For speech rate in settings up/down move by 10, left/right move by 1. Easier to get settings right without having to hold doown the arrow keys lol.

internal/interaction/session_test.go

@@ -17,7 +17,20 @@
 
 package interaction
 
-import "testing"
+import (
+	"math"
+	"testing"
+)
+
+func TestInvalidNumberUpDownStepRejected(t *testing.T) {
+	for _, step := range []float64{-1, math.NaN(), math.Inf(1), math.Inf(-1)} {
+		form := test_form()
+		form.Tabs[0].Controls[1].UpDownStep = step
+		if _, err := New_session(form); err == nil {
+			t.Fatalf("invalid Up/Down step %v accepted", step)
+		}
+	}
+}
 
 func test_form() Form {
 	return Form{Type: TabForm, Title: "Settings", Tabs: []Tab{