diff --git a/tests/testthat/_snaps/aes-setting.md b/tests/testthat/_snaps/aes-setting.md
new file mode 100644
index 0000000000..b0ba47a52a
--- /dev/null
+++ b/tests/testthat/_snaps/aes-setting.md
@@ -0,0 +1,36 @@
+# aesthetic parameters match length of data
+
+    Code
+      set_colours(rep("red", 2))
+    Condition
+      Error in `geom_point()`:
+      ! Problem while setting up geom aesthetics.
+      i Error occurred in the 1st layer.
+      Caused by error in `check_aesthetics()`:
+      ! Aesthetics must be either length 1 or the same as the data (5).
+      x Fix the following mappings: `colour`.
+
+---
+
+    Code
+      set_colours(rep("red", 3))
+    Condition
+      Error in `geom_point()`:
+      ! Problem while setting up geom aesthetics.
+      i Error occurred in the 1st layer.
+      Caused by error in `check_aesthetics()`:
+      ! Aesthetics must be either length 1 or the same as the data (5).
+      x Fix the following mappings: `colour`.
+
+---
+
+    Code
+      set_colours(rep("red", 4))
+    Condition
+      Error in `geom_point()`:
+      ! Problem while setting up geom aesthetics.
+      i Error occurred in the 1st layer.
+      Caused by error in `check_aesthetics()`:
+      ! Aesthetics must be either length 1 or the same as the data (5).
+      x Fix the following mappings: `colour`.
+
diff --git a/tests/testthat/_snaps/aes.md b/tests/testthat/_snaps/aes.md
index 7f7f3ddc89..dc1c28889b 100644
--- a/tests/testthat/_snaps/aes.md
+++ b/tests/testthat/_snaps/aes.md
@@ -1,3 +1,14 @@
+# accessing an undefined variable results in an error
+
+    Code
+      get_layer_data(p)
+    Condition
+      Error in `geom_point()`:
+      ! Problem while computing aesthetics.
+      i Error occurred in the 1st layer.
+      Caused by error:
+      ! object 'foo' not found
+
 # aes evaluation fails with unknown input
 
     Unknown input: <environment>
diff --git a/tests/testthat/_snaps/coord-.md b/tests/testthat/_snaps/coord-.md
index c4f74d626c..acf9ad78c6 100644
--- a/tests/testthat/_snaps/coord-.md
+++ b/tests/testthat/_snaps/coord-.md
@@ -18,3 +18,19 @@
 
     `coord()` has not implemented a `range()` method.
 
+# check coord limits errors only on bad inputs
+
+    Code
+      check_coord_limits(xlim(1, 2))
+    Condition
+      Error:
+      ! `xlim(1, 2)` must be a vector of length 2, not a <ScaleContinuousPosition> object.
+
+---
+
+    Code
+      check_coord_limits(1:3)
+    Condition
+      Error:
+      ! `1:3` must be a vector of length 2, not an integer vector of length 3.
+
diff --git a/tests/testthat/_snaps/empty-data.md b/tests/testthat/_snaps/empty-data.md
new file mode 100644
index 0000000000..9889c48a91
--- /dev/null
+++ b/tests/testthat/_snaps/empty-data.md
@@ -0,0 +1,27 @@
+# layers with empty data are silently omitted with facet_wrap
+
+    Code
+      get_layer_data(d)
+    Condition
+      Error in `combine_vars()`:
+      ! Faceting variables must have at least one value.
+
+# layers with empty data are silently omitted with facet_grid
+
+    Code
+      get_layer_data(d)
+    Condition
+      Error in `combine_vars()`:
+      ! Faceting variables must have at least one value.
+
+# Should error when totally empty data frame because there's no x and y
+
+    Code
+      get_layer_data(d)
+    Condition
+      Error in `geom_point()`:
+      ! Problem while computing aesthetics.
+      i Error occurred in the 2nd layer.
+      Caused by error:
+      ! object 'wt' not found
+
diff --git a/tests/testthat/_snaps/facet-.md b/tests/testthat/_snaps/facet-.md
index 2efa86bc64..17d76b1f86 100644
--- a/tests/testthat/_snaps/facet-.md
+++ b/tests/testthat/_snaps/facet-.md
@@ -1,3 +1,19 @@
+# facets reject aes()
+
+    Code
+      facet_wrap(aes(foo))
+    Condition
+      Error in `validate_facets()`:
+      ! Please use `vars()` to supply facet variables.
+
+---
+
+    Code
+      facet_grid(aes(foo))
+    Condition
+      Error in `validate_facets()`:
+      ! Please use `vars()` to supply facet variables.
+
 # facet_grid() fails if passed both a formula and a vars()
 
     `rows` must be `NULL` or a `vars()` list if `cols` is a `vars()` list.
@@ -30,6 +46,14 @@
     x Plot is missing `letter`
     Layer is missing `letter`
 
+# at least one combination must exist in combine_vars()
+
+    Code
+      combine_vars(list(df), vars = vars(letter = letter))
+    Condition
+      Error in `combine_vars()`:
+      ! Faceting variables must have at least one value.
+
 # combine_vars() generates the correct combinations
 
     At least one layer must contain all faceting variables: `b` and `c`
@@ -40,6 +64,15 @@
 
     Faceting variables must have at least one value.
 
+# eval_facet() is tolerant for missing columns (#2963)
+
+    Code
+      eval_facet(quo(no_such_variable * x), data_frame(foo = 1), possible_columns = c(
+        "x"))
+    Condition
+      Error:
+      ! object 'no_such_variable' not found
+
 # validate_facets() provide meaningful errors
 
     Please use `vars()` to supply facet variables.
diff --git a/tests/testthat/_snaps/facet-labels.md b/tests/testthat/_snaps/facet-labels.md
new file mode 100644
index 0000000000..6130705bea
--- /dev/null
+++ b/tests/testthat/_snaps/facet-labels.md
@@ -0,0 +1,16 @@
+# labeller() dispatches labellers
+
+    Code
+      ggplotGrob(p3)
+    Condition
+      Error in `resolve_labeller()`:
+      ! Cannot supply both `rows` and `cols` to `facet_wrap()`.
+
+---
+
+    Code
+      ggplotGrob(p5)
+    Condition
+      Error in `labeller()`:
+      ! Conflict between `.cols` and `cyl`.
+
diff --git a/tests/testthat/_snaps/fortify.md b/tests/testthat/_snaps/fortify.md
index 81c3decea5..2034f092fb 100644
--- a/tests/testthat/_snaps/fortify.md
+++ b/tests/testthat/_snaps/fortify.md
@@ -3,3 +3,153 @@
     `data` must be a <data.frame>, or an object coercible by `fortify()`, or a valid <data.frame>-like object coercible by `as.data.frame()`, not a <uneval> object.
     i Did you accidentally pass `aes()` to the `data` argument?
 
