message: Verify that private items were actually documented
diff: @@ -1557,10 +1557,10 @@ fn doc_private_items() {
  version = "0.0.1"
  "#,
  )
  - .file("src/lib.rs", "fn private_item() {}")
  + .file("src/lib.rs", "mod private { fn private_item() {} }")
  .build();
  assert_that(foo.cargo("doc").arg("--document-private-items"), execs().with_status(0));
  assert_that(&foo.root().join("target/doc"), existing_dir());
  - assert_that(&foo.root().join("target/doc/foo/index.html"), existing_file());
  + assert_that(&foo.root().join("target/doc/foo/private/index.html"), existing_file());
  }
  