I confirmed that it fails on:
rustdoc 1.30.0-beta.12 (96a22982 2018-10-04)
and passes on:
rustdoc 1.31.0-nightly (f99911a4 2018-10-23)

The dyn keyword has been stable for a while now so rustdoc should start using it.

There was an issue (#33025) which caused these tests to not work. The issue has
since been fixed in #33133, and so we can now include them.

The function is called `fn_def_with_doc`, not `fn_def_with`.

The link that is matched against is not the same as would be generated by
rustdoc. We should also check that the `foo/private` directory is not generated
at all.

The generated code would look like `<code>impl <a href="...">Foo</a></code>`
which the plain text matcher doesn't match. But by using the XPATH notation, the
nodes are flattened and we can correctly assert that `impl Foo` does not occur
in the generated docs.

The Auto Trait Implementation section is not wrapped in a
`synthetic-implementations` class. In fact, it is wrapped in a
`synthetic-implementations` id. However, we can generalize and completely remove
the `synthetic-implementations` requirement. We just have to verify that there's
no mention of "Auto Trait Implementations" anywhere.

Struct names are no longer encapsulated in `<code>` tags, which meant that the
test was not correctly verifying that it wasn't being show. I've also added a
check to make sure the documentation page for the redirect::Qux struct is not
generated at all.

The `@!has` command does not support specifying just a PATH and an XPATH. That
means that the previous test searched for the literal string
`//h2[@id="implementations"]` within the generated output, which obviously
didn't exist. Even after adding a trait implementation, the test still passed.
The correct way to check for the existence of a DOM element with the id
`implementations` is to use the `@count` keyword.

"Run" links to the playground are not added to the generated documentation if
the unstable `--playground-url` argument is not passed to rustdoc. Therefore,
without specifying `--playground-url` as a compile-flag, the test doesn't
correctly assert that `#![doc(html_playground_url = "")]` removes playground
links.

The old test was supposed to check for proper html escaping when showing the
contents of constants. This was changed as part of #53409. The revised test
asserts that the contents of the constant is not shown as part of the generated
documentation.

those get handled properly in strip-hidden anyway

The way it defines implementations is unrealistic though.

`bad_style` is being deprecated in favor of `nonstandard_style`:

- https://github.com/rust-lang/rust/issues/41646