diff --git a/app/boards/native_posix.overlay b/app/boards/native_posix.overlay
index 2c1ed79d..417141cc 100644
--- a/app/boards/native_posix.overlay
+++ b/app/boards/native_posix.overlay
@@ -11,8 +11,8 @@
 		compatible = "zmk,kscan-mock";
 		label = "KSCAN_MOCK";
 
-		rows = <2>;
-		columns = <2>;
+		rows = <4>;
+		columns = <12>;
 		exit-after;
 	};
 };
diff --git a/app/tests/mercury/behavior_keymap.dtsi b/app/tests/mercury/behavior_keymap.dtsi
new file mode 100644
index 00000000..c285886c
--- /dev/null
+++ b/app/tests/mercury/behavior_keymap.dtsi
@@ -0,0 +1 @@
+#include "../boards/shields/mercury/mercury.keymap"
diff --git a/app/tests/mercury/sdDn_dUp/events.patterns b/app/tests/mercury/sdDn_dUp/events.patterns
new file mode 100644
index 00000000..a85b9534
--- /dev/null
+++ b/app/tests/mercury/sdDn_dUp/events.patterns
@@ -0,0 +1,6 @@
+s/.*mo_keymap_binding/mo/p
+s/.*hid_listener_keycode/kp/p
+s/.*decide_hold_tap/ht_decide/p
+s/.*on_hold_tap_binding/ht_binding/p
+// s/.*keymap_apply_position_state/pos_state/p
+s/.*behavior_queue_process_next/queue_process_next/p
diff --git a/app/tests/mercury/sdDn_dUp/keycode_events.snapshot b/app/tests/mercury/sdDn_dUp/keycode_events.snapshot
new file mode 100644
index 00000000..3f2f6c4b
--- /dev/null
+++ b/app/tests/mercury/sdDn_dUp/keycode_events.snapshot
@@ -0,0 +1,10 @@
+pos_state: layer: 0, position: 14, binding name: S_MACRO_TAP, pressed: 1
+ht_binding_pressed: 14 new undecided hold_tap
+ht_decide: 14 decided hold-interrupt (tap-unless-interrupted decision moment other-key-down)
+pos_state: layer: 0, position: 15, binding name: D_LAYER_TAP, pressed: 1
+ht_binding_pressed: 15 new undecided hold_tap
+queue_process_next: Invoking MO: 0x08 0x00
+mo_pressed: position 0 layer 8
+queue_process_next: Processing next queued behavior in 100ms
+ht_decide: 15 decided tap (tap-unless-interrupted decision moment other-key-down)
+kp_pressed: usage_page 0x07 keycode 0x07 implicit_mods 0x00 explicit_mods 0x00
diff --git a/app/tests/mercury/sdDn_dUp/native_posix.keymap b/app/tests/mercury/sdDn_dUp/native_posix.keymap
new file mode 100644
index 00000000..ca4a8a59
--- /dev/null
+++ b/app/tests/mercury/sdDn_dUp/native_posix.keymap
@@ -0,0 +1,17 @@
+#include <dt-bindings/zmk/keys.h>
+#include <behaviors.dtsi>
+#include <dt-bindings/zmk/kscan_mock.h>
+#include "../behavior_keymap.dtsi"
+
+&kscan {
+	events = <
+        //ZMK_MOCK_PRESS(  0,1,10)
+		//ZMK_MOCK_RELEASE(0,1,10)
+
+		ZMK_MOCK_PRESS(  1,2,5)
+		ZMK_MOCK_PRESS(  1,3,5)
+		ZMK_MOCK_PRESS(  1,7,5)
+		//ZMK_MOCK_RELEASE(1,2,5)
+		//ZMK_MOCK_RELEASE(1,3,5)
+	>;
+};
\ No newline at end of file