test: control_list: Check for Brightness presence

The current test verifies that after adding a new control to a list
already populated with one control the new one is present.

However the test wrongly tests for its presence twice instead of
making sure the existing control is still there.

Fix this by checking for the presence of both controls after the
update, and fix the error message accordingly.

Fixes: a8c40942b9 ("libcamera: controls: Improve the API towards applications")
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
Reviewed-by: Hirokazu Honda <hiroh@chromium.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>

test/controls/control_list.cpp

@@ -108,9 +108,10 @@ protected:
 		list.set(controls::Brightness, 0.0f);
 		list.set(controls::Contrast, 1.5f);
 
-		if (!list.contains(controls::Contrast) ||
+		if (!list.contains(controls::Brightness) ||
 		    !list.contains(controls::Contrast)) {
-			cout << "List should contain Contrast control" << endl;
+			cout << "List should contain Brightness and Contrast controls"
+			     << endl;
 			return TestFail;
 		}