+# fortify.default can handle healthy data-frame-like objects
+
+    Code
+      fortify(X)
+    Condition
+      Error in `fortify()`:
+      ! `data` must be a <data.frame>, or an object coercible by `fortify()`, or a valid <data.frame>-like object coercible by `as.data.frame()`.
+      Caused by error in `.prevalidate_data_frame_like_object()`:
+      ! `dim(data)` must return an <integer> of length 2.
+
+---
+
+    Code
+      fortify(array(1:60, 5:3))
+    Condition
+      Error in `fortify()`:
+      ! `data` must be a <data.frame>, or an object coercible by `fortify()`, or a valid <data.frame>-like object coercible by `as.data.frame()`.
+      Caused by error in `.prevalidate_data_frame_like_object()`:
+      ! `dim(data)` must return an <integer> of length 2.
+
+---
+
+    Code
+      fortify(cbind(X, Y, Z, deparse.level = 0))
+    Condition
+      Error in `fortify()`:
+      ! `data` must be a <data.frame>, or an object coercible by `fortify()`, or a valid <data.frame>-like object coercible by `as.data.frame()`.
+      Caused by error in `.prevalidate_data_frame_like_object()`:
+      ! `colnames(data)` must return a <character> of length `ncol(data)`.
+
+---
+
+    Code
+      fortify(object)
+    Condition
+      Error in `fortify()`:
+      ! `data` must be a <data.frame>, or an object coercible by `fortify()`, or a valid <data.frame>-like object coercible by `as.data.frame()`.
+      Caused by error in `dim.foo()`:
+      ! oops!
+
+---
+
+    Code
+      fortify(object)
+    Condition
+      Error in `fortify()`:
+      ! `data` must be a <data.frame>, or an object coercible by `fortify()`, or a valid <data.frame>-like object coercible by `as.data.frame()`.
+      Caused by error in `.prevalidate_data_frame_like_object()`:
+      ! `dim(data)` must return an <integer> of length 2.
+
+---
+
+    Code
+      fortify(object)
+    Condition
+      Error in `fortify()`:
+      ! `data` must be a <data.frame>, or an object coercible by `fortify()`, or a valid <data.frame>-like object coercible by `as.data.frame()`.
+      Caused by error in `.prevalidate_data_frame_like_object()`:
+      ! `dim(data)` must return an <integer> of length 2.
+
+---
+
+    Code
+      fortify(object)
+    Condition
+      Error in `fortify()`:
+      ! `data` must be a <data.frame>, or an object coercible by `fortify()`, or a valid <data.frame>-like object coercible by `as.data.frame()`.
+      Caused by error in `.prevalidate_data_frame_like_object()`:
+      ! `dim(data)` can't have `NA`s or negative values.
+
+---
+
+    Code
+      fortify(object)
+    Condition
+      Error in `fortify()`:
+      ! `data` must be a <data.frame>, or an object coercible by `fortify()`, or a valid <data.frame>-like object coercible by `as.data.frame()`.
+      Caused by error in `.prevalidate_data_frame_like_object()`:
+      ! `dim(data)` can't have `NA`s or negative values.
+
+---
+
+    Code
+      fortify(object)
+    Condition
+      Error in `fortify()`:
+      ! `data` must be a <data.frame>, or an object coercible by `fortify()`, or a valid <data.frame>-like object coercible by `as.data.frame()`.
+      Caused by error in `dimnames(x)[[2L]]`:
+      ! subscript out of bounds
+
+---
+
+    Code
+      fortify(object)
+    Condition
+      Error in `fortify()`:
+      ! `data` must be a <data.frame>, or an object coercible by `fortify()`, or a valid <data.frame>-like object coercible by `as.data.frame()`.
+      Caused by error in `.prevalidate_data_frame_like_object()`:
+      ! `colnames(data)` must return a <character> of length `ncol(data)`.
+
+---
+
+    Code
+      fortify(object)
+    Condition
+      Error in `fortify()`:
+      ! `data` must be a <data.frame>, or an object coercible by `fortify()`, or a valid <data.frame>-like object coercible by `as.data.frame()`.
+      Caused by error in `.prevalidate_data_frame_like_object()`:
+      ! `colnames(data)` must return a <character> of length `ncol(data)`.
+
+---
+
+    Code
+      fortify(object)
+    Condition
+      Error in `fortify()`:
+      ! `data` must be a <data.frame>, or an object coercible by `fortify()`, or a valid <data.frame>-like object coercible by `as.data.frame()`.
+      Caused by error in `as.data.frame.foo()`:
+      ! oops!
+
+---
+
+    Code
+      fortify(object)
+    Condition
+      Error in `fortify()`:
+      ! `data` must be a <data.frame>, or an object coercible by `fortify()`, or a valid <data.frame>-like object coercible by `as.data.frame()`.
+      Caused by error in `.postvalidate_data_frame_like_object()`:
+      ! `as.data.frame(data)` must return a <data.frame>.
+
+---
+
+    Code
+      fortify(object)
+    Condition
+      Error in `fortify()`:
+      ! `data` must be a <data.frame>, or an object coercible by `fortify()`, or a valid <data.frame>-like object coercible by `as.data.frame()`.
+      Caused by error in `.postvalidate_data_frame_like_object()`:
+      ! `as.data.frame(data)` must preserve dimensions.
+
+---
+
+    Code
+      fortify(object)
+    Condition
+      Error in `fortify()`:
+      ! `data` must be a <data.frame>, or an object coercible by `fortify()`, or a valid <data.frame>-like object coercible by `as.data.frame()`.
+      Caused by error in `.postvalidate_data_frame_like_object()`:
+      ! `as.data.frame(data)` must preserve column names.
+
diff --git a/tests/testthat/_snaps/geom-path.md b/tests/testthat/_snaps/geom-path.md
index 6516134f98..a8819b10de 100644
--- a/tests/testthat/_snaps/geom-path.md
+++ b/tests/testthat/_snaps/geom-path.md
@@ -5,3 +5,11 @@
     Caused by error in `draw_panel()`:
     ! `geom_path()` can't have varying colour, linewidth, and/or alpha along the line when linetype isn't solid.
 
+# stairstep() exists with error when an invalid `direction` is given
+
+    Code
+      stairstep(df, direction = "invalid")
+    Condition
+      Error in `stairstep()`:
+      ! `direction` must be one of "hv", "vh", or "mid", not "invalid".
+
diff --git a/tests/testthat/_snaps/geom-rect.md b/tests/testthat/_snaps/geom-rect.md
new file mode 100644
index 0000000000..8c04cbbb21
--- /dev/null
+++ b/tests/testthat/_snaps/geom-rect.md
@@ -0,0 +1,9 @@
+# geom_rect can derive corners
+
+    Code
+      GeomRect$setup_data(test, NULL)
+    Condition
+      Error in `resolve_rect()`:
+      ! `geom_rect()` requires two of the following aesthetics: xmin, xmax, x, or width.
+      i Currently, x is present.
+
diff --git a/tests/testthat/_snaps/geom-text.md b/tests/testthat/_snaps/geom-text.md
index c9d11b2bc7..ace427b203 100644
--- a/tests/testthat/_snaps/geom-text.md
+++ b/tests/testthat/_snaps/geom-text.md
@@ -3,3 +3,15 @@
     Both `position` and `nudge_x`/`nudge_y` are supplied.
     i Only use one approach to alter the position.
 
+# geom_text() rejects exotic units
+
+    Code
+      ggplotGrob(p + geom_text(size = 10, size.unit = "npc"))
+    Condition
+      Error in `geom_text()`:
+      ! Problem while converting geom to grob.
+      i Error occurred in the 1st layer.
+      Caused by error in `resolve_text_unit()`:
+      ! `unit` must be one of "mm", "pt", "cm", "in", or "pc", not "npc".
+      i Did you mean "pc"?
+
diff --git a/tests/testthat/_snaps/ggsave.md b/tests/testthat/_snaps/ggsave.md
index 8a16fc672b..a1f6ed2b8c 100644
--- a/tests/testthat/_snaps/ggsave.md
+++ b/tests/testthat/_snaps/ggsave.md
@@ -1,7 +1,67 @@
+# ggsave can create directories
+
+    Code
+      ggsave(path, p)
+    Condition
+      Error in `ggsave()`:
+      ! Cannot find directory 'PATH'
+      i Please supply an existing directory or use `create.dir = TRUE`.
+
+# ggsave warns about empty or multiple filenames
+
+    Code
+      ggsave(character(), plot)
+    Condition
+      Error in `ggsave()`:
+      ! `filename` must be a single string, not an empty character vector.
+
+# ggsave fails informatively for no-extension filenames
+
+    Code
+      ggsave(tempfile(), plot)
+    Condition
+      Error in `ggsave()`:
+      ! Can't save to PATH
+      i Either supply `filename` with a file extension or supply `device`.
+
+# warned about large plot unless limitsize = FALSE
+
+    Code
+      plot_dim(c(50, 50))
+    Condition
+      Error:
+      ! Dimensions exceed 50 inches (`height` and `width` are specified in inches not pixels).
+      i If you're sure you want a plot that big, use `limitsize = FALSE`.
+
+---
+
+    Code
+      plot_dim(c(15000, 15000), units = "px")
+    Condition
+      Error:
+      ! Dimensions exceed 50 inches (`height` and `width` are specified in pixels).
+      i If you're sure you want a plot that big, use `limitsize = FALSE`.
+
 # unknown device triggers error
 
     `device` must be a string, function or `NULL`, not the number 1.
 
+---
+
+    Code
+      plot_dev("xyz")
+    Condition
+      Error:
+      ! Unknown graphics device "xyz"
+
+---
+
+    Code
+      plot_dev(NULL, "test.xyz")
+    Condition
+      Error:
+      ! Unknown graphics device "xyz"
+
 # invalid single-string DPI values throw an error
 
     `dpi` must be one of "screen", "print", or "retina", not "abc".
diff --git a/tests/testthat/_snaps/guides.md b/tests/testthat/_snaps/guides.md
index be7c84d7f3..f6dfb10b15 100644
--- a/tests/testthat/_snaps/guides.md
+++ b/tests/testthat/_snaps/guides.md
@@ -63,6 +63,22 @@
     Breaks are not formatted correctly for a bin legend.
     i Use `(<lower>, <upper>]` format to indicate bins.
 
