Bot: Allow variadic functions to have empty trailing arguments

bot/ctx_call.go

@@ -277,6 +277,12 @@ func (ctx *Context) callMessageCreate(mc *gateway.MessageCreateEvent) error {
 	if argdelta := len(arguments) - len(cmd.Arguments); argdelta != 0 {
 		var err error // no err if nil
 
+		// If the function is variadic, then we can allow the last argument to
+		// be empty.
+		if cmd.Variadic {
+			argdelta++
+		}
+
 		switch {
 		// If there aren't enough arguments given.
 		case argdelta < 0:

bot/ctx_plumb_test.go

@@ -20,9 +20,7 @@ func (h *hasPlumb) Normal(_ *gateway.MessageCreateEvent) error {
 	return nil
 }
 
-func (h *hasPlumb) PーPlumber(
-	_ *gateway.MessageCreateEvent, c Content) error {
-
+func (h *hasPlumb) PーPlumber(_ *gateway.MessageCreateEvent, c RawArguments) error {
 	h.Plumbed = string(c)
 	return nil
 }

bot/ctx_test.go

@@ -214,9 +214,9 @@ func TestContext(t *testing.T) {
 
 	t.Run("call command custom trailing manual parser", func(t *testing.T) {
 		ctx.HasPrefix = NewPrefix("!")
-		expects := []string{"arikawa"}
+		expects := []string{}
 
-		if err := testReturn(expects, "!trailCustom hime arikawa"); err != nil {
+		if err := testReturn(expects, "!trailCustom hime_arikawa"); err != nil {
 			t.Fatal("Unexpected call error:", err)
 		}
 	})