fix: upgrade mml to 2.3.2 to make things work

.rubocop_todo.yml

@@ -1,24 +1,25 @@
 # This configuration was generated by
 # `rubocop --auto-gen-config`
-# on 2026-04-04 03:19:03 UTC using RuboCop version 1.86.0.
+# on 2026-04-15 09:29:09 UTC using RuboCop version 1.86.1.
 # The point is for the user to remove these configuration records
 # one by one as the offenses are removed from the code base.
 # Note that changes in the inspected code, or installation of new
 # versions of RuboCop, may require this file to be generated again.
 
-# Offense count: 2
-# This cop supports safe autocorrection (--autocorrect).
-# Configuration parameters: TreatCommentsAsGroupSeparators, ConsiderPunctuation.
-Bundler/OrderedGems:
-  Exclude:
-    - 'Gemfile'
-
 # Offense count: 1
 Gemspec/RequiredRubyVersion:
   Exclude:
     - 'unitsml.gemspec'
 
-# Offense count: 75
+# Offense count: 1
+# This cop supports safe autocorrection (--autocorrect).
+# Configuration parameters: EnforcedStyle, IndentationWidth.
+# SupportedStyles: with_first_argument, with_fixed_indentation
+Layout/ArgumentAlignment:
+  Exclude:
+    - 'lib/unitsml/unit.rb'
+
+# Offense count: 76
 # This cop supports safe autocorrection (--autocorrect).
 # Configuration parameters: Max, AllowHeredoc, AllowURI, AllowQualifiedName, URISchemes, AllowRBSInlineAnnotation, AllowCopDirectives, AllowedPatterns, SplitStrings.
 # URISchemes: http, https
@@ -40,6 +41,13 @@ Layout/LineLength:
     - 'spec/unitsml/conv/xml_spec.rb'
     - 'unitsml.gemspec'
 
+# Offense count: 1
+# This cop supports safe autocorrection (--autocorrect).
+# Configuration parameters: AllowInHeredoc.
+Layout/TrailingWhitespace:
+  Exclude:
+    - 'lib/unitsml/unit.rb'
+
 # Offense count: 3
 Lint/ReturnInVoidContext:
   Exclude:
@@ -160,6 +168,12 @@ RSpec/SpecFilePathFormat:
     - 'spec/unitsml/conv/unicode_spec.rb'
     - 'spec/unitsml/conv/xml_spec.rb'
 
+# Offense count: 1
+# This cop supports safe autocorrection (--autocorrect).
+Style/MultilineIfModifier:
+  Exclude:
+    - 'lib/unitsml/unit.rb'
+
 # Offense count: 2
 # Configuration parameters: AllowedMethods.
 # AllowedMethods: respond_to_missing?

Gemfile

@@ -7,7 +7,6 @@ gemspec
 
 gem "canon"
 gem "lutaml-model", "~> 0.8.0", github: "lutaml/lutaml-model", branch: "main"
-gem "mml"
 gem "oga"
 gem "ox"
 gem "plurimath", github: "plurimath/plurimath", branch: "rt-lutaml-080"

lib/unitsml/formula.rb

@@ -196,10 +196,14 @@ def plurimath_available?
     end
 
     def nullify_mml_models
+      return unless defined?(Plurimath::Mathml::Parser::CONFIGURATION)
+
       Plurimath::Mathml::Parser::CONFIGURATION.each_key { |klass| klass.model(klass) }
     end
 
     def reset_mml_models
+      return unless defined?(Plurimath::Mathml::Parser::CONFIGURATION)
+
       ::Mml::V4::Configuration.custom_models = Plurimath::Mathml::Parser::CONFIGURATION
     end
 

lib/unitsml/unit.rb

@@ -35,10 +35,14 @@ def unit_symbols
     end
 
     def to_mathml(options)
-      value = unit_symbols&.mathml
-      tag_name = value.match(/^<(?<tag>\w+)/)[:tag]
-      value = ::Mml::V4.const_get(tag_name.capitalize).from_xml(value)
-      value.value = "#{prefix.to_mathml(options)}#{value.value}" if prefix
+      raw_mathml = unit_symbols&.mathml
+      tag_name = raw_mathml.match(/^<(?<tag>\w+)/)[:tag]
+      klass = ::Mml::V4.const_get(tag_name.capitalize)
+      value = klass.from_xml(raw_mathml)
+      if prefix
+        value = with_updated_value(value,
+                                   "#{prefix.to_mathml(options)}#{value.value}")
+      end
       if power_numerator
         value = msup_tag(
           { method_name: tag_name, value: value },
@@ -126,6 +130,15 @@ def system_reference
       unit_instance.unit_system_reference
     end
 
+    def with_updated_value(element, new_value)
+      attrs = element.class.attributes.each_with_object({}) do |(name, _), h|
+        val = element.public_send(name)
+        h[name] = val unless val.nil?
+      end
+      attrs[:value] = new_value
+      element.class.new(**attrs)
+    end
+
     def msup_tag(value, options)
       msup = ::Mml::V4::Msup.new
       msup.ordered = true