+# get_guide_data retrieves keys appropriately
+
+    Code
+      get_guide_data(b, 1)
+    Condition
+      Error in `get_guide_data()`:
+      ! `aesthetic` must be a single string, not the number 1.
+
+---
+
+    Code
+      get_guide_data(b, "x", panel = "a")
+    Condition
+      Error in `get_guide_data()`:
+      ! `panel` must be a whole number, not the string "a".
+
 # guide_axis_logticks calculates appropriate ticks
 
     The `prescale.base` argument will override the scale's log-10 transformation in log-tick positioning.
diff --git a/tests/testthat/_snaps/labels.md b/tests/testthat/_snaps/labels.md
index 49efe59a72..80b541e2e4 100644
--- a/tests/testthat/_snaps/labels.md
+++ b/tests/testthat/_snaps/labels.md
@@ -25,3 +25,19 @@
 
     `plot.tag.position` must be one of "topleft", "top", "topright", "left", "right", "bottomleft", "bottom", or "bottomright", not "foobar".
 
+---
+
+    Code
+      ggplotGrob(p + theme(plot.tag.position = c(0, 0.5, 1)))
+    Condition
+      Error in `theme()`:
+      ! A <numeric> `plot.tag.position` theme setting must have length 2.
+
+---
+
+    Code
+      ggplotGrob(p + theme(plot.tag.position = c(0, 0), plot.tag.location = "margin"))
+    Condition
+      Error in `theme()`:
+      ! A <numeric> `plot.tag.position` cannot be used with `"margin"` as `plot.tag.location`.
+
diff --git a/tests/testthat/_snaps/layer.md b/tests/testthat/_snaps/layer.md
index d95e11bed6..52f2292552 100644
--- a/tests/testthat/_snaps/layer.md
+++ b/tests/testthat/_snaps/layer.md
@@ -47,6 +47,28 @@
     x `fill = after_stat(data)`
     i Did you map your stat in the wrong layer?
 
+# missing aesthetics trigger informative error
+
+    Code
+      ggplot_build(ggplot(df) + geom_line())
+    Condition
+      Error in `geom_line()`:
+      ! Problem while setting up geom.
+      i Error occurred in the 1st layer.
+      Caused by error in `compute_geom_1()`:
+      ! `geom_line()` requires the following missing aesthetics: x and y.
+
+---
+
+    Code
+      ggplot_build(ggplot(df) + geom_col())
+    Condition
+      Error in `geom_col()`:
+      ! Problem while setting up geom.
+      i Error occurred in the 1st layer.
+      Caused by error in `compute_geom_1()`:
+      ! `geom_col()` requires the following missing aesthetics: x and y.
+
 # function aesthetics are wrapped with after_stat()
 
     Problem while computing aesthetics.
@@ -89,6 +111,16 @@
     All aesthetics have length 1, but the data has 32 rows.
     i Please consider using `annotate()` or provide this layer with data containing a single row.
 
+# layer names can be resolved
+
+    Code
+      p + l + l
+    Condition
+      Error in `new_layer_names()`:
+      ! Names must be unique.
+      x These names are duplicated:
+        * "foobar" at locations 3 and 4.
+
 # layer_data returns a data.frame
 
     `layer_data()` must return a <data.frame>.
diff --git a/tests/testthat/_snaps/performance.md b/tests/testthat/_snaps/performance.md
new file mode 100644
index 0000000000..153fde6c57
--- /dev/null
+++ b/tests/testthat/_snaps/performance.md
@@ -0,0 +1,9 @@
+# modifyList is masked
+
+    Code
+      modifyList(testlist, testappend)
+    Condition
+      Error in `modifyList()`:
+      ! Please use `modify_list()` instead of `modifyList()` for better performance.
+      i See the vignette ggplot2 internal programming guidelines for details.
+
diff --git a/tests/testthat/_snaps/position_dodge.md b/tests/testthat/_snaps/position_dodge.md
new file mode 100644
index 0000000000..044f2b4392
--- /dev/null
+++ b/tests/testthat/_snaps/position_dodge.md
@@ -0,0 +1,11 @@
+# position_dodge warns about missing required aesthetics
+
+    Code
+      ggplot_build(p)
+    Condition
+      Error:
+      ! Problem while computing position.
+      i Error occurred in the 1st layer.
+      Caused by error in `setup_params()`:
+      ! `position_dodge()` requires the following missing aesthetics: x or xmin.
+
diff --git a/tests/testthat/_snaps/scale-discrete.md b/tests/testthat/_snaps/scale-discrete.md
index c668bceba9..a3251c4c4e 100644
--- a/tests/testthat/_snaps/scale-discrete.md
+++ b/tests/testthat/_snaps/scale-discrete.md
@@ -1,3 +1,39 @@
+# Scale is checked in default colour scale
+
+    Code
+      scale_colour_discrete(type = scale_colour_gradient)
+    Condition
+      Error in `scale_colour_discrete()`:
+      ! The `type` argument must return a discrete scale for the colour aesthetic.
+      x The provided scale is continuous.
+
+---
+
+    Code
+      scale_fill_discrete(type = scale_fill_gradient)
+    Condition
+      Error in `scale_fill_discrete()`:
+      ! The `type` argument must return a discrete scale for the fill aesthetic.
+      x The provided scale is continuous.
+
+---
+
+    Code
+      scale_colour_discrete(type = scale_fill_hue)
+    Condition
+      Error in `scale_colour_discrete()`:
+      ! The `type` argument must return a continuous scale for the colour aesthetic.
+      x The provided scale works with the following aesthetics: fill.
+
+---
+
+    Code
+      scale_fill_discrete(type = scale_colour_hue)
+    Condition
+      Error in `scale_fill_discrete()`:
+      ! The `type` argument must return a continuous scale for the fill aesthetic.
+      x The provided scale works with the following aesthetics: colour.
+
 # Aesthetics with no continuous interpretation fails when called
 
     A continuous variable cannot be mapped to the linetype aesthetic.
@@ -8,3 +44,27 @@
     A continuous variable cannot be mapped to the shape aesthetic.
     i Choose a different aesthetic or use `scale_shape_binned()`.
 
+# mapped_discrete vectors behaves as predicted
+
+    Code
+      mapped_discrete(letters)
+    Condition
+      Error in `mapped_discrete()`:
+      ! Can't convert `x` <character> to <double>.
+
+# invalid palettes trigger errors
+
+    Code
+      ggplot_build(p + scale_x_discrete(palette = function(x) LETTERS[1:3]))
+    Condition
+      Error in `scale_x_discrete()`:
+      ! The `palette` function must return a <numeric> vector.
+
+---
+
+    Code
+      ggplot_build(p + scale_x_discrete(palette = function(x) 1:2))
+    Condition
+      Error in `scale_x_discrete()`:
+      ! The `palette` function must return at least 3 values.
+
diff --git a/tests/testthat/_snaps/scale-manual.md b/tests/testthat/_snaps/scale-manual.md
index faf69a7899..70c2fa4dfd 100644
--- a/tests/testthat/_snaps/scale-manual.md
+++ b/tests/testthat/_snaps/scale-manual.md
@@ -2,3 +2,19 @@
 
     No shared levels found between `names(values)` of the manual scale and the data's colour values.
 
