core: do not clear cache on ClearSession

core/src/apps/homescreen/__init__.py

@@ -92,8 +92,12 @@ async def handle_Cancel(ctx: wire.Context, msg: Cancel) -> NoReturn:
 
 
 async def handle_ClearSession(ctx: wire.Context, msg: ClearSession) -> Success:
-    cache.clear()
-    return Success(message="Session cleared")
+    """
+    This is currently a no-op on T. This should be called LockSession/LockDevice
+    and lock the device. In other words the cache should stay but the PIN should
+    be forgotten and required again.
+    """
+    return Success()
 
 
 async def handle_Ping(ctx: wire.Context, msg: Ping) -> Success:

core/tests/test_storage.cache.py

@@ -76,24 +76,6 @@ class TestStorageCache(unittest.TestCase):
         call_Initialize(session_id=new_session_id)
         self.assertIsNone(cache.get(KEY))
 
-    @mock_storage
-    def test_ClearSession(self):
-        def call_Initialize(**kwargs):
-            msg = Initialize(**kwargs)
-            return await_result(handle_Initialize(DUMMY_CONTEXT, msg))
-
-        def call_ClearSession():
-            return await_result(handle_ClearSession(DUMMY_CONTEXT, ClearSession()))
-
-        session_id = call_Initialize().session_id
-        cache.set(KEY, "hello")
-        self.assertEqual(cache.get(KEY), "hello")
-
-        call_ClearSession()
-        self.assertIsNone(cache.get(KEY))
-        new_session_id = cache.get_session_id()
-        self.assertNotEqual(session_id, new_session_id)
-
 
 if __name__ == "__main__":
     unittest.main()

tests/device_tests/test_session_id_and_passphrase.py

@@ -98,23 +98,6 @@ def test_session_enable_passphrase(client):
     assert _get_xpub(client, passphrase="A") == XPUB_PASSPHRASE_A
 
 
-@pytest.mark.skip_ui
-def test_clear_session(client):
-    session_id = _init_session(client)
-
-    # session id remains the same
-    new_session_id = _init_session(client, session_id=session_id)
-    assert session_id == new_session_id
-
-    # by clearing the session, the id is lost
-    response = client.call(messages.ClearSession())
-    assert isinstance(response, messages.Success)
-
-    # cannot resume the old session now
-    new_session_id = _init_session(client, session_id=session_id)
-    assert session_id != new_session_id
-
-
 @pytest.mark.skip_ui
 @pytest.mark.setup_client(passphrase=True)
 def test_clear_session_passphrase(client):
@@ -124,9 +107,9 @@ def test_clear_session_passphrase(client):
     # now the passphrase is cached
     assert _get_xpub(client, passphrase=None) == XPUB_PASSPHRASE_A
 
-    # ClearSession will erase the cached passphrase
-    response = client.call(messages.ClearSession())
-    assert isinstance(response, messages.Success)
+    # Erase the cached passphrase
+    response = client.call(messages.Initialize())
+    assert isinstance(response, messages.Features)
 
     # we have to enter passphrase again
     assert _get_xpub(client, passphrase="A") == XPUB_PASSPHRASE_A