Handle cases when the examples contain runtime or install time Sexpr blocks

In these cases the package being tested can be implicitly loaded, so we
need to make sure the libpaths are set appropriately so the transformed
version of the package is used.

Fixes #488

Author: jimhester

NEWS.md

@@ -4,6 +4,7 @@
   the trace of the tests being executed and adds an itemization of which tests
   result in the execution of each trace. For more details see
   `?covr.record_tests` (@dgkf, #463, #485)
+* `package_coverage()` now handles packages with install or render time examples (#488)
 
 * `package_coverage()` now sets the environment variable `R_TESTS` to the tests-startup.R file like R CMD check does (#420)
 

R/covr.R

@@ -425,6 +425,11 @@ package_coverage <- function(path = ".",
 
   libs <- env_path(install_path, .libPaths())
 
+  # We need to set the libpaths in the current R session for examples with
+  # install or runtime Sexpr blocks, which may implicitly load the package in
+  # the current R session.
+  withr::with_libpaths(install_path, action = "prefix", {
+
   withr::with_envvar(
     c(R_DEFAULT_PACKAGES = "datasets,utils,grDevices,graphics,stats,methods",
       R_LIBS = libs,
@@ -466,6 +471,7 @@ package_coverage <- function(path = ".",
     message = function(e) if (quiet) invokeRestart("muffleMessage") else e,
     warning = function(e) if (quiet) invokeRestart("muffleWarning") else e)
     })
+    })
 
   # read tracing files
   trace_files <- list.files(path = install_path, pattern = "^covr_trace_[^/]+$", full.names = TRUE)