+# insufficient values raise an error
+
+    Code
+      ggplot_build(p + scale_colour_manual(values = "black"))
+    Condition
+      Error in `palette()`:
+      ! Insufficient values in manual scale. 2 needed but only 1 provided.
+
+# fewer values (#3451)
+
+    Code
+      s2$map(c("4", "6", "8"))
+    Condition
+      Error in `palette()`:
+      ! Insufficient values in manual scale. 3 needed but only 2 provided.
+
diff --git a/tests/testthat/_snaps/scales-breaks-labels.md b/tests/testthat/_snaps/scales-breaks-labels.md
new file mode 100644
index 0000000000..fb6b6e8a86
--- /dev/null
+++ b/tests/testthat/_snaps/scales-breaks-labels.md
@@ -0,0 +1,128 @@
+# labels match breaks
+
+    Code
+      scale_x_discrete(breaks = 1:3, labels = 1:2)
+    Condition
+      Error in `scale_x_discrete()`:
+      ! `breaks` and `labels` must have the same length.
+
+---
+
+    Code
+      scale_x_continuous(breaks = 1:3, labels = 1:2)
+    Condition
+      Error in `scale_x_continuous()`:
+      ! `breaks` and `labels` must have the same length.
+
+# suppressing breaks, minor_breask, and labels works
+
+    Code
+      scale_x_date(breaks = NA, limits = lims)$get_breaks()
+    Condition
+      Error in `scale_x_date()`:
+      ! Invalid `breaks` specification. Use `NULL`, not `NA`.
+
+---
+
+    Code
+      scale_x_date(labels = NA, limits = lims)$get_labels()
+    Condition
+      Error in `scale_x_date()`:
+      ! Invalid `labels` specification. Use `NULL`, not `NA`.
+
+---
+
+    Code
+      scale_x_date(minor_breaks = NA, limits = lims)$get_breaks_minor()
+    Condition
+      Error in `scale_x_date()`:
+      ! Invalid `minor_breaks` specification. Use `NULL`, not `NA`.
+
+---
+
+    Code
+      scale_x_datetime(breaks = NA, limits = lims)$get_breaks()
+    Condition
+      Error in `scale_x_datetime()`:
+      ! Invalid `breaks` specification. Use `NULL`, not `NA`.
+
+---
+
+    Code
+      scale_x_datetime(labels = NA, limits = lims)$get_labels()
+    Condition
+      Error in `scale_x_datetime()`:
+      ! Invalid `labels` specification. Use `NULL`, not `NA`.
+
+---
+
+    Code
+      scale_x_datetime(minor_breaks = NA, limits = lims)$get_breaks_minor()
+    Condition
+      Error in `scale_x_datetime()`:
+      ! Invalid `minor_breaks` specification. Use `NULL`, not `NA`.
+
+# scale_breaks with explicit NA options (deprecated)
+
+    Code
+      sxc$get_breaks()
+    Condition
+      Error in `scale_x_continuous()`:
+      ! Invalid `breaks` specification. Use `NULL`, not `NA`.
+
+---
+
+    Code
+      sxc$get_breaks_minor()
+    Condition
+      Error in `scale_x_continuous()`:
+      ! Invalid `breaks` specification. Use `NULL`, not `NA`.
+
+---
+
+    Code
+      syc$get_breaks()
+    Condition
+      Error in `scale_y_continuous()`:
+      ! Invalid `breaks` specification. Use `NULL`, not `NA`.
+
+---
+
+    Code
+      syc$get_breaks_minor()
+    Condition
+      Error in `scale_y_continuous()`:
+      ! Invalid `breaks` specification. Use `NULL`, not `NA`.
+
+---
+
+    Code
+      sac$get_breaks()
+    Condition
+      Error in `scale_alpha_continuous()`:
+      ! Invalid `breaks` specification. Use `NULL`, not `NA`.
+
+---
+
+    Code
+      ssc$get_breaks()
+    Condition
+      Error in `scale_size_continuous()`:
+      ! Invalid `breaks` specification. Use `NULL`, not `NA`.
+
+---
+
+    Code
+      sfc$get_breaks()
+    Condition
+      Error in `scale_fill_continuous()`:
+      ! Invalid `breaks` specification. Use `NULL`, not `NA`.
+
+---
+
+    Code
+      scc$get_breaks()
+    Condition
+      Error in `scale_colour_continuous()`:
+      ! Invalid `breaks` specification. Use `NULL`, not `NA`.
+
diff --git a/tests/testthat/_snaps/stat-bin.md b/tests/testthat/_snaps/stat-bin.md
index dd7a8127bf..f92e737d94 100644
--- a/tests/testthat/_snaps/stat-bin.md
+++ b/tests/testthat/_snaps/stat-bin.md
@@ -53,6 +53,26 @@
     Caused by error in `bin_breaks_bins()`:
     ! `bins` must be a whole number larger than or equal to 1, not the number -4.
 
+# setting boundary and center
+
+    Code
+      comp_bin(df, boundary = 5, center = 0)
+    Condition
+      Error in `stat_bin()`:
+      ! Problem while computing stat.
+      i Error occurred in the 1st layer.
+      Caused by error in `setup_params()`:
+      ! Only one of `boundary` and `center` may be specified in `stat_bin()`.
+
+# bin errors at high bin counts
+
+    Code
+      bin_breaks_width(c(1, 2e+06), 1)
+    Condition
+      Error in `bin_breaks_width()`:
+      ! The number of histogram bins must be less than 1,000,000.
+      i Did you make `binwidth` too small?
+
 # stat_count throws error when both x and y aesthetic present
 
     Problem while computing stat.
diff --git a/tests/testthat/_snaps/stat-ecdf.md b/tests/testthat/_snaps/stat-ecdf.md
index e4da4c47f9..ea9888a2aa 100644
--- a/tests/testthat/_snaps/stat-ecdf.md
+++ b/tests/testthat/_snaps/stat-ecdf.md
@@ -5,3 +5,11 @@
     Caused by error in `setup_params()`:
     ! `stat_ecdf()` requires an x or y aesthetic.
 
+# weighted ecdf warns about weird weights
+
+    Code
+      wecdf(1:10, rep(c(-1, 1), 5))
+    Condition
+      Error in `wecdf()`:
+      ! Cannot compute eCDF when the weight aesthetic sums up to "0".
+
diff --git a/tests/testthat/_snaps/stats.md b/tests/testthat/_snaps/stats.md
index 92a4296185..bde26ba7d0 100644
--- a/tests/testthat/_snaps/stats.md
+++ b/tests/testthat/_snaps/stats.md
@@ -1,3 +1,14 @@
+# error message is thrown when aesthetics are missing
+
+    Code
+      ggplot_build(p)
+    Condition
+      Error in `stat_sum()`:
+      ! Problem while computing stat.
+      i Error occurred in the 1st layer.
+      Caused by error in `compute_layer()`:
+      ! `stat_sum()` requires the following missing aesthetics: x and y.
+
 # erroneously dropped aesthetics are found and issue a warning
 
     The following aesthetics were dropped during statistical transformation: colour and fill.
diff --git a/tests/testthat/_snaps/theme.md b/tests/testthat/_snaps/theme.md
index 259a887c1a..fa7237d37d 100644
--- a/tests/testthat/_snaps/theme.md
+++ b/tests/testthat/_snaps/theme.md
@@ -1,3 +1,19 @@
+# modifying theme element properties with + operator works
+
+    Code
+      theme_grey() + "asdf"
+    Condition
+      Error:
+      ! Can't add `"asdf"` to a theme object.
+
+# replacing theme elements with %+replace% operator works
+
+    Code
+      theme_grey() + "asdf"
+    Condition
+      Error:
+      ! Can't add `"asdf"` to a theme object.
+
 # theme validation happens at build stage
 
     The `text` theme element must be a <element_text> object.
@@ -40,6 +56,14 @@
 
     The `blablabla` theme element must be a <element_text> object.
 
+# elements can be merged
+
+    Code
+      merge_element(text_base, rect_base)
+    Condition
+      Error in `merge_element()`:
+      ! Only elements of the same class can be merged.
+
 # Theme elements are checked during build
 
     `plot.title.position` must be one of "panel" or "plot", not "test".
diff --git a/tests/testthat/test-aes-setting.R b/tests/testthat/test-aes-setting.R
index 422032017f..2071921c03 100644
--- a/tests/testthat/test-aes-setting.R
+++ b/tests/testthat/test-aes-setting.R
@@ -7,9 +7,9 @@ test_that("aesthetic parameters match length of data", {
   }
 
   set_colours("red")
-  expect_error(set_colours(rep("red", 2)), "must be either length 1")
-  expect_error(set_colours(rep("red", 3)), "must be either length 1")
-  expect_error(set_colours(rep("red", 4)), "must be either length 1")
+  expect_snapshot(set_colours(rep("red", 2)), error = TRUE)
+  expect_snapshot(set_colours(rep("red", 3)), error = TRUE)
+  expect_snapshot(set_colours(rep("red", 4)), error = TRUE)
   set_colours(rep("red", 5))
 })
 
