fail = 'Failure message found in console: %s' % failure_message
             test.fail(fail)
 
+def wait_for_console_pattern(test, success_message, failure_message=None):
+    """
+    Waits for messages to appear on the console, while logging the content
+
+    :param test: an Avocado test containing a VM that will have its console
+                 read and probed for a success or failure message
+    :type test: :class:`avocado_qemu.Test`
+    :param success_message: if this message appears, test succeeds
+    :param failure_message: if this message appears, test fails
+    """
+    _console_interaction(test, success_message, failure_message, None)
 
 def exec_command_and_wait_for_pattern(test, command,
                                       success_message, failure_message=None):
@@ -94,10 +100,7 @@ def exec_command_and_wait_for_pattern(test, command,
     :param success_message: if this message appears, test succeeds
     :param failure_message: if this message appears, test fails
     """
-    command += '\r'
-    test.vm.console_socket.sendall(command.encode())
-    wait_for_console_pattern(test, success_message, failure_message)
-
+    _console_interaction(test, success_message, failure_message, command + '\r')
 
 class Test(avocado.Test):
     def _get_unique_tag_val(self, tag_name):