riotctrl_shell.tests: rewrite Mock to detect missing check_term

`check_term` calls `run_term` of the `ctrl` if necessary.

dist/pythonlibs/riotctrl_shell/tests/common.py

@@ -4,25 +4,27 @@
 # General Public License v2.1. See the file LICENSE in the top level
 # directory for more details.
 
+import contextlib
+
 
 class MockSpawn():
-    def __init__(self, *args, **kwargs):
+    def __init__(self, ctrl, *args, **kwargs):
+        self.ctrl = ctrl
+        self.last_command = None
         # set some expected attributes
         self.before = None
         self.echo = False
-        self.output = None
-        self.last_command = None
 
     def sendline(self, line, *args, **kwargs):
         self.last_command = line
-        if self.output is None:
+        if self.ctrl.output is None:
             # just echo last input for before (what replwrap is assembling
             # output from)
             self.before = line
         else:
             # use pre-configured output in case command expects a specific
             # output
-            self.before = self.output
+            self.before = self.ctrl.output
 
     def expect_exact(self, *args, **kwargs):
         # always match on prompt with replwrap
@@ -34,11 +36,26 @@ class MockRIOTCtrl():
     Mock RIOT ctrl
     """
     def __init__(self, *args, **kwargs):
-        self.term = MockSpawn()
+        self.term = None
+        self.output = None
         self.last_command = None
 
+    @contextlib.contextmanager
+    def run_term(self, reset=True, **startkwargs):
+        try:
+            self.start_term(**startkwargs)
+            yield self.term
+        finally:
+            self.stop_term()
+
+    def start_term(self, **spawnkwargs):
+        self.term = MockSpawn(self)
+
+    def stop_term(self):
+        pass
+
 
 def init_ctrl(output=None):
     rc = MockRIOTCtrl("foobar", env={"BOARD": "native"})
-    rc.term.output = output
+    rc.output = output
     return rc