@@ -31,7 +31,7 @@ test_that("legend filters out aesthetics not of length 1", {
 
   # Ideally would test something in the legend data structure, but
   # that's not easily accessible currently.
-  expect_error(ggplot_gtable(ggplot_build(p)), NA)
+  expect_no_error(ggplot_gtable(ggplot_build(p)))
 })
 
 test_that("alpha affects only fill colour of solid geoms", {
diff --git a/tests/testthat/test-aes.R b/tests/testthat/test-aes.R
index 1cb333fcac..dd4f742f16 100644
--- a/tests/testthat/test-aes.R
+++ b/tests/testthat/test-aes.R
@@ -48,8 +48,10 @@ test_that("aes evaluated in environment where plot created", {
   df <- data_frame(x = 1, y = 1)
   p <- ggplot(df, aes(foo, y)) + geom_point()
 
-  # Accessing an undefined variable should result in error
-  expect_error(get_layer_data(p), "'foo' not found")
+  test_that("accessing an undefined variable results in an error", {
+    skip_if(getRversion() <= "4.4.0")
+    expect_snapshot(get_layer_data(p), error = TRUE)
+  })
 
   # Once it's defined we should get it back
   foo <- 0
diff --git a/tests/testthat/test-coord-.R b/tests/testthat/test-coord-.R
index f1e910c807..b0cef2de26 100644
--- a/tests/testthat/test-coord-.R
+++ b/tests/testthat/test-coord-.R
@@ -47,10 +47,10 @@ test_that("check coord limits errors only on bad inputs", {
   expect_null(check_coord_limits(c(1,2)))
 
   # Should raise error if Scale object is passed
-  expect_error(check_coord_limits(xlim(1,2)))
+  expect_snapshot(check_coord_limits(xlim(1,2)), error = TRUE)
 
   # Should raise error if vector of wrong length is passed
-  expect_error(check_coord_limits(1:3))
+  expect_snapshot(check_coord_limits(1:3), error = TRUE)
 })
 
 test_that("coords append a column to the layout correctly", {
diff --git a/tests/testthat/test-empty-data.R b/tests/testthat/test-empty-data.R
index bdcc02003c..e6fe24ce38 100644
--- a/tests/testthat/test-empty-data.R
+++ b/tests/testthat/test-empty-data.R
@@ -34,7 +34,7 @@ test_that("layers with empty data are silently omitted with facet_wrap", {
   d <- ggplot(df0, aes(mpg, wt)) +
     geom_point() +
     facet_wrap(~cyl)
-  expect_error(get_layer_data(d), "must have at least one value")
+  expect_snapshot(get_layer_data(d), error = TRUE)
 
   d <- d + geom_point(data = mtcars)
   expect_equal(nrow(get_layer_data(d, 1)), 0)
@@ -45,7 +45,7 @@ test_that("layers with empty data are silently omitted with facet_grid", {
   d <- ggplot(df0, aes(mpg, wt)) +
     geom_point() +
     facet_grid(am ~ cyl)
-  expect_error(get_layer_data(d), "must have at least one value")
+  expect_snapshot(get_layer_data(d), error = TRUE)
 
   d <- d + geom_point(data = mtcars)
   expect_equal(nrow(get_layer_data(d, 1)), 0)
@@ -53,11 +53,13 @@ test_that("layers with empty data are silently omitted with facet_grid", {
 })
 
 test_that("empty data overrides plot defaults", {
-  # Should error when totally empty data frame because there's no x and y
-  d <- ggplot(mtcars, aes(mpg, wt)) +
-    geom_point() +
-    geom_point(data = data_frame())
-  expect_error(get_layer_data(d), "not found")
+  test_that("Should error when totally empty data frame because there's no x and y", {
+    skip_if(getRversion() <= "4.4.0")
+    d <- ggplot(mtcars, aes(mpg, wt)) +
+      geom_point() +
+      geom_point(data = data_frame())
+    expect_snapshot(get_layer_data(d), error = TRUE)
+  })
 
   # No extra points when x and y vars don't exist but are set
   d <- ggplot(mtcars, aes(mpg, wt)) +
diff --git a/tests/testthat/test-facet-.R b/tests/testthat/test-facet-.R
index 5084737622..11e86247ca 100644
--- a/tests/testthat/test-facet-.R
+++ b/tests/testthat/test-facet-.R
@@ -43,8 +43,8 @@ test_that("as_facets_list() coerces quosures objectss", {
 })
 
 test_that("facets reject aes()", {
-  expect_error(facet_wrap(aes(foo)), "Please use `vars()` to supply facet variables", fixed = TRUE)
-  expect_error(facet_grid(aes(foo)), "Please use `vars()` to supply facet variables", fixed = TRUE)
+  expect_snapshot(facet_wrap(aes(foo)), error = TRUE)
+  expect_snapshot(facet_grid(aes(foo)), error = TRUE)
 })
 
 test_that("compact_facets() returns a quosures object with compacted", {
@@ -353,9 +353,9 @@ test_that("at least one layer must contain all facet variables in combine_vars()
 
 test_that("at least one combination must exist in combine_vars()", {
   df <- data_frame(letter = character(0))
-  expect_error(
+  expect_snapshot(
     combine_vars(list(df), vars = vars(letter = letter)),
-    "Faceting variables must have at least one value"
+    error = TRUE
   )
 })
 
@@ -463,9 +463,9 @@ test_that("eval_facet() is tolerant for missing columns (#2963)", {
   )
 
   # If the expression contains any non-existent variable, it fails
-  expect_error(
+  expect_snapshot(
     eval_facet(quo(no_such_variable * x), data_frame(foo = 1), possible_columns = c("x")),
-    "object 'no_such_variable' not found"
+    error = TRUE
   )
 })
 
diff --git a/tests/testthat/test-facet-labels.R b/tests/testthat/test-facet-labels.R
index c8613bc978..dfe39fe7cf 100644
--- a/tests/testthat/test-facet-labels.R
+++ b/tests/testthat/test-facet-labels.R
@@ -86,7 +86,7 @@ test_that("labeller() dispatches labellers", {
   # facet_wrap() shouldn't get both rows and cols
   p3 <- p + facet_wrap(~cyl, labeller = labeller(
     .cols = label_both, .rows = label_both))
-  expect_error(ggplotGrob(p3))
+  expect_snapshot(ggplotGrob(p3), error = TRUE)
 
   # facet_grid() can get both rows and cols
   p4 <- p + facet_grid(am ~ cyl, labeller = labeller(
@@ -98,7 +98,7 @@ test_that("labeller() dispatches labellers", {
   # margin-wide labeller
   p5 <- p + facet_wrap(~cyl, labeller = labeller(
     .rows = label_both, cyl = label_value))
-  expect_error(ggplotGrob(p5))
+  expect_snapshot(ggplotGrob(p5), error = TRUE)
 
   # Variables can be attributed labellers
   p6 <- p + facet_grid(am + cyl ~ ., labeller = labeller(
diff --git a/tests/testthat/test-fortify.R b/tests/testthat/test-fortify.R
index 3a48c76ba0..e98edad549 100644
--- a/tests/testthat/test-fortify.R
+++ b/tests/testthat/test-fortify.R
@@ -67,12 +67,12 @@ test_that("fortify.default can handle healthy data-frame-like objects", {
 
   # Not even data-frame-like
 
-  expect_error(fortify(X))
-  expect_error(fortify(array(1:60, 5:3)))
+  expect_snapshot(fortify(X), error = TRUE)
+  expect_snapshot(fortify(array(1:60, 5:3)), error = TRUE)
 
   # Unhealthy data-frame-like (matrix with no colnames)
 
-  expect_error(fortify(cbind(X, Y, Z, deparse.level=0)))
+  expect_snapshot(fortify(cbind(X, Y, Z, deparse.level=0)), error = TRUE)
 
   # Healthy data-frame-like (matrix with colnames)
 
@@ -100,25 +100,27 @@ test_that("fortify.default can handle healthy data-frame-like objects", {
 
   # Rejected by fortify.default() because of unhealthy dim() behavior
 
+  skip_if(getRversion() <= "4.4.0")
+
   dim.foo <- function(x) stop("oops!")
   registerS3method("dim", "foo", dim.foo)
-  expect_error(fortify(object))
+  expect_snapshot(fortify(object), error = TRUE)
 
   dim.foo <- function(x) c(length(x), 2)
   registerS3method("dim", "foo", dim.foo)
-  expect_error(fortify(object))
+  expect_snapshot(fortify(object), error = TRUE)
 
   dim.foo <- function(x) 5:2
   registerS3method("dim", "foo", dim.foo)
-  expect_error(fortify(object))
+  expect_snapshot(fortify(object), error = TRUE)
 
   dim.foo <- function(x) c(length(x), NA_integer_)
   registerS3method("dim", "foo", dim.foo)
-  expect_error(fortify(object))
+  expect_snapshot(fortify(object), error = TRUE)
 
   dim.foo <- function(x) c(length(x), -5L)
   registerS3method("dim", "foo", dim.foo)
-  expect_error(fortify(object))
+  expect_snapshot(fortify(object), error = TRUE)
 
