test: Add regression tests

- Add function that run examples and store results in RDS files for CRAN and dev versions of airGR package
- Add test for comparing the 2 versions of results files

Refs #59

tests/testthat/store_examples.R

+StoreRefExampleResults <- function(package, ...) {
+  install.packages(package)
+  StoreExampleResults(package = package, path = "tests/tmp/ref", ...)
+}
+
+StoreTestExampleResults <- function(package, ...) {
+  StoreExampleResults(package = package, path = "tests/tmp/test", ...)
+}
+
+#' Run examples of a package and store the output variables in RDS files for further testing.
+#'
+#' @param package Name of the package from which examples are tested.
+#' @param path Path where to record the files.
+#' @param run.dontrun See \code{\link{example}}.
+#' @param run.donttest See \code{\link{example}}.
+#'
+#' @return
+#' @export
+#'
+#' @examples
+StoreExampleResults <- function(package, path, run.dontrun = FALSE, run.donttest = TRUE) {
+
+  # Install and load stable version of the package
+  library(package, character.only = TRUE)
+  
+  # Get the list of documentation pages
+  rd <- unique(readRDS(system.file("help", "aliases.rds", package = package)))
+  
+  dir.create(path, showWarnings = FALSE)
+  
+  lapply(
+    rd, 
+    StoreTopicResults, 
+    package, path, run.dontrun = run.dontrun, run.donttest = run.donttest
+  )
+}
+
+StoreTopicResults <- function(topic, package, path, run.dontrun = TRUE, run.donttest = TRUE) {
+  
+  cat("*******************************\n")
+  cat("*", topic, "\n")
+  cat("*******************************\n")
+
+  par(ask=F) #https://stackoverflow.com/questions/34756905/how-to-turn-off-the-hit-return-to-see-next-plot-prompt-plot3d
+
+  varBefore <- c()
+  varBefore <- ls(envir = globalenv())
+
+  example(
+    topic, package = package, character.only = TRUE, echo = FALSE, ask = FALSE, local = FALSE, setRNG = TRUE,
+    run.dontrun = run.dontrun, run.donttest = run.donttest
+  )
+  dev.off()
+  
+  varAfter <- ls(envir = globalenv())
+  
+  varToSave <- setdiff(varAfter, varBefore)
+  
+  if(length(varToSave) > 0) {
+    path <- file.path(path, topic)
+    dir.create(path, showWarnings = FALSE, recursive = TRUE)
+    lapply(varToSave, function(x) {
+      saveRDS(get(x), file = file.path(path, paste0(x, ".rds")))
+    })
+  }
+  
+  rm(list = varToSave, envir = globalenv())
+  
+}
+

tests/testthat/test-regression.R

+context("Compare example outputs with CRAN")
+
+CompareWithRef <- function(refVarFile, testDir, regIgnore) {
+  v <- data.frame(
+    topic = basename(dirname(refVarFile)),
+    var = gsub("\\.rds$", "", basename(refVarFile))
+  )
+  if(is.null(regIgnore) || all(apply(regIgnore, 1, function(x) {!all(x == v)}))) {
+    test_that(paste("Compare", v$topic, v$var), {
+      skip_on_cran()
+      testVarFile <- paste0("../tmp/test/", file.path(v$topic, v$var), ".rds")
+      expect_true(file.exists(testVarFile))
+      if(file.exists(testVarFile)) {
+        testVar <- readRDS(testVarFile)
+        refVar <- readRDS(refVarFile)
+        expect_equivalent(testVar, refVar)
+      }
+    })
+  }
+}
+
+if(dir.exists("../tmp/ref") & dir.exists("../tmp/test")) {
+  refVarFiles <- list.files("../tmp/ref", recursive = TRUE, full.names = TRUE)
+  regIgnoreFile <- "../../.regressionignore2"
+  if(file.exists(regIgnoreFile)) {
+    regIgnore <- read.table(
+      file = regIgnoreFile, 
+      sep = " ", header = FALSE, skip = 5, col.names = c("topic", "var"), 
+      stringsAsFactors = FALSE
+    )
+  } else {
+    regIgnore <- NULL
+  }
+  lapply(X = refVarFiles, CompareWithRef, testDir = "../tmp/test", regIgnore = regIgnore)
+} else {
+  warning("Regression tests compared to released version needs that you run the following instructions first:\n",
+          "Rscript -e 'source(\"tests/testthat/store_examples.R\"); StoreRefExampleResults(\"airGR\");'\n",
+          "R CMD INSTALL .\n",
+          "Rscript -e 'source(\"tests/testthat/store_examples.R\"); StoreTestExampleResults(\"airGR\");'\n")
+}
+
+