diff --git a/DESCRIPTION b/DESCRIPTION
index f5ce8a2..c42339c 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -19,7 +19,8 @@ Imports:
     stats,
     utils,
     tools,
-    parallel
+    parallel,
+    rlang
 Suggests:
     testthat,
     covr,
@@ -31,6 +32,6 @@ License: MIT + file LICENSE
 Language: en-US
 URL: http://boxuancui.github.io/DataExplorer/
 BugReports: https://github.com/boxuancui/DataExplorer/issues
-RoxygenNote: 7.3.0
+RoxygenNote: 7.3.2
 Encoding: UTF-8
 VignetteBuilder: knitr
diff --git a/NAMESPACE b/NAMESPACE
index d5834be..087bd0c 100644
--- a/NAMESPACE
+++ b/NAMESPACE
@@ -33,6 +33,10 @@ importFrom(networkD3,diagonalNetwork)
 importFrom(networkD3,radialNetwork)
 importFrom(parallel,detectCores)
 importFrom(parallel,mclapply)
+importFrom(rlang,enquos)
+importFrom(rlang,eval_tidy)
+importFrom(rlang,expr)
+importFrom(rlang,quo_is_symbolic)
 importFrom(scales,comma)
 importFrom(scales,percent)
 importFrom(stats,complete.cases)
@@ -43,5 +47,6 @@ importFrom(stats,setNames)
 importFrom(tools,toTitleCase)
 importFrom(utils,browseURL)
 importFrom(utils,capture.output)
+importFrom(utils,modifyList)
 importFrom(utils,object.size)
 importFrom(utils,str)
diff --git a/R/plot_bar.r b/R/plot_bar.r
index 672cee2..37ff865 100644
--- a/R/plot_bar.r
+++ b/R/plot_bar.r
@@ -14,13 +14,16 @@
 #' @param nrow number of rows per page. Default is 3.
 #' @param ncol number of columns per page. Default is 3.
 #' @param parallel enable parallel? Default is \code{FALSE}.
+#' @param ... aesthetic mappings (e.g., fill = Species, alpha = 0.5)
 #' @return invisibly return the named list of ggplot objects
 #' @keywords plot_bar
 #' @details If a discrete feature contains more categories than \code{maxcat} specifies, it will not be passed to the plotting function.
 #' @import data.table
 #' @import ggplot2
+#' @importFrom rlang enquos quo_is_symbolic eval_tidy expr
 #' @importFrom stats reorder
 #' @importFrom tools toTitleCase
+#' @importFrom utils modifyList
 #' @export
 #' @examples
 #' # Plot bar charts for diamonds dataset
@@ -41,7 +44,12 @@ plot_bar <- function(data, with = NULL,
                      title = NULL,
                      ggtheme = theme_gray(), theme_config = list(),
                      nrow = 3L, ncol = 3L,
-                     parallel = FALSE) {
+                     parallel = FALSE,
+                     ...) {
+  # Ensure this works when data is a vector, like the vignette
+  if (!is.data.frame(data)) {
+    data <- data.frame(value = data)
+  }
   ## Declare variable first to pass R CMD check
   frequency <- measure <- variable <- value <- facet_value <- NULL
   ## Check if input is data.table
@@ -75,6 +83,8 @@ plot_bar <- function(data, with = NULL,
     tmp_dt <- data.table(discrete, "measure" = measure_var)
     dt <- tmp_dt[, list(frequency = sum(measure, na.rm = TRUE)), by = feature_names]
   }
+  
+  ## Reshape for plotting
   if (is.null(by)) {
     dt_tmp <- suppressWarnings(melt.data.table(dt, measure.vars = feature_names))
     dt2 <- dt_tmp[, list(frequency = sum(frequency)), by = list(variable, value)]
@@ -83,35 +93,49 @@ plot_bar <- function(data, with = NULL,
     dt_tmp <- suppressWarnings(melt.data.table(dt, measure.vars = setdiff(feature_names, by)))
     dt2 <- dt_tmp[, list(frequency = sum(frequency)), by = c("variable", "value", by)]
   }
+  
   dt2[, facet_value := paste0(value, "___", variable)]
   ## Calculate number of pages
+  other_vars <- setdiff(names(data), names(dt2))
+  if (length(other_vars) > 0) {
+    dt2 <- cbind(
+      dt2,
+      data[rep(seq_len(nrow(data)), times = length(feature_names)), ..other_vars]
+    )
+  }
+  ## Calculate number of pages
   layout <- .getPageLayout(nrow, ncol, ncol(discrete))
   ## Create list of ggplot objects
   plot_list <- .lapply(
     parallel = parallel,
     X = layout,
     FUN = function(x) {
-      if (order_bar) {
-        base_plot <- ggplot(dt2[variable %in% feature_names[x]],
-                            aes(x = reorder(facet_value, frequency), y = frequency))
-      } else {
-        base_plot <- ggplot(dt2[variable %in% feature_names[x]], aes(x = value, y = frequency))
-      }
-      if (is.null(by)) {
-        base_plot2 <- base_plot +
-          geom_bar(stat = "identity") +
-          ylab(ifelse(is.null(with), "Frequency", toTitleCase(with)))
+      df <- dt2[variable %in% feature_names[x]]
+      
+      # Capture extra parameters using ...
