How to manually set colour of dots in R using tmap

I'm trying to create a map showing the location of wells based on some defined categories. I have categorized each well's water level relative to their full record, categorizing the water levels into terms "Highest-ever", "above-normal", "normal", "below-normal", "Lowest-ever". Using tmap, I would like to show each of these conditions using the following colors "Highest-ever" = dark blue, "above-normal" = light blue, "normal"=green,"below-normal"=yellow, "Lowest-ever" = red

So far I have created an sf file for mapping

Library(tidyverse)
library(sf)
library(spData)
Library(tmap)
Library(tmaptools)

My data

test <- structure(list(well = c(3698L, 3697L, 4702L, 15001L, 1501L, 3737L, 
1674L, 5988L, 1475L, 15017L), con = c("N", "B", "H", "B", "L", 
"B", "N", "A", "N", "B"), x = c(2834091L, 2838342L, 2802911L, 
2845228L, 2834408L, 2834452L, 2838641L, 2834103L, 2803192L, 2929417L
), y = c(6166870L, 6165512L, 6125649L, 6174527L, 6161309L, 6168216L, 
6170055L, 6164397L, 6140763L, 6227467L)), row.names = c(NA, -10L
), class = c("tbl_df", "tbl", "data.frame"))

Create sf file for mapping

test_sf <-test %>% 
  st_as_sf(coords = c("x","y"),crs = 27200,agr="constant")

Obtain background map

HB_map <- nz %>% 
  filter(Name=="Hawke's Bay") %>% 
  read_osm(type = "stamen-terrain")

Plot data over map

qtm(HB_map)+ #this is part of tmap and used to draw a thematic map plot
  tm_shape(nz %>% filter(Name=="Hawke's Bay"))+ #define data source
  tm_borders(col = "grey40", lwd = 2, lty = "solid", alpha = NA)+
  tm_shape(test_sf)+  
tm_dots("con",palette=c(H='blue',A='cyan',N='green',B='yellow',L='red'),stretch.palette = FALSE,size = 0.4,shape =21)

The map produces the right colours but not associated with the correct categories. I could change the order of the colours but the map won't always contain each category and thus the colours would be wrongly assigned again (if that makes sense)

You can convert your con-column to factor. The default order of the levels will be alphabetic, that's how you can assign the colors. If a level is empty, it will still be included in the legend.

test_sf$con <- as.factor(test_sf$con)

tm_shape(nz %>% filter(Name=="Hawke's Bay"))+ #define data source
  tm_borders(col = "grey40", lwd = 2, lty = "solid", alpha = NA)+
  tm_shape(test_sf[test_sf$con != "H",])+  
  tm_dots(col = "con", palette=c(A='cyan', B='yellow', H='blue',L='red',N='green'), stretch.palette = FALSE,size = 0.4,shape =21)

(read_osm() doesn't work for me..)