diff --git a/R/trace_generation.R b/R/trace_generation.R
index fbba79a436..c3b878f2f7 100644
--- a/R/trace_generation.R
+++ b/R/trace_generation.R
@@ -294,6 +294,11 @@ toBasic <- list(
     g$params$xend <- max(g$prestats.data$globxmax)
     g
   },
+  hline=function(g) {
+    g$params$xstart <- min(g$prestats.data$globxmin)
+    g$params$xend <- max(g$prestats.data$globxmax)
+    g
+  },
   point=function(g) {
     if ("size" %in% names(g$data)) {
       g$params$sizemin <- min(g$prestats.data$globsizemin)
@@ -510,5 +515,13 @@ geom2trace <- list(
          type="scatter",
          mode="lines",
          line=paramORdefault(params, aes2line, line.defaults))
+  },
+  hline=function(data, params) {
+    list(x=c(params$xstart, params$xend),
+         y=c(data$yintercept, data$yintercept),
+         name=params$name,
+         type="scatter",
+         mode="lines",
+         line=paramORdefault(params, aes2line, line.defaults))
   }
 )
diff --git a/tests/testthat/test-ggplot-hline-ggplot2.png b/tests/testthat/test-ggplot-hline-ggplot2.png
new file mode 100644
index 0000000000..30ddddb17f
Binary files /dev/null and b/tests/testthat/test-ggplot-hline-ggplot2.png differ
diff --git a/tests/testthat/test-ggplot-hline-plotly.png b/tests/testthat/test-ggplot-hline-plotly.png
new file mode 100644
index 0000000000..6fee5bfcae
Binary files /dev/null and b/tests/testthat/test-ggplot-hline-plotly.png differ
diff --git a/tests/testthat/test-ggplot-hline.R b/tests/testthat/test-ggplot-hline.R
new file mode 100644
index 0000000000..ff0f135868
--- /dev/null
+++ b/tests/testthat/test-ggplot-hline.R
@@ -0,0 +1,25 @@
+context("Hline")
+
+# Horizontal line
+
+test_that("Second trace be the hline", {
+  
+  x1 <- seq(from=0, to=3.5, by=0.5)
+  x2 <- x1 * 0.95
+  df <- data.frame("x1"=x1, "x2"=x2)
+  
+  gg <- ggplot(df) + geom_point(aes(x=x1, y=x2)) +
+    geom_hline(yintercept=1.1, colour="green", size=3)
+  
+  L <- gg2list(gg)
+  
+  expect_equal(length(L), 3)
+  expect_true(L[[2]]$x[1] <= 0)
+  expect_true(L[[2]]$x[2] >= 3.5)
+  expect_identical(L[[2]]$mode, "lines")
+  expect_identical(L[[2]]$line$shape, "linear")
+  expect_equal(L[[2]]$line$width, 3)
+  expect_identical(L[[2]]$line$color, "rgb(0,255,0)")
+  
+  save_outputs(gg, "hline")
+})
\ No newline at end of file
diff --git a/tests/testthat/test-ggplot-hline.json b/tests/testthat/test-ggplot-hline.json
new file mode 100644
index 0000000000..2a9fae84d2
--- /dev/null
+++ b/tests/testthat/test-ggplot-hline.json
@@ -0,0 +1,98 @@
+{
+    "data": [
+        {
+            "x": [
+                0, 
+                0.5, 
+                1, 
+                1.5, 
+                2, 
+                2.5, 
+                3, 
+                3.5
+            ], 
+            "y": [
+                0, 
+                0.475, 
+                0.95, 
+                1.4249999999999998, 
+                1.9, 
+                2.375, 
+                2.8499999999999996, 
+                3.3249999999999997
+            ], 
+            "mode": "markers", 
+            "marker": {
+                "color": "rgb(0,0,0)", 
+                "size": 10, 
+                "symbol": "circle", 
+                "opacity": 1, 
+                "sizeref": 1, 
+                "sizemode": "area"
+            }, 
+            "xaxis": "x1", 
+            "yaxis": "y1", 
+            "showlegend": false, 
+            "type": "scatter"
+        }, 
+        {
+            "x": [
+                -0.17500000000000002, 
+                3.675
+            ], 
+            "y": [
+                1.1, 
+                1.1
+            ], 
+            "mode": "lines", 
+            "line": {
+                "color": "rgb(0,255,0)", 
+                "width": 3, 
+                "dash": "solid", 
+                "shape": "linear"
+            }, 
+            "xaxis": "x1", 
+            "yaxis": "y1", 
+            "showlegend": false, 
+            "type": "scatter"
+        }
+    ], 
+    "layout": {
+        "titlefont": {
+            "family": ""
+        }, 
+        "showlegend": true, 
+        "xaxis": {
+            "title": "x1", 
+            "type": "linear", 
+            "showgrid": true, 
+            "showline": false, 
+            "showticklabels": true, 
+            "tickcolor": "rgb(127,127,127)", 
+            "gridcolor": "rgb(255,255,255)"
+        }, 
+        "yaxis": {
+            "title": "x2", 
+            "type": "linear", 
+            "showgrid": true, 
+            "showline": false, 
+            "showticklabels": true, 
+            "tickcolor": "rgb(127,127,127)", 
+            "gridcolor": "rgb(255,255,255)"
+        }, 
+        "legend": {
+            "x": 100, 
+            "y": 0.5, 
+            "font": {
+                "family": ""
+            }, 