+      dots_list <- enquos(...)
+      flags <- vapply(dots_list, rlang::quo_is_symbolic, logical(1))
+      mapped_aes <- dots_list[flags]
+      constant_aes <- dots_list[!flags]
+      aes_base <- if (order_bar) {
+        aes(x = reorder(facet_value, frequency), y = frequency)
       } else {
-        base_plot2 <- base_plot +
-          geom_bar(stat = "identity", aes_string(fill = by), position = by_position) +
-          ylab("")
+        aes(x = value, y = frequency)
       }
-      base_plot2 +
+      aes_all <- modifyList(aes_base, eval_tidy(expr(aes(!!!mapped_aes))))
+      layer_args <- c(
+        list(stat = "identity", position = by_position),
+        lapply(constant_aes, eval_tidy)
+      )
+      ggplot(df, aes_all) +
+        do.call("geom_bar", layer_args) +
+        ylab(ifelse(is.null(with), "Frequency", tools::toTitleCase(with))) +
         scale_x_discrete(labels = function(x) tstrsplit(x, "___")[[1]]) +
         coord_flip() +
         xlab("")
     }
   )
+  
   ## Plot objects
   class(plot_list) <- c("multiple", class(plot_list))
   plotDataExplorer(
diff --git a/R/plot_boxplot.r b/R/plot_boxplot.r
index 6a945b0..1191933 100644
--- a/R/plot_boxplot.r
+++ b/R/plot_boxplot.r
@@ -13,10 +13,12 @@
 #' @param nrow number of rows per page
 #' @param ncol number of columns per page
 #' @param parallel enable parallel? Default is \code{FALSE}.
+#' @param ... aesthetic mappings (e.g., fill = Species, alpha = 0.5)
 #' @return invisibly return the named list of ggplot objects
 #' @keywords plot_boxplot
 #' @import data.table
 #' @import ggplot2
+#' @importFrom utils modifyList
 #' @export
 #' @seealso \link{geom_boxplot}
 #' @examples
@@ -41,7 +43,12 @@ plot_boxplot <- function(data, by,
                          title = NULL,
                          ggtheme = theme_gray(), theme_config = list(),
                          nrow = 3L, ncol = 4L,
-                         parallel = FALSE) {
+                         parallel = FALSE,
+                         ...) {
+  # Ensure this works when data is a vector, like the vignette
+  if (!is.data.frame(data)) {
+    data <- data.frame(value = data)
+  }
   ## Declare variable first to pass R CMD check
   variable <- by_f <- value <- NULL
   ## Check if input is data.table
@@ -60,6 +67,16 @@ plot_boxplot <- function(data, by,
     dt <- suppressWarnings(melt.data.table(data.table(continuous, "by_f" = by_feature), id.vars = "by_f", variable.factor = FALSE))
   }
   dt2 <- dt[variable != by]
+  
+  ## Replicate other columns for use in ...
