Add test for package without registered functions

Fixes #29

Author: jimhester

tests/testthat/helper.R

@@ -19,3 +19,7 @@ glue_str <- function(...) {
 read_file <- function(x) {
   readChar(x, file.size(x))
 }
+
+expect_error_free <- function(..., regexp = NA) {
+  expect_error(..., regexp = regexp)
+}

tests/testthat/test-register.R

@@ -604,6 +604,15 @@ extern \"C\" void R_init_testPkg(DllInfo* dll){
       )
     )
   })
+
+  it("does not error if no files have registered functions", {
+    pkg <- local_package()
+    p <- pkg_path(pkg)
+    dir.create(file.path(p, "src"))
+    writeLines("int foo(int x) { return x; }", file.path(p, "src", "foo.cpp"))
+
+    expect_error_free(cpp_register(p))
+  })
 })
 
 describe("generate_init_functions", {