Use local_package_copy() for test writing to test path (#1685)

Author: MichaelChirico

tests/testthat/test-namespace.R

@@ -381,7 +381,7 @@ test_that("rawNamespace inserted unchanged", {
 })
 
 test_that("rawNamespace does not break idempotency", {
-  test_pkg <- test_path("testRawNamespace")
+  test_pkg <- local_package_copy(test_path("testRawNamespace"))
   NAMESPACE <- file.path(test_pkg, "NAMESPACE")
 
   lines_orig <- read_lines(NAMESPACE)