   # Repair dim(<foo>)
 
@@ -129,18 +131,18 @@ test_that("fortify.default can handle healthy data-frame-like objects", {
 
   dimnames.foo <- function(x) list()  # this breaks colnames(<foo>)
   registerS3method("dimnames", "foo", dimnames.foo)
-  expect_error(fortify(object))
+  expect_snapshot(fortify(object), error = TRUE)
 
   dimnames.foo <- function(x) list(format(seq_along(x)), toupper)
   registerS3method("dimnames", "foo", dimnames.foo)
-  expect_error(fortify(object))
+  expect_snapshot(fortify(object), error = TRUE)
 
   # Rejected by fortify.default() because behaviors of dim() and colnames()
   # don't align
 
   dimnames.foo <- function(x) list(NULL, c("X1", "X2", "X3"))
   registerS3method("dimnames", "foo", dimnames.foo)
-  expect_error(fortify(object))
+  expect_snapshot(fortify(object), error = TRUE)
 
   # Repair colnames(<foo>)
 
@@ -151,20 +153,21 @@ test_that("fortify.default can handle healthy data-frame-like objects", {
 
   as.data.frame.foo <- function(x, row.names = NULL, ...) stop("oops!")
   registerS3method("as.data.frame", "foo", as.data.frame.foo)
-  expect_error(fortify(object))
+  expect_snapshot(fortify(object), error = TRUE)
 
   as.data.frame.foo <- function(x, row.names = NULL, ...) "whatever"
   registerS3method("as.data.frame", "foo", as.data.frame.foo)
-  expect_error(fortify(object))
+  expect_snapshot(fortify(object), error = TRUE)
 
   as.data.frame.foo <- function(x, row.names = NULL, ...) data.frame()
   registerS3method("as.data.frame", "foo", as.data.frame.foo)
-  expect_error(fortify(object))
+
+  expect_snapshot(fortify(object), error = TRUE)
 
   as.data.frame.foo <- function(x, row.names = NULL, ...) {
     key <- if (is.null(names(x))) rownames(x) else names(x)
     data.frame(oops=key, value=unname(unclass(x)))
   }
   registerS3method("as.data.frame", "foo", as.data.frame.foo)
-  expect_error(fortify(object))
+  expect_snapshot(fortify(object), error = TRUE)
 })
diff --git a/tests/testthat/test-geom-path.R b/tests/testthat/test-geom-path.R
index 3255a2f4cb..cb3128931e 100644
--- a/tests/testthat/test-geom-path.R
+++ b/tests/testthat/test-geom-path.R
@@ -35,7 +35,7 @@ test_that("stairstep() does not error with too few observations", {
 
 test_that("stairstep() exists with error when an invalid `direction` is given", {
   df <- data_frame(x = 1:3, y = 1:3)
-  expect_error(stairstep(df, direction="invalid"))
+  expect_snapshot(stairstep(df, direction = "invalid"), error = TRUE)
 })
 
 test_that("stairstep() output is correct for direction = 'vh'", {
diff --git a/tests/testthat/test-geom-rect.R b/tests/testthat/test-geom-rect.R
index a0d90899f8..204df65ef2 100644
--- a/tests/testthat/test-geom-rect.R
+++ b/tests/testthat/test-geom-rect.R
@@ -29,8 +29,5 @@ test_that("geom_rect can derive corners", {
   expect_equal(full[, corners], test[, corners])
 
   test <- full[, c("x", "y")]
-  expect_error(
-    GeomRect$setup_data(test, NULL),
-    "requires two of the following aesthetics"
-  )
+  expect_snapshot(GeomRect$setup_data(test, NULL), error = TRUE)
 })
diff --git a/tests/testthat/test-geom-sf.R b/tests/testthat/test-geom-sf.R
index e52a13e917..beb1e3b86a 100644
--- a/tests/testthat/test-geom-sf.R
+++ b/tests/testthat/test-geom-sf.R
@@ -177,7 +177,7 @@ test_that("geom_sf draws correctly", {
   # Perform minimal tests
   pts <- sf::st_sf(a = 1:2, geometry = sf::st_sfc(sf::st_point(0:1), sf::st_point(1:2)))
   plot <- ggplot() + geom_sf(data = pts)
-  expect_error(regexp = NA, ggplot_build(plot))
+  expect_no_error(ggplot_build(plot))
 
   expect_doppelganger("North Carolina county boundaries",
     ggplot() + geom_sf(data = nc) + coord_sf(datum = 4326)
diff --git a/tests/testthat/test-geom-text.R b/tests/testthat/test-geom-text.R
index ca5b495968..79220d2cf2 100644
--- a/tests/testthat/test-geom-text.R
+++ b/tests/testthat/test-geom-text.R
@@ -30,9 +30,9 @@ test_that("geom_text() accepts mm and pt size units", {
 
 test_that("geom_text() rejects exotic units", {
   p <- ggplot(data_frame0(x = 1, y = 1, label = "A"), aes(x, y, label = label))
-  expect_error(
+  expect_snapshot(
     ggplotGrob(p + geom_text(size = 10, size.unit = "npc")),
-    "must be one of"
+    error = TRUE
   )
 })
 
diff --git a/tests/testthat/test-ggsave.R b/tests/testthat/test-ggsave.R
index a5d7a5283c..dbbc890ca5 100644
--- a/tests/testthat/test-ggsave.R
+++ b/tests/testthat/test-ggsave.R
@@ -16,7 +16,10 @@ test_that("ggsave can create directories", {
 
   p <- ggplot(mpg, aes(displ, hwy)) + geom_point()
 
-  expect_error(ggsave(path, p))
+  expect_snapshot(
+    ggsave(path, p), error = TRUE,
+    transform = function(x) gsub("directory '.*'\\.$", "directory 'PATH'", x)
+  )
   expect_false(dir.exists(dirname(path)))
 
   # 2 messages: 1 for saving and 1 informing about directory creation
@@ -83,17 +86,14 @@ test_that("ggsave warns about empty or multiple filenames", {
     )
   })
 
-  expect_error(
-    ggsave(character(), plot),
-    "`filename` must be a single string"
-  )
+  expect_snapshot(ggsave(character(), plot), error = TRUE)
 })
 
 test_that("ggsave fails informatively for no-extension filenames", {
   plot <- ggplot(mtcars, aes(disp, mpg)) + geom_point()
-  expect_error(
-    ggsave(tempfile(), plot),
-    "Can't save to"
+  expect_snapshot(
+    ggsave(tempfile(), plot), error = TRUE,
+    transform = function(x) gsub("to .*\\.$", "to PATH", x)
   )
 })
 
@@ -112,9 +112,9 @@ test_that("uses 7x7 if no graphics device open", {
 })
 
 test_that("warned about large plot unless limitsize = FALSE", {
-  expect_error(plot_dim(c(50, 50)), "exceed 50 inches")
+  expect_snapshot(plot_dim(c(50, 50)), error = TRUE)
   expect_equal(plot_dim(c(50, 50), limitsize = FALSE), c(50, 50))
-  expect_error(plot_dim(c(15000, 15000), units = "px"), "in pixels).")
+  expect_snapshot(plot_dim(c(15000, 15000), units = "px"), error = TRUE)
 })
 
 test_that("scale multiplies height & width", {
@@ -126,8 +126,8 @@ test_that("scale multiplies height & width", {
 
 test_that("unknown device triggers error", {
   expect_snapshot_error(plot_dev(1))
-  expect_error(plot_dev("xyz"), "Unknown graphics device")
-  expect_error(plot_dev(NULL, "test.xyz"), "Unknown graphics device")
+  expect_snapshot(plot_dev("xyz"), error = TRUE)
+  expect_snapshot(plot_dev(NULL, "test.xyz"), error = TRUE)
 })
 
 
diff --git a/tests/testthat/test-guides.R b/tests/testthat/test-guides.R
index 23df1f75e2..eb1b936350 100644
--- a/tests/testthat/test-guides.R
+++ b/tests/testthat/test-guides.R
@@ -381,8 +381,8 @@ test_that("get_guide_data retrieves keys appropriately", {
   # Non-existent panels
   expect_null(get_guide_data(b, "x", panel = 4))
 
