added helper-state test

tests/testthat/helper-state.R

@@ -0,0 +1,26 @@
+# This helper ensures the package does not modify the session global state. As
+# per CRAN policy, packages should not interfere with the user's session state.
+# If global settings need to be modified, they should be restored to their
+# original values on exit. This can be achieved with the `on.exit()` base
+# function, or more conveniently with the `withr` package.
+# We add a test on R >= 4.0.0 because some functions such as
+# `globalCallingHandlers()` did not exist before.
+if (getRversion() >= "4.0.0") {
+  testthat::set_state_inspector(function() {
+    list(
+      attached    = search(),
+      connections = getAllConnections(),
+      cwd         = getwd(),
+      envvars     = Sys.getenv(),
+      handlers    = globalCallingHandlers(),
+      libpaths    = .libPaths(),
+      locale      = Sys.getlocale(),
+      options     = options(),
+      par         = par(),
+      packages    = .packages(all.available = TRUE),
+      sink        = sink.number(),
+      timezone    = Sys.timezone(),
+      NULL
+    )
+  })
+}