test: controls: control_info_map: Test default constructor

ControlInfoMap can be default-constructed. In that case, some of its
members (like idmap_) can be a nullptr, and ControlInfoMap.find() will segfault.

Add a test with a default constructed ControlInfoMap to cover this.

Signed-off-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
Reviewed-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
Reviewed-by: Umang Jain <umang.jain@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

test/controls/control_info_map.cpp

@@ -75,6 +75,13 @@ protected:
 			return TestFail;
 		}
 
+		/* Test looking up a control on a default-constructed infoMap */
+		const ControlInfoMap emptyInfoMap;
+		if (emptyInfoMap.find(12345) != emptyInfoMap.end()) {
+			cerr << "find() on empty ControlInfoMap failed" << endl;
+			return TestFail;
+		}
+
 		return TestPass;
 	}
 };