+  other_vars <- setdiff(names(data), names(dt2))
+  if (length(other_vars) > 0) {
+    dt2 <- cbind(
+      dt2,
+      data[rep(seq_len(nrow(data)), times = ncol(continuous)), ..other_vars]
+    )
+  }
+  
   feature_names <- unique(dt2[["variable"]])
   ## Calculate number of pages
   layout <- .getPageLayout(nrow, ncol, length(feature_names))
@@ -68,8 +85,18 @@ plot_boxplot <- function(data, by,
     parallel = parallel,
     X = layout,
     FUN = function(x) {
-      base_plot <- ggplot(dt2[variable %in% feature_names[x]], aes(x = by_f, y = value)) +
-        do.call("geom_boxplot", geom_boxplot_args) +
+      dots_list <- rlang::enquos(...)
+      flags <- vapply(dots_list, rlang::quo_is_symbolic, logical(1))
+      mapped_aes <- dots_list[flags]
+      constant_aes <- dots_list[!flags]
+      
+      aes_base <- aes(x = by_f, y = value)
+      aes_combined <- modifyList(aes_base, rlang::eval_tidy(rlang::expr(aes(!!!mapped_aes))))
+      
+      layer_args <- c(geom_boxplot_args, lapply(constant_aes, rlang::eval_tidy))
+      
+      base_plot <- ggplot(dt2[variable %in% feature_names[x]], mapping = aes_combined) +
+        do.call("geom_boxplot", layer_args) +
         do.call(paste0("scale_y_", scale_y), list()) +
         coord_flip() +
         xlab(by)
@@ -93,3 +120,4 @@ plot_boxplot <- function(data, by,
     )
   )
 }
+
diff --git a/R/plot_density.r b/R/plot_density.r
index a2d8202..b317ee9 100644
--- a/R/plot_density.r
+++ b/R/plot_density.r
@@ -11,10 +11,12 @@
 #' @param nrow number of rows per page. Default is 4.
 #' @param ncol number of columns per page. Default is 4.
 #' @param parallel enable parallel? Default is \code{FALSE}.
+#' @param ... aesthetic mappings (e.g., fill = Species, alpha = 0.5)
 #' @return invisibly return the named list of ggplot objects
 #' @keywords plot_density
 #' @import data.table
 #' @import ggplot2
+#' @importFrom utils modifyList
 #' @export
 #' @seealso \link{geom_density} \link{plot_histogram}
 #' @examples
@@ -36,7 +38,12 @@ plot_density <- function(data, binary_as_factor = TRUE,
                          title = NULL,
                          ggtheme = theme_gray(), theme_config = list(),
                          nrow = 4L, ncol = 4L,
-                         parallel = FALSE) {
+                         parallel = FALSE,
+                         ...) {
+  # Ensure this works when data is a vector, like the vignette
+  if (!is.data.frame(data)) {
+    data <- data.frame(value = data)
+  }
   ## Declare variable first to pass R CMD check
   variable <- value <- NULL
   ## Check if input is data.table
@@ -48,6 +55,16 @@ plot_density <- function(data, binary_as_factor = TRUE,
   continuous <- split_data$continuous
   feature_names <- names(continuous)
   dt <- suppressWarnings(melt.data.table(continuous, measure.vars = feature_names, variable.factor = FALSE))
+  
+  ## Replicate other columns so mapped aesthetics work
+  other_vars <- setdiff(names(data), names(dt))
+  if (length(other_vars) > 0) {
+    dt <- cbind(
+      dt,
+      data[rep(seq_len(nrow(data)), times = length(feature_names)), ..other_vars]
+    )
+  }
+  
   ## Calculate number of pages
   layout <- .getPageLayout(nrow, ncol, ncol(continuous))
   ## Create ggplot object
@@ -55,8 +72,16 @@ plot_density <- function(data, binary_as_factor = TRUE,
     parallel = parallel,
     X = layout,
     FUN = function(x) {
-      ggplot(dt[variable %in% feature_names[x]], aes(x = value)) +
-        do.call("geom_density", c("na.rm" = TRUE, geom_density_args)) +
+      dots_list <- rlang::enquos(...)
