Add test for invalid priority levels to npq.

npq/lib_test.go

@@ -48,6 +48,26 @@ func TestSendClosedPanic(t *testing.T) {
 	q.Send(1, 1)
 }
 
+func TestTooLowPriorityPanic(t *testing.T) {
+	testInvalidPriorityPanic(t, 0)
+}
+
+func TestTooHighPriorityPanic(t *testing.T) {
+	testInvalidPriorityPanic(t, 3)
+}
+
+func testInvalidPriorityPanic(t *testing.T, invalid int) {
+	t.Parallel()
+	defer func() {
+		if r := recover(); r == nil {
+			t.Errorf("sending with invalid priority did not panic")
+		}
+	}()
+	q := npq.Make[int, int](4, 1, 2)
+	q.Send(invalid, 1)
+
+}
+
 func TestRecvClosed(t *testing.T) {
 	t.Parallel()
 	q := npq.Make[int, int](4, 1, 2)