Serialize aria- namespaced list attributes

Summary
===

Prior to this commit, calls passing `aria: { labelledby: [...] }`
serialized the `aria-labelledby` Array value as JSON.

This commit introduces special case logic to serialize `aria-` prefixed
`TrueClass`, `FalseClass`, `Hash`, and `Array` values more
appropriately.

An element's [`aria-labelledby` attribute][aria-labelledby] and
[`aria-describedby` attribute][aria-describedby] can accept a
space-delimited list of identifier values (much like the [`class`
attribute][class] accepts a space delimited [`DOMTokenList`
value][DOMTokenList]).

Similarly, there are [no boolean `aria-` attributes][aria-attributes]
(only `true`, `false`, or undefined), so this commit serializes `true`
to `"true"` and `false` to `"false"`.

Testing
---

This change moves an assertion _outside_ of a loop over `["aria",
:aria]`. Prior to this change, the second assertion within the loop
wasn't utilizing the iterated value as a Hash key. That is to say:
`aria:` (where an `aria` local variable is declared) is not equivalent
an equivalent syntax to `aria =>`.

Since the migration to `**options` in response to Ruby 2.7 deprecations,
invoking `tag.a("aria" => {...})` incorrectly coerces the `"aria" =>
{...}` has to be the `TagBuilder#a` method `content = nil` ordered
argument, instead of its `options` keyword arguments. This commit does
not modify that behavior, but it _does_ move the assertion outside the
block so that it isn't run unnecessarily.

[aria-labelledby]: https://developer.mozilla.org/en-US/docs/Web/Accessibility/ARIA/ARIA_Techniques/Using_the_aria-labelledby_attribute
[aria-describedby]: https://developer.mozilla.org/en-US/docs/Web/Accessibility/ARIA/ARIA_Techniques/Using_the_aria-describedby_attribute
[aria-attributes]: https://www.w3.org/TR/wai-aria-1.1/#propcharacteristic_value
[class]: https://developer.mozilla.org/en-US/docs/Web/HTML/Global_attributes/class
[DOMTokenList]: https://developer.mozilla.org/en-US/docs/Web/API/DOMTokenList
[class_names]: https://edgeapi.rubyonrails.org/classes/ActionView/Helpers/TagHelper.html#method-i-class_names

actionview/CHANGELOG.md

@@ -1,3 +1,20 @@
+*   ARIA Array and Hash attributes are treated as space separated `DOMTokenList`
+    values. This is useful when declaring lists of label text identifiers in
+    `aria-labelledby` or `aria-describedby`.
+
+        tag.input type: 'checkbox', name: 'published', aria: {
+          invalid: @post.errors[:published].any?,
+          labelledby: ['published_context', 'published_label'],
+          describedby: { published_errors: @post.errors[:published].any? }
+        }
+        #=> <input
+              type="checkbox" name="published" aria-invalid="true"
+              aria-labelledby="published_context published_label"
+              aria-describedby="published_errors"
+            >
+
+    *Sean Doyle*
+
 *   Remove deprecated `escape_whitelist` from `ActionView::Template::Handlers::ERB`.
 
     *Rafael Mendonça França*

actionview/lib/action_view/helpers/tag_helper.rb

@@ -26,11 +26,13 @@ module ActionView
       BOOLEAN_ATTRIBUTES.merge(BOOLEAN_ATTRIBUTES.map(&:to_sym))
       BOOLEAN_ATTRIBUTES.freeze
 
-      TAG_PREFIXES = ["aria", "data", :aria, :data].to_set.freeze
+      ARIA_PREFIXES = ["aria", :aria].to_set.freeze
+      DATA_PREFIXES = ["data", :data].to_set.freeze
 
       TAG_TYPES = {}
       TAG_TYPES.merge! BOOLEAN_ATTRIBUTES.index_with(:boolean)
-      TAG_TYPES.merge! TAG_PREFIXES.index_with(:prefix)
+      TAG_TYPES.merge! DATA_PREFIXES.index_with(:data)
+      TAG_TYPES.merge! ARIA_PREFIXES.index_with(:aria)
       TAG_TYPES.freeze
 