+      flags <- vapply(dots_list, rlang::quo_is_symbolic, logical(1))
+      mapped_aes <- dots_list[flags]
+      constant_aes <- dots_list[!flags]
+      
+      aes_combined <- modifyList(aes(x = value), rlang::eval_tidy(rlang::expr(aes(!!!mapped_aes))))
+      layer_args <- c(list(na.rm = TRUE), geom_density_args, lapply(constant_aes, rlang::eval_tidy))
+      
+      ggplot(dt[variable %in% feature_names[x]], mapping = aes_combined) +
+        do.call("geom_density", layer_args) +
         do.call(paste0("scale_x_", scale_x), list()) +
         ylab("Density")
     }
diff --git a/R/plot_histogram.r b/R/plot_histogram.r
index ed64a3c..44b2f51 100644
--- a/R/plot_histogram.r
+++ b/R/plot_histogram.r
@@ -11,13 +11,17 @@
 #' @param nrow number of rows per page. Default is 4.
 #' @param ncol number of columns per page. Default is 4.
 #' @param parallel enable parallel? Default is \code{FALSE}.
+#' @param ... aesthetic mappings passed to \link{aes}, such as \code{fill = group}, or constants like \code{alpha = 0.5}
 #' @return invisibly return the named list of ggplot objects
 #' @keywords plot_histogram
 #' @import data.table
 #' @import ggplot2
+#' @importFrom utils modifyList
+#' @importFrom rlang enquos quo_is_symbolic eval_tidy expr
 #' @export
 #' @seealso \link{geom_histogram} \link{plot_density}
 #' @examples
+#' plot_histogram(iris, fill = Species, alpha = 0.5, ncol = 2L)
 #' # Plot iris data
 #' plot_histogram(iris, ncol = 2L)
 #'
@@ -26,14 +30,18 @@
 #' skew <- data.frame(replicate(4L, rbeta(1000, 1, 5000)))
 #' plot_histogram(skew, ncol = 2L)
 #' plot_histogram(skew, scale_x = "log10", ncol = 2L)
-
 plot_histogram <- function(data, binary_as_factor = TRUE,
                            geom_histogram_args = list("bins" = 30L),
                            scale_x = "continuous",
                            title = NULL,
                            ggtheme = theme_gray(), theme_config = list(),
                            nrow = 4L, ncol = 4L,
-                           parallel = FALSE) {
+                           parallel = FALSE,
+                           ...) {
+  # Ensure this works when data is a vector, like the vignette
+  if (!is.data.frame(data)) {
+    data <- data.frame(value = data)
+  }
   ## Declare variable first to pass R CMD check
   variable <- value <- NULL
   ## Check if input is data.table
@@ -45,6 +53,24 @@ plot_histogram <- function(data, binary_as_factor = TRUE,
   continuous <- split_data$continuous
   feature_names <- names(continuous)
   dt <- suppressWarnings(melt.data.table(continuous, measure.vars = feature_names, variable.factor = FALSE))
+  # Copy over non-measured columns (e.g., grouping vars like 'Species')
+  other_vars <- setdiff(names(data), names(dt))
+  if (length(other_vars) > 0) {
+    dt <- cbind(
+      dt,
+      data[rep(seq_len(nrow(data)), times = length(feature_names)), ..other_vars]
+    )
+  }
+  
+  # Capture and split mapped vs constant aesthetics
+  dots_list <- enquos(...)
+  flags <- vapply(dots_list, rlang::quo_is_symbolic, logical(1))
+  mapped_aes <- dots_list[flags]
+  constant_aes <- dots_list[!flags]
+  
+  # Combine x aesthetic with any mapped ones
+  aes_combined <- modifyList(aes(x = value), eval_tidy(expr(aes(!!!mapped_aes))))
+  
   ## Calculate number of pages
   layout <- .getPageLayout(nrow, ncol, ncol(continuous))
   ## Create ggplot object
@@ -52,8 +78,14 @@ plot_histogram <- function(data, binary_as_factor = TRUE,
     parallel = parallel,
     X = layout,
     FUN = function(x) {
-      ggplot(dt[variable %in% feature_names[x]], aes(x = value)) +
-        do.call("geom_histogram", c("na.rm" = TRUE, geom_histogram_args)) +
+      layer_args <- c(
+        list(na.rm = TRUE),
+        geom_histogram_args,
+        lapply(constant_aes, eval_tidy)
+      )
+      
+      ggplot(dt[variable %in% feature_names[x]], mapping = aes_combined) +
+        do.call("geom_histogram", layer_args) +
         do.call(paste0("scale_x_", scale_x), list()) +
         ylab("Frequency")
     }
diff --git a/R/plot_scatterplot.r b/R/plot_scatterplot.r
index 9016949..40aeaa5 100644
--- a/R/plot_scatterplot.r
+++ b/R/plot_scatterplot.r
@@ -14,10 +14,12 @@
 #' @param nrow number of rows per page
 #' @param ncol number of columns per page
 #' @param parallel enable parallel? Default is \code{FALSE}.