-  expect_error(get_guide_data(b, 1), "must be a single string")
-  expect_error(get_guide_data(b, "x", panel = "a"), "must be a whole number")
+  expect_snapshot(get_guide_data(b, 1), error = TRUE)
+  expect_snapshot(get_guide_data(b, "x", panel = "a"), error = TRUE)
 })
 
 test_that("get_guide_data retrieves keys from exotic coords", {
diff --git a/tests/testthat/test-labels.R b/tests/testthat/test-labels.R
index 6a26578c0b..b8b002a3db 100644
--- a/tests/testthat/test-labels.R
+++ b/tests/testthat/test-labels.R
@@ -116,13 +116,13 @@ test_that("plot.tag.position rejects invalid input", {
   expect_snapshot_error(
     ggplotGrob(p + theme(plot.tag.position = "foobar"))
   )
-  expect_error(
+  expect_snapshot(
     ggplotGrob(p + theme(plot.tag.position = c(0, 0.5, 1))),
-    "must have length 2"
+    error = TRUE
   )
-  expect_error(
+  expect_snapshot(
     ggplotGrob(p + theme(plot.tag.position = c(0, 0), plot.tag.location = "margin")),
-    "cannot be used with `\"margin\""
+    error = TRUE
   )
 
 })
diff --git a/tests/testthat/test-layer.R b/tests/testthat/test-layer.R
index 51f0cd9eee..b7023d342f 100644
--- a/tests/testthat/test-layer.R
+++ b/tests/testthat/test-layer.R
@@ -55,13 +55,13 @@ test_that("column vectors are allowed (#2609)", {
 
 test_that("missing aesthetics trigger informative error", {
   df <- data_frame(x = 1:10)
-  expect_error(
+  expect_snapshot(
     ggplot_build(ggplot(df) + geom_line()),
-    "requires the following missing aesthetics:"
+    error = TRUE
   )
-  expect_error(
+  expect_snapshot(
     ggplot_build(ggplot(df) + geom_col()),
-    "requires the following missing aesthetics:"
+    error = TRUE
   )
 })
 
@@ -154,10 +154,7 @@ test_that("layer names can be resolved", {
   expect_equal(names(p$layers), c("foo", "bar"))
 
   l <- geom_point(name = "foobar")
-  expect_error(
-    p + l + l,
-    "names are duplicated"
-  )
+  expect_snapshot(p + l + l, error = TRUE)
 })
 
 
diff --git a/tests/testthat/test-performance.R b/tests/testthat/test-performance.R
index 1c65622b4a..bd737f7c26 100644
--- a/tests/testthat/test-performance.R
+++ b/tests/testthat/test-performance.R
@@ -12,7 +12,7 @@ testappend <- list(
 )
 
 test_that("modifyList is masked", {
-  expect_error(modifyList(testlist, testappend))
+  expect_snapshot(modifyList(testlist, testappend), error = TRUE)
 })
 
 test_that("modify_list retains unreferenced elements", {
diff --git a/tests/testthat/test-position_dodge.R b/tests/testthat/test-position_dodge.R
index 9107de1d92..14b79d3cad 100644
--- a/tests/testthat/test-position_dodge.R
+++ b/tests/testthat/test-position_dodge.R
@@ -51,5 +51,5 @@ test_that("position_dodge warns about missing required aesthetics", {
       mapping = aes(x = NULL)
     )
 
-  expect_error(ggplot_build(p), "requires the following missing aesthetics")
+  expect_snapshot(ggplot_build(p), error = TRUE)
 })
diff --git a/tests/testthat/test-qplot.R b/tests/testthat/test-qplot.R
index 58e8fa1e14..74ab153c39 100644
--- a/tests/testthat/test-qplot.R
+++ b/tests/testthat/test-qplot.R
@@ -46,7 +46,7 @@ test_that("qplot() evaluates layers in package environment", {
   }
 
   lifecycle::expect_deprecated(
-    expect_error(p <- qplot(1, 1, geom = "line"), NA)
+    expect_no_error(p <- qplot(1, 1, geom = "line"))
   )
 })
 
diff --git a/tests/testthat/test-scale-discrete.R b/tests/testthat/test-scale-discrete.R
index 9e8eeaf717..50f7b585fe 100644
--- a/tests/testthat/test-scale-discrete.R
+++ b/tests/testthat/test-scale-discrete.R
@@ -134,12 +134,12 @@ test_that("discrete scale defaults can be set globally", {
 
 test_that("Scale is checked in default colour scale", {
   # Check scale type
-  expect_error(scale_colour_discrete(type = scale_colour_gradient))
-  expect_error(scale_fill_discrete(type = scale_fill_gradient))
+  expect_snapshot(scale_colour_discrete(type = scale_colour_gradient), error = TRUE)
+  expect_snapshot(scale_fill_discrete(type = scale_fill_gradient), error = TRUE)
 
   # Check aesthetic
-  expect_error(scale_colour_discrete(type = scale_fill_hue))
-  expect_error(scale_fill_discrete(type = scale_colour_hue))
+  expect_snapshot(scale_colour_discrete(type = scale_fill_hue), error = TRUE)
+  expect_snapshot(scale_fill_discrete(type = scale_colour_hue), error = TRUE)
 })
 
 test_that("Aesthetics with no continuous interpretation fails when called", {
@@ -153,7 +153,7 @@ test_that("mapped_discrete vectors behaves as predicted", {
   expect_null(mapped_discrete(NULL))
   expect_s3_class(mapped_discrete(c(0, 3.5)), "mapped_discrete")
   expect_s3_class(mapped_discrete(seq_len(4)), "mapped_discrete")
-  expect_error(mapped_discrete(letters))
+  expect_snapshot(mapped_discrete(letters), error = TRUE)
 
   x <- mapped_discrete(1:10)
   expect_s3_class(x[2:4], "mapped_discrete")
@@ -192,14 +192,14 @@ test_that("invalid palettes trigger errors", {
   p <- ggplot(df, aes(x, y)) +
     geom_point()
 
-  expect_error(
+  expect_snapshot(
     ggplot_build(p + scale_x_discrete(palette = function(x) LETTERS[1:3])),
-    "must return a .+ vector\\."
+    error = TRUE
   )
 
-  expect_error(
+  expect_snapshot(
     ggplot_build(p + scale_x_discrete(palette = function(x) 1:2)),
-    "must return at least 3 values"
+    error = TRUE
   )
 })
 
diff --git a/tests/testthat/test-scale-manual.R b/tests/testthat/test-scale-manual.R
index 2ad47425f7..324485952b 100644
--- a/tests/testthat/test-scale-manual.R
+++ b/tests/testthat/test-scale-manual.R
@@ -54,8 +54,7 @@ test_that("insufficient values raise an error", {
   df <- data_frame(x = 1, y = 1:3, z = factor(c(1:2, NA), exclude = NULL))
   p <- ggplot(df, aes(x, y, colour = z)) + geom_point()
 
-  expect_error(ggplot_build(p + scale_colour_manual(values = "black")),
-    "Insufficient values")
+  expect_snapshot(ggplot_build(p + scale_colour_manual(values = "black")), error = TRUE)
 
