Use testify, write a couple more tests, and start a major refactor.

internal/mappingrules/rule_target_button.go

@@ -0,0 +1,31 @@
+package mappingrules
+
+import "github.com/holoplot/go-evdev"
+
+type RuleTargetButton struct {
+	RuleTargetBase
+}
+
+func NewRuleTargetButton(device_name string, device *evdev.InputDevice, code evdev.EvCode, inverted bool) *RuleTargetButton {
+	return &RuleTargetButton{
+		RuleTargetBase: NewRuleTargetBase(device_name, device, code, inverted),
+	}
+}
+
+func (target *RuleTargetButton) NormalizeValue(value int32) int32 {
+	if target.Inverted {
+		if value == 0 {
+			return 1
+		}
+		return 0
+	}
+	return value
+}
+
+func (target *RuleTargetButton) CreateEvent(value int32, mode *string) *evdev.InputEvent {
+	return &evdev.InputEvent{
+		Type:  evdev.EV_KEY,
+		Code:  target.Code,
+		Value: value,
+	}
+}