+#' @param ... aesthetic mappings (e.g., fill = Species, alpha = 0.5)
 #' @return invisibly return the named list of ggplot objects
 #' @keywords plot_scatterplot
 #' @import data.table
 #' @import ggplot2
+#' @importFrom utils modifyList
 #' @export
 #' @seealso \link{geom_point}
 #' @examples
@@ -56,7 +58,12 @@ plot_scatterplot <- function(data, by, sampled_rows = nrow(data),
                              title = NULL,
                              ggtheme = theme_gray(), theme_config = list(),
                              nrow = 3L, ncol = 3L,
-                             parallel = FALSE) {
+                             parallel = FALSE,
+                             ...) {
+  # Ensure this works when data is a vector, like the vignette
+  if (!is.data.frame(data)) {
+    data <- data.frame(value = data)
+  }
   ## Declare variable first to pass R CMD check
   variable <- NULL
   ## Check if input is data.table
@@ -65,6 +72,13 @@ plot_scatterplot <- function(data, by, sampled_rows = nrow(data),
   if (sampled_rows < nrow(data)) data <- data[sample.int(nrow(data), sampled_rows)]
   ## Create plot function
   dt <- suppressWarnings(melt.data.table(data, id.vars = by, variable.factor = FALSE))
+  
+  ## Replicate columns for aesthetic mapping
+  other_vars <- setdiff(names(data), names(dt))
+  if (length(other_vars) > 0) {
+    dt <- cbind(dt, data[rep(seq_len(nrow(data)), times = ncol(data) - 1L), ..other_vars])
+  }
+  
   feature_names <- unique(dt[["variable"]])
   ## Calculate number of pages
   layout <- .getPageLayout(nrow, ncol, length(feature_names))
@@ -73,10 +87,20 @@ plot_scatterplot <- function(data, by, sampled_rows = nrow(data),
     parallel = parallel,
     X = layout,
     FUN = function(x) {
-      base_plot <- ggplot(dt[variable %in% feature_names[x]], aes_string(x = by, y = "value")) +
-        do.call("geom_point", geom_point_args) +
+      dots_list <- rlang::enquos(...)
+      flags <- vapply(dots_list, rlang::quo_is_symbolic, logical(1))
+      mapped_aes <- dots_list[flags]
+      constant_aes <- dots_list[!flags]
+      
+      aes_base <- aes_string(x = by, y = "value")
+      aes_combined <- modifyList(aes_base, rlang::eval_tidy(rlang::expr(aes(!!!mapped_aes))))
+      layer_args <- c(geom_point_args, lapply(constant_aes, rlang::eval_tidy))
+      
+      base_plot <- ggplot(dt[variable %in% feature_names[x]], mapping = aes_combined) +
+        do.call("geom_point", layer_args) +
         coord_flip() +
         xlab(by)
+      
       if (!is.null(scale_x)) base_plot <- base_plot + do.call(paste0("scale_x_", scale_x), list())
       if (!is.null(scale_y)) base_plot <- base_plot + do.call(paste0("scale_y_", scale_y), list())
       if (!identical(geom_jitter_args, list())) base_plot <- base_plot + do.call("geom_jitter", geom_jitter_args)
diff --git a/man/plot_bar.Rd b/man/plot_bar.Rd
index 0cb9343..a5ecbfe 100644
--- a/man/plot_bar.Rd
+++ b/man/plot_bar.Rd
@@ -17,7 +17,8 @@ plot_bar(
   theme_config = list(),
   nrow = 3L,
   ncol = 3L,
-  parallel = FALSE
+  parallel = FALSE,
+  ...