+            "bgcolor": "rgb(255,255,255)", 
+            "bordercolor": "transparent"
+        }, 
+        "margin": {
+            "r": 10
+        }, 
+        "paper_bgcolor": "rgb(255,255,255)", 
+        "plot_bgcolor": "rgb(229,229,229)"
+    }
+}
diff --git a/tests/testthat/test-ggplot-hline.url b/tests/testthat/test-ggplot-hline.url
new file mode 100644
index 0000000000..0b682abec6
--- /dev/null
+++ b/tests/testthat/test-ggplot-hline.url
@@ -0,0 +1 @@
+https://plot.ly/~TestBot/561
diff --git a/tests/testthat/test-ggplot-theme-marker-default-ggplot2.png b/tests/testthat/test-ggplot-theme-marker-default-ggplot2.png
new file mode 100644
index 0000000000..008a086dd8
Binary files /dev/null and b/tests/testthat/test-ggplot-theme-marker-default-ggplot2.png differ
diff --git a/tests/testthat/test-ggplot-theme-marker-default-plotly.png b/tests/testthat/test-ggplot-theme-marker-default-plotly.png
new file mode 100644
index 0000000000..9ad39ab89d
Binary files /dev/null and b/tests/testthat/test-ggplot-theme-marker-default-plotly.png differ
diff --git a/tests/testthat/test-ggplot-theme-marker-default.json b/tests/testthat/test-ggplot-theme-marker-default.json
new file mode 100644
index 0000000000..b211be567d
--- /dev/null
+++ b/tests/testthat/test-ggplot-theme-marker-default.json
@@ -0,0 +1,123 @@
+{
+    "data": [
+        {
+            "x": [
+                4.2
+            ], 
+            "y": [
+                0.38
+            ], 
+            "mode": "markers", 
+            "name": "Paraguay", 
+            "text": "size: 7", 
+            "marker": {
+                "color": "rgb(248,118,109)", 
+                "size": [
+                    2.5
+                ], 
+                "symbol": "circle", 
+                "line": {
+                    "width": 0
+                }, 
+                "opacity": 1, 
+                "sizeref": 1, 
+                "sizemode": "area"
+            }, 
+            "xaxis": "x1", 
+            "yaxis": "y1", 
+            "type": "scatter"
+        }, 
+        {
+            "x": [
+                1.75
+            ], 
+            "y": [
+                1.67
+            ], 
+            "mode": "markers", 
+            "name": "Peru", 
+            "text": "size: 31", 
+            "marker": {
+                "color": "rgb(0,186,56)", 
+                "size": [
+                    15.26595744680851
+                ], 
+                "symbol": "circle", 
+                "line": {
+                    "width": 0
+                }, 
+                "opacity": 1, 
+                "sizeref": 1, 
+                "sizemode": "area"
+            }, 
+            "xaxis": "x1", 
+            "yaxis": "y1", 
+            "type": "scatter"
+        }, 
+        {
+            "x": [
+                1.33
+            ], 
+            "y": [
+                0.43
+            ], 
+            "mode": "markers", 
+            "name": "Philippines", 
+            "text": "size: 101", 
+            "marker": {
+                "color": "rgb(97,156,255)", 
+                "size": [
+                    52.5
+                ], 
+                "symbol": "circle", 
+                "line": {
+                    "width": 0
+                }, 
+                "opacity": 1, 
+                "sizeref": 1, 
+                "sizemode": "area"
+            }, 
+            "xaxis": "x1", 
+            "yaxis": "y1", 
+            "type": "scatter"
+        }
+    ], 
+    "layout": {
+        "titlefont": {
+            "family": ""
+        }, 
+        "showlegend": true, 
+        "xaxis": {
+            "title": "edu", 
+            "type": "linear", 
+            "showgrid": true, 
+            "showline": false, 
+            "showticklabels": true, 
+            "tickcolor": "rgb(127,127,127)", 
+            "gridcolor": "rgb(255,255,255)"
+        }, 
+        "yaxis": {
+            "title": "illn", 
+            "type": "linear", 
+            "showgrid": true, 
+            "showline": false, 
+            "showticklabels": true, 
+            "tickcolor": "rgb(127,127,127)", 
+            "gridcolor": "rgb(255,255,255)"
+        }, 
+        "legend": {
+            "x": 100, 
+            "y": 0.5, 
+            "font": {
+                "family": ""
+            }, 
+            "bgcolor": "rgb(255,255,255)", 
+            "bordercolor": "transparent"
+        }, 
+        "margin": {
+            "r": 10
+        }, 
+        "paper_bgcolor": "rgb(255,255,255)", 
+        "plot_bgcolor": "rgb(229,229,229)"
+    }
+}
diff --git a/tests/testthat/test-ggplot-theme-marker-default.url b/tests/testthat/test-ggplot-theme-marker-default.url
new file mode 100644
index 0000000000..693e7d463b
--- /dev/null
+++ b/tests/testthat/test-ggplot-theme-marker-default.url
@@ -0,0 +1 @@
+https://plot.ly/~TestBot/559