   # Should be sufficient
   ggplot_build(p + scale_colour_manual(values = c("black", "black")))
@@ -122,7 +121,7 @@ test_that("fewer values (#3451)", {
   # unnamed character vector
   s2 <- scale_colour_manual(values = c("4", "8"), na.value = NA)
   s2$train(c("4", "6", "8"))
-  expect_error(s2$map(c("4", "6", "8")), "Insufficient values")
+  expect_snapshot(s2$map(c("4", "6", "8")), error = TRUE)
 })
 
 test_that("limits and breaks (#4619)", {
diff --git a/tests/testthat/test-scales-breaks-labels.R b/tests/testthat/test-scales-breaks-labels.R
index c3a314cacc..e15331c1f1 100644
--- a/tests/testthat/test-scales-breaks-labels.R
+++ b/tests/testthat/test-scales-breaks-labels.R
@@ -7,10 +7,8 @@ test_that("labels match breaks, even when outside limits", {
 })
 
 test_that("labels match breaks", {
-  expect_error(scale_x_discrete(breaks = 1:3, labels = 1:2),
-    "must have the same length")
-  expect_error(scale_x_continuous(breaks = 1:3, labels = 1:2),
-    "must have the same length")
+  expect_snapshot(scale_x_discrete(breaks = 1:3, labels = 1:2), error = TRUE)
+  expect_snapshot(scale_x_continuous(breaks = 1:3, labels = 1:2), error = TRUE)
 })
 
 test_that("labels don't have to match null breaks", {
@@ -152,20 +150,38 @@ test_that("suppressing breaks, minor_breask, and labels works", {
   lims <- as.Date(c("2000/1/1", "2000/2/1"))
   expect_null(scale_x_date(breaks = NULL, limits = lims)$get_breaks())
   # NA is defunct, should throw error
-  expect_error(scale_x_date(breaks = NA, limits = lims)$get_breaks())
+  expect_snapshot(
+    scale_x_date(breaks = NA, limits = lims)$get_breaks(),
+    error = TRUE
+  )
   expect_null(scale_x_date(labels = NULL, limits = lims)$get_labels())
-  expect_error(scale_x_date(labels = NA, limits = lims)$get_labels())
+  expect_snapshot(
+    scale_x_date(labels = NA, limits = lims)$get_labels(),
+    error = TRUE
+  )
   expect_null(scale_x_date(minor_breaks = NULL, limits = lims)$get_breaks_minor())
-  expect_error(scale_x_date(minor_breaks = NA, limits = lims)$get_breaks_minor())
+  expect_snapshot(
+    scale_x_date(minor_breaks = NA, limits = lims)$get_breaks_minor(),
+    error = TRUE
+  )
 
   # date, datetime
   lims <- as.POSIXct(c("2000/1/1 0:0:0", "2010/1/1 0:0:0"))
   expect_null(scale_x_datetime(breaks = NULL, limits = lims)$get_breaks())
-  expect_error(scale_x_datetime(breaks = NA, limits = lims)$get_breaks())
+  expect_snapshot(
+    scale_x_datetime(breaks = NA, limits = lims)$get_breaks(),
+    error = TRUE
+  )
   expect_null(scale_x_datetime(labels = NULL, limits = lims)$get_labels())
-  expect_error(scale_x_datetime(labels = NA, limits = lims)$get_labels())
+  expect_snapshot(
+    scale_x_datetime(labels = NA, limits = lims)$get_labels(),
+    error = TRUE
+  )
   expect_null(scale_x_datetime(minor_breaks = NULL, limits = lims)$get_breaks_minor())
-  expect_error(scale_x_datetime(minor_breaks = NA, limits = lims)$get_breaks_minor())
+  expect_snapshot(
+    scale_x_datetime(minor_breaks = NA, limits = lims)$get_breaks_minor(),
+    error = TRUE
+  )
 })
 
 test_that("scale_breaks with explicit NA options (deprecated)", {
@@ -174,34 +190,34 @@ test_that("scale_breaks with explicit NA options (deprecated)", {
   # X
   sxc <- scale_x_continuous(breaks = NA)
   sxc$train(1:3)
-  expect_error(sxc$get_breaks())
-  expect_error(sxc$get_breaks_minor())
+  expect_snapshot(sxc$get_breaks(), error = TRUE)
+  expect_snapshot(sxc$get_breaks_minor(), error = TRUE)
 
   # Y
   syc <- scale_y_continuous(breaks = NA)
   syc$train(1:3)
-  expect_error(syc$get_breaks())
-  expect_error(syc$get_breaks_minor())
+  expect_snapshot(syc$get_breaks(), error = TRUE)
+  expect_snapshot(syc$get_breaks_minor(), error = TRUE)
 
   # Alpha
   sac <- scale_alpha_continuous(breaks = NA)
   sac$train(1:3)
-  expect_error(sac$get_breaks())
+  expect_snapshot(sac$get_breaks(), error = TRUE)
 
   # Size
   ssc <- scale_size_continuous(breaks = NA)
   ssc$train(1:3)
-  expect_error(ssc$get_breaks())
+  expect_snapshot(ssc$get_breaks(), error = TRUE)
 
   # Fill
   sfc <- scale_fill_continuous(breaks = NA)
   sfc$train(1:3)
-  expect_error(sfc$get_breaks())
+  expect_snapshot(sfc$get_breaks(), error = TRUE)
 
   # Colour
   scc <- scale_colour_continuous(breaks = NA)
   scc$train(1:3)
-  expect_error(scc$get_breaks())
+  expect_snapshot(scc$get_breaks(), error = TRUE)
 })
 
 test_that("breaks can be specified by names of labels", {
diff --git a/tests/testthat/test-stat-bin.R b/tests/testthat/test-stat-bin.R
index 9b55054604..5baedf9223 100644
--- a/tests/testthat/test-stat-bin.R
+++ b/tests/testthat/test-stat-bin.R
@@ -194,7 +194,7 @@ test_that("setting boundary and center", {
   df <- data_frame(x = c(0, 30))
 
   # Error if both boundary and center are specified
-  expect_error(comp_bin(df, boundary = 5, center = 0), "one of `boundary` and `center`")
+  expect_snapshot(comp_bin(df, boundary = 5, center = 0), error = TRUE)
 
   res <- comp_bin(df, binwidth = 10, boundary = 0, pad = FALSE)
   expect_identical(res$count, c(1, 0, 1))
@@ -216,7 +216,7 @@ test_that("weights are added", {
 })
 
 test_that("bin errors at high bin counts", {
-  expect_error(bin_breaks_width(c(1, 2e6), 1), "The number of histogram bins")
+  expect_snapshot(bin_breaks_width(c(1, 2e6), 1), error = TRUE)
 })
 
 # stat_count --------------------------------------------------------------
diff --git a/tests/testthat/test-stat-ecdf.R b/tests/testthat/test-stat-ecdf.R
index ce839bb3c4..05fa8bc4b5 100644
--- a/tests/testthat/test-stat-ecdf.R
+++ b/tests/testthat/test-stat-ecdf.R
@@ -57,10 +57,7 @@ test_that("weighted ecdf warns about weird weights", {
   )
 
   # Should error when weights sum to 0
-  expect_error(
-    wecdf(1:10, rep(c(-1, 1), 5)),
-    "Cannot compute eCDF"
-  )
+  expect_snapshot(wecdf(1:10, rep(c(-1, 1), 5)), error = TRUE)
 })
 
 # See #5113 and #5112
diff --git a/tests/testthat/test-stats.R b/tests/testthat/test-stats.R
index 25c30e2fb1..af010a75b9 100644
--- a/tests/testthat/test-stats.R
+++ b/tests/testthat/test-stats.R
@@ -13,7 +13,7 @@ test_that("plot succeeds even if some computation fails", {
 
 test_that("error message is thrown when aesthetics are missing", {
   p <- ggplot(mtcars) + stat_sum()
-  expect_error(ggplot_build(p), "x and y\\.$")
+  expect_snapshot(ggplot_build(p), error = TRUE)
 })
 
 test_that("erroneously dropped aesthetics are found and issue a warning", {
diff --git a/tests/testthat/test-theme.R b/tests/testthat/test-theme.R
index 36ad577c65..cf98a1bb3f 100644
--- a/tests/testthat/test-theme.R
+++ b/tests/testthat/test-theme.R
@@ -49,7 +49,7 @@ test_that("modifying theme element properties with + operator works", {
   t <- theme_grey() + theme()
   expect_identical(t, theme_grey())
 
-  expect_error(theme_grey() + "asdf")
+  expect_snapshot(theme_grey() + "asdf", error = TRUE)
 })
 
 test_that("adding theme object to ggplot object with + operator works", {
@@ -115,7 +115,7 @@ test_that("replacing theme elements with %+replace% operator works", {
   t <- theme_grey() %+replace% theme()
   expect_identical(t, theme_grey())
 
-  expect_error(theme_grey() + "asdf")
+  expect_snapshot(theme_grey() + "asdf", error = TRUE)
 })
 
 test_that("calculating theme element inheritance works", {
@@ -368,10 +368,7 @@ test_that("elements can be merged", {
     merge_element(element_line(colour = "blue"), line_base),
     element_line(colour = "blue", linewidth = 10)
   )
-  expect_error(
-    merge_element(text_base, rect_base),
-    "Only elements of the same class can be merged"
-  )
+  expect_snapshot(merge_element(text_base, rect_base), error = TRUE)
 })
 
 test_that("theme elements that don't inherit from element can be combined", {