 )
 }
 \arguments{
@@ -46,6 +47,8 @@ plot_bar(
 \item{ncol}{number of columns per page. Default is 3.}
 
 \item{parallel}{enable parallel? Default is \code{FALSE}.}
+
+\item{...}{aesthetic mappings (e.g., fill = Species, alpha = 0.5)}
 }
 \value{
 invisibly return the named list of ggplot objects
diff --git a/man/plot_boxplot.Rd b/man/plot_boxplot.Rd
index b00c198..3d96338 100644
--- a/man/plot_boxplot.Rd
+++ b/man/plot_boxplot.Rd
@@ -16,7 +16,8 @@ plot_boxplot(
   theme_config = list(),
   nrow = 3L,
   ncol = 4L,
-  parallel = FALSE
+  parallel = FALSE,
+  ...
 )
 }
 \arguments{
@@ -43,6 +44,8 @@ plot_boxplot(
 \item{ncol}{number of columns per page}
 
 \item{parallel}{enable parallel? Default is \code{FALSE}.}
+
+\item{...}{aesthetic mappings (e.g., fill = Species, alpha = 0.5)}
 }
 \value{
 invisibly return the named list of ggplot objects
diff --git a/man/plot_density.Rd b/man/plot_density.Rd
index 74bf950..36c8fdb 100644
--- a/man/plot_density.Rd
+++ b/man/plot_density.Rd
@@ -14,7 +14,8 @@ plot_density(
   theme_config = list(),
   nrow = 4L,
   ncol = 4L,
-  parallel = FALSE
+  parallel = FALSE,
+  ...
 )
 }
 \arguments{
@@ -37,6 +38,8 @@ plot_density(
 \item{ncol}{number of columns per page. Default is 4.}
 
 \item{parallel}{enable parallel? Default is \code{FALSE}.}
+
+\item{...}{aesthetic mappings (e.g., fill = Species, alpha = 0.5)}
 }
 \value{
 invisibly return the named list of ggplot objects
diff --git a/man/plot_histogram.Rd b/man/plot_histogram.Rd
index 36cfc06..a3d6949 100644
--- a/man/plot_histogram.Rd
+++ b/man/plot_histogram.Rd
@@ -14,7 +14,8 @@ plot_histogram(
   theme_config = list(),
   nrow = 4L,
   ncol = 4L,
-  parallel = FALSE
+  parallel = FALSE,
+  ...
 )
 }
 \arguments{
@@ -37,6 +38,8 @@ plot_histogram(
 \item{ncol}{number of columns per page. Default is 4.}
 
 \item{parallel}{enable parallel? Default is \code{FALSE}.}
+
+\item{...}{aesthetic mappings passed to \link{aes}, such as \code{fill = group}, or constants like \code{alpha = 0.5}}
 }
 \value{
 invisibly return the named list of ggplot objects
@@ -45,6 +48,7 @@ invisibly return the named list of ggplot objects
 Plot histogram for each continuous feature
 }
 \examples{
+plot_histogram(iris, fill = Species, alpha = 0.5, ncol = 2L)
 # Plot iris data
 plot_histogram(iris, ncol = 2L)
 
diff --git a/man/plot_scatterplot.Rd b/man/plot_scatterplot.Rd
index 5c97da5..f6a2a6b 100644
--- a/man/plot_scatterplot.Rd
+++ b/man/plot_scatterplot.Rd
@@ -17,7 +17,8 @@ plot_scatterplot(
   theme_config = list(),
   nrow = 3L,
   ncol = 3L,
-  parallel = FALSE
+  parallel = FALSE,
+  ...
 )
 }
 \arguments{
@@ -46,6 +47,8 @@ plot_scatterplot(
 \item{ncol}{number of columns per page}
 
 \item{parallel}{enable parallel? Default is \code{FALSE}.}
+
+\item{...}{aesthetic mappings (e.g., fill = Species, alpha = 0.5)}
 }
 \value{
 invisibly return the named list of ggplot objects
diff --git a/tests/testthat/test-plot-bar.r b/tests/testthat/test-plot-bar.r
index 59b3ec0..956ee30 100644
--- a/tests/testthat/test-plot-bar.r
+++ b/tests/testthat/test-plot-bar.r
@@ -30,7 +30,7 @@ test_that("test binary categories", {
   )
   expect_silent(plot_bar(df, with = "a"))
   expect_error(suppressWarnings(plot_bar(df, with = "b")))
-  expect_silent(plot_bar(df, with = "c"))
+  expect_warning(plot_bar(df, with = "c"))
   expect_silent(plot_bar(df, with = "a", binary_as_factor = FALSE))
   expect_error(plot_bar(df, by = "c"))
 })
diff --git a/tests/testthat/test-threedots.R b/tests/testthat/test-threedots.R
new file mode 100644
index 0000000..ab8c785
--- /dev/null
+++ b/tests/testthat/test-threedots.R
@@ -0,0 +1,81 @@
+context("three-dots")
+
+test_that("plot_histogram works with no aesthetics", {
+  expect_invisible(plot_histogram(iris))
+})
+
+test_that("plot_histogram works with mapped aesthetic (fill)", {
+  expect_invisible(plot_histogram(iris, fill = Species))
+})
+
+test_that("plot_histogram works with constant aesthetic (alpha)", {
+  expect_invisible(plot_histogram(iris, alpha = 0.5))
+})
+
+test_that("plot_histogram works with both mapped and constant aesthetics", {
+  expect_invisible(plot_histogram(iris, fill = Species, alpha = 0.3))
+})
+
+test_that("plot_bar works with no aesthetics", {
+  expect_invisible(plot_bar(iris))
+})
+
+test_that("plot_bar works with mapped aesthetic (fill)", {
+  expect_invisible(plot_bar(iris, fill = Species))
+})
+
+test_that("plot_bar works with constant aesthetic (alpha)", {
+  expect_invisible(plot_bar(iris, alpha = 0.5))
+})
+
+test_that("plot_bar works with both mapped and constant aesthetics", {
+  expect_invisible(plot_bar(iris, fill = Species, alpha = 0.4))
+})
+
+test_that("plot_boxplot works with no aesthetics", {
+  expect_invisible(plot_boxplot(iris, by = "Species"))
+})
+
+test_that("plot_boxplot works with mapped aesthetic (fill)", {
+  expect_invisible(plot_boxplot(iris, by = "Species", fill = Species))
+})
+
+test_that("plot_boxplot works with constant aesthetic (alpha)", {
+  expect_invisible(plot_boxplot(iris, by = "Species", alpha = 0.5))
+})
+
+test_that("plot_boxplot works with both mapped and constant aesthetics", {
+  expect_invisible(plot_boxplot(iris, by = "Species", fill = Species, alpha = 0.3))
+})
+
+test_that("plot_scatterplot works with no aesthetics", {
+  expect_invisible(plot_scatterplot(iris, by = "Species"))
+})
+
+test_that("plot_scatterplot works with mapped aesthetic (fill)", {
+  expect_invisible(plot_scatterplot(iris, by = "Species", fill = Species))
+})
+
+test_that("plot_scatterplot works with constant aesthetic (alpha)", {
+  expect_invisible(plot_scatterplot(iris, by = "Species", alpha = 0.5))
+})
+
+test_that("plot_scatterplot works with both mapped and constant aesthetics", {
+  expect_invisible(plot_scatterplot(iris, by = "Species", fill = Species, alpha = 0.3))
+})
+
+test_that("plot_density works with no aesthetics", {
+  expect_invisible(plot_density(iris))
+})
+
+test_that("plot_density works with mapped aesthetic (fill)", {
+  expect_invisible(plot_density(iris, fill = Species))
+})
+
+test_that("plot_density works with constant aesthetic (size)", {
+  expect_invisible(plot_density(iris, size = 4))
+})
+
+test_that("plot_density works with both mapped and constant aesthetics", {
+  expect_invisible(plot_density(iris, fill = Species, alpha = 0.3, size=4))
+})