Unexpected behavior with internal trailing slashes if not following redirects

In upgrading from 3.x to 5.x, we've noticed a change in behavior with how `followlocation` affects internal link checking with trailing slashes. Specifically, we want to enforce that internal links have trailing slashes, but `html-proofer` produces errors even if they do have trailing slashes. It seems to be enforcing the _absence_ of a trailing slash, despite the error message indicating that it lacks one. I was able to imitate what we're expecting with a failing spec as a proof of concept: ```diff diff --git a/spec/html-proofer/check/links_spec.rb b/spec/html-proofer/check/links_spec.rb index f50154b..4a054c6 100644 --- a/spec/html-proofer/check/links_spec.rb +++ b/spec/html-proofer/check/links_spec.rb @@ -326,2 +326,9 @@ describe "Check::Links" do + it "allows for internal linking to a directory with trailing slash when not following" do + options = { typhoeus: { followlocation: false } } + internal = File.join(FIXTURES_DIR, "links", "link_to_folder.html") + proofer = run_proofer(internal, :file, options) + expect(proofer.failed_checks).to(eq([])) + end + it "fails for internal linking to a directory without trailing slash" do ``` Example error in our project: ``` * At /Code/_site/index.html:203: internally linking to a directory / without trailing slash ``` Corresponding markup in `index.html`: ```html <a href="/" lang="en" hreflang="en"> English </a> ``` The behavior seems to stem from `File.expand_path` in `HTMLProofer::Attribute::Url#absolute_path`, which strips the trailing slash: https://github.com/gjtorikian/html-proofer/blob/590336026ee84e7a416a5e1ea80ff2e925fc91db/lib/html_proofer/attribute/url.rb#L151-L155 ```rb File.expand_path('/Code/_site/', '/Code/_site/') # "/Code/_site" ``` Since `absolute_path` is used as the `unslashed_directory?` argument, the unslashing produces a failure. https://github.com/gjtorikian/html-proofer/blob/590336026ee84e7a416a5e1ea80ff2e925fc91db/lib/html_proofer/check/links.rb#L59