       PRE_CONTENT_STRINGS             = Hash.new { "" }
@@ -72,9 +74,18 @@ module ActionView
           sep    = " "
           options.each_pair do |key, value|
             type = TAG_TYPES[key]
-            if type == :prefix && value.is_a?(Hash)
+            if type == :data && value.is_a?(Hash)
               value.each_pair do |k, v|
                 next if v.nil?
+                output << sep
+                output << prefix_tag_option(key, k, v, escape)
+              end
+            elsif type == :aria && value.is_a?(Hash)
+              value.each_pair do |k, v|
+                next if v.nil?
+
+                v = (v.is_a?(Array) || v.is_a?(Hash)) ? safe_join(TagHelper.build_tag_values(v), " ") : v.to_s
+
                 output << sep
                 output << prefix_tag_option(key, k, v, escape)
               end
@@ -165,8 +176,8 @@ module ActionView
       #   tag.input type: 'text', disabled: true
       #   # => <input type="text" disabled="disabled">
       #
-      # HTML5 <tt>data-*</tt> attributes can be set with a single +data+ key
+      # HTML5 <tt>data-*</tt> and <tt>aria-*</tt> attributes can be set with a
-      # pointing to a hash of sub-attributes.
+      # single +data+ or +aria+ key pointing to a hash of sub-attributes.
       #
       # To play nicely with JavaScript conventions, sub-attributes are dasherized.
       #

actionview/test/template/tag_helper_test.rb

@@ -441,11 +441,12 @@ class TagHelperTest < ActionView::TestCase
 
   def test_aria_attributes
     ["aria", :aria].each { |aria|
-      assert_dom_equal '<a aria-a-float="3.14" aria-a-big-decimal="-123.456" aria-a-number="1" aria-array="[1,2,3]" aria-hash="{&quot;key&quot;:&quot;value&quot;}" aria-string-with-quotes="double&quot;quote&quot;party&quot;" aria-string="hello" aria-symbol="foo" />',
+      assert_dom_equal '<a aria-a-float="3.14" aria-a-big-decimal="-123.456" aria-a-number="1" aria-truthy="true" aria-falsey="false" aria-array="1 2 3" aria-hash="a b" aria-tokens="a b" aria-string-with-quotes="double&quot;quote&quot;party&quot;" aria-string="hello" aria-symbol="foo" />',
-        tag("a", aria => { a_float: 3.14, a_big_decimal: BigDecimal("-123.456"), a_number: 1, string: "hello", symbol: :foo, array: [1, 2, 3], hash: { key: "value" }, string_with_quotes: 'double"quote"party"' })
+        tag("a", aria => { nil: nil, a_float: 3.14, a_big_decimal: BigDecimal("-123.456"), a_number: 1, truthy: true, falsey: false, string: "hello", symbol: :foo, array: [1, 2, 3], hash: { a: true, b: "truthy", falsey: false, nil: nil }, tokens: ["a", { b: true, c: false }], string_with_quotes: 'double"quote"party"' })
-      assert_dom_equal '<a aria-a-float="3.14" aria-a-big-decimal="-123.456" aria-a-number="1" aria-array="[1,2,3]" aria-hash="{&quot;key&quot;:&quot;value&quot;}" aria-string-with-quotes="double&quot;quote&quot;party&quot;" aria-string="hello" aria-symbol="foo" />',
-        tag.a(aria: { a_float: 3.14, a_big_decimal: BigDecimal("-123.456"), a_number: 1, string: "hello", symbol: :foo, array: [1, 2, 3], hash: { key: "value" }, string_with_quotes: 'double"quote"party"' })
     }
+
+    assert_dom_equal '<a aria-a-float="3.14" aria-a-big-decimal="-123.456" aria-a-number="1" aria-truthy="true" aria-falsey="false" aria-array="1 2 3" aria-hash="a b" aria-tokens="a b" aria-string-with-quotes="double&quot;quote&quot;party&quot;" aria-string="hello" aria-symbol="foo" />',
+    tag.a(aria: { nil: nil, a_float: 3.14, a_big_decimal: BigDecimal("-123.456"), a_number: 1, truthy: true, falsey: false, string: "hello", symbol: :foo, array: [1, 2, 3], hash: { a: true, b: "truthy", falsey: false, nil: nil }, tokens: ["a", { b: true, c: false }], string_with_quotes: 'double"quote"party"' })
   end
 
   def test_link_to_data_nil_equal