Refactor the test_examples function

Previously it would never run examples during R CMD check because there
was no '/man' directory for installed packages. This instead uses
tools::Rd_db to parse the Rd files into a database and uses that
directly, which does work for installed packages.

NAMESPACE

@@ -119,6 +119,7 @@ export(test_examples)
 export(test_file)
 export(test_package)
 export(test_path)
+export(test_rd)
 export(test_that)
 export(throws_error)
 export(try_again)

R/test-example.R

@@ -4,13 +4,26 @@
 #' Each example counts as one test, and it succeeds if the code runs without
 #' an error.
 #'
-#' @param path For \code{test_examples}, path to directory containing Rd files.
+#' @param path For \code{test_examples}, path to the package directory.
 #'   For \code{test_example}, path to a single Rd file. Remember the working
 #'   directory for tests is \code{tests/testthat}.
+#' @param rd A parsed Rd object, obtained from \code{\link[tools]{Rd_db}}.
 #' @export
-test_examples <- function(path = "../../man") {
-  man <- dir(path, "\\.Rd$", full.names = TRUE)
-  lapply(man, test_example)
+test_examples <- function(path = "../..") {
+  Rd <- NULL
+  if (dir.exists(file.path(path, "man"))) {
+    Rd <- tools::Rd_db(dir = path)
+  } else {
+    # Installed packages (like when run from R CMD check) do not have a /man
+    # directory, so we need to find the Rd files using the package name.
+    if (!is.null(env_test$package)) {
+      Rd <- tools::Rd_db(env_test$package)
+    }
+  }
+  if (is.null(Rd)) {
+    stop("Could not find examples", call. = FALSE)
+  }
+  lapply(Rd, test_rd)
 }
 
 #' @export
@@ -22,9 +35,24 @@ test_example <- function(path) {
 
   env <- new.env(parent = globalenv())
 
-  ok <- test_code(path, parse(ex_path), env = globalenv())
+  ok <- test_code(path, parse(ex_path), env = env)
   if (ok) succeed(path)
 
   invisible()
 }
 
+#' @export
+#' @rdname test_examples
+test_rd <- function(rd) {
+  path <- attr(rd, "Rdfile")
+  ex_path <- file.path(tempdir(), paste0(tools::file_path_sans_ext(basename(path)), ".R"))
+  tools::Rd2ex(rd, ex_path)
+  if (!file.exists(ex_path)) return()
+
+  env <- new.env(parent = globalenv())
+
+  ok <- test_code(path, parse(ex_path), env = env)
+  if (ok) succeed(path)
+
+  invisible()
+}