add helper function to mask testthat::test_path until bug fix is merg…

…ed into testhat

tests/testthat/helper.R

@@ -0,0 +1,10 @@
+test_path <- function(...) {
+  # testthat::test_path() returns incorrect value
+  # when in the context of devtools::test_coverage_active_file()
+  path <- file.path(...)
+  if (file.exists(path)) {
+    path
+  } else {
+    file.path("tests/testthat/", path)
+  }
+}