Add methods for boolean schemas

I wasn't sure whether to add methods to the existing class or to create
a new class. I'll see how this pans out.

lib/openapi3_parser/node/schema/v3_1.rb

@@ -15,6 +15,42 @@ class Schema < Node::Object
       # these complexities and focuses on the core schema as defined in:
       # https://json-schema.org/draft/2020-12/draft-bhutton-json-schema-validation-01
       class V3_1 < Schema # rubocop:disable Naming/ClassAndModuleCamelCase
+        # Whether this is a schema that is just a boolean value rather
+        # than a schema object
+        #
+        # @return [Boolean]
+        def boolean?
+          !boolean.nil?
+        end
+
+        # Returns a boolean for a boolean schema [1] and nil for one based
+        # on an object
+        #
+        # [1]: https://datatracker.ietf.org/doc/html/draft-bhutton-json-schema-00#section-4.3.2
+        #
+        # @return [Boolean, nil]
+        def boolean
+          self["boolean"]
+        end
+
+        # Returns true when this is a boolean schema that has a true value,
+        # returns false for booleans schemas that have a false value or schemas
+        # that are objects.
+        #
+        # @return [Boolean]
+        def true?
+          boolean == true
+        end
+
+        # Returns false when this is a boolean schema that has a false value,
+        # returns false for booleans schemas that have a true value or schemas
+        # that are objects.
+        #
+        # @return [Boolean]
+        def false?
+          boolean == false
+        end
+
         # @return [String, Node::Array<String>, nil]
         def type
           self["type"]

spec/lib/openapi3_parser/node/schema/v3_1_spec.rb

@@ -3,8 +3,51 @@
 RSpec.describe Openapi3Parser::Node::Schema::V3_1 do
   it_behaves_like "schema node", openapi_version: "3.1.0"
 
+  describe "boolean methods" do
+    let(:instance) do
+      factory_context = create_node_factory_context(input)
+
+      Openapi3Parser::NodeFactory::Schema::V3_1
+        .new(factory_context)
+        .node(node_factory_context_to_node_context(factory_context))
+    end
+
+    context "when given a boolean schema with a true value" do
+      let(:input) { true }
+
+      it "identifies as a boolean" do
+        expect(instance.boolean?).to be(true)
+        expect(instance.boolean).to be(true)
+        expect(instance.true?).to be(true)
+        expect(instance.false?).to be(false)
+      end
+    end
+
+    context "when given a boolean schema with a false value" do
