Add test file with a doppelganger-test

tests/testthat/test-position-nudgestack.R

@@ -0,0 +1,27 @@
+context("position_nudgestack")
+
+test_that("position_nudgestack draws correctly", {
+  ESM <- data_frame(
+    DAX = EuStockMarkets[colnames(EuStockMarkets) == "DAX"],
+    SMI = EuStockMarkets[colnames(EuStockMarkets) == "SMI"],
+    CAC = EuStockMarkets[colnames(EuStockMarkets) == "CAC"],
+    FTSE = EuStockMarkets[colnames(EuStockMarkets) == "FTSE"],
+    date = as.Date(paste(1, zoo::as.yearmon(time(EuStockMarkets))),
+      format = "%d %b %Y"
+    )
+  )
+
+  ESM_prep <- ESM %>%
+    tidyr::gather(key = key, value = value, -date) %>%
+    group_by(date, key) %>%
+    summarize(value = mean(value)) %>%
+    filter(date >= "1995-01-01" & date < "1998-01-01")
+
+  stock_marked <- ggplot(data = ESM_prep, mapping = aes(x = date, y = value, fill = key)) +
+    geom_col(position = position_nudgestack(x = 15))
+
+  expect_doppelganger(
+    "nudgestack EuStockMarkets data",
+    stock_marked
+  )
+})