Add support for Ruby 3.1 (#2635)

* Add ci for Ruby 3.1

* Don't start SimpleCov more than once

In Ruby >= 3.1 it is an error to call `SimpleCov.start` more than once
(see simplecov-ruby/simplecov#1003).

This commit changes the shared configuration files to call
`SimpleCov.configure` instead of `SimpleCov.start`, to work around this
issue.

* Fix issue with dates in YAML config with Ruby >= 3.1

This commit fixes a issue #2614.

In middleman <= 4.4.3, if your YAML config file has something that looks
like an date (in ISO format), then you get the error

  YAML Exception ...: Tried to load unspecified class: Date

Including a properly formatted date in the frontmatter is a fairly
common use-case.

This happens Ruby 3.1 upgraded the included YAML library [Psych] to the
4.x branch, which changes `YAML.load` to call `Psych.safe_load` instead
of `Psych.unsafe_load`. This means it no longer parses dates unless it's
provided with `permitted_classes: [Date, ...]`.

The currently released versions of middleman (4.4.3 and 5.0.0-rc1) call
`YAML.load`, so the behavour depends on your ruby version.

This commit fixes things by using `YAML.safe_load` instead of
`YAML.load`, and allowing dates. Note that we have to do some
introspection of the arguments to YAML.safe_load to name the keyword
argument correctly, because in older versions of Ruby this argument had
a different name or wasn't a keyword argument [[1]], and we want to
retain support for those old versions.

[Psych]: https://github.com/ruby/psych

[1]: ruby/psych@682abf2

.github/workflows/ci.yml

@@ -8,7 +8,7 @@ jobs:
     name: ubuntu-ruby-${{ matrix.ruby-version }}
     strategy:
       matrix:
-        ruby-version: ["3.0", "2.7", "2.6", "2.5"]
+        ruby-version: ["3.1", "3.0", "2.7", "2.6", "2.5"]
     steps:
       - uses: actions/checkout@v2
       - name: Set up Ruby

middleman-cli/.simplecov

@@ -1,7 +1,7 @@
-SimpleCov.start do
+SimpleCov.configure do
   add_filter '/fixtures/'
   add_filter '/features/'
   add_filter '/spec/'
   add_filter '/step_definitions/'
   add_filter '/lib/vendored-middleman-deps/'
-end
+end

middleman-core/.simplecov

@@ -1,7 +1,7 @@
-SimpleCov.start do
+SimpleCov.configure do
   add_filter '/fixtures/'
   add_filter '/features/'
   add_filter '/spec/'
   add_filter '/step_definitions/'
   add_filter '/lib/vendored-middleman-deps/'
-end
+end

middleman-core/lib/middleman-core/util/data.rb

@@ -118,9 +118,17 @@ def build_regex(frontmatter_delims)
       # @return [Hash]
       Contract String, Pathname => Hash
       def parse_yaml(content, full_path)
+        permitted_classes = [Date, Symbol]
         c = begin
           ::Middleman::Util.instrument 'parse.yaml' do
-            ::YAML.load(content)
+            allowed_parameters = ::YAML.method(:safe_load).parameters
+            if allowed_parameters.include? [:key, :permitted_classes]
+              ::YAML.safe_load(content, permitted_classes: permitted_classes)
+            elsif allowed_parameters.include? [:key, :whitelist_classes]
+              ::YAML.safe_load(content, whitelist_classes: permitted_classes)
+            else
+              ::YAML.safe_load(content, permitted_classes)
+            end
           end
         rescue StandardError, ::Psych::SyntaxError => error
           warn "YAML Exception parsing #{full_path}: #{error.message}"

middleman/.simplecov

@@ -1,5 +1,5 @@
-SimpleCov.start do
+SimpleCov.configure do
   add_filter '/fixtures/'
   add_filter '/features/'
   add_filter '/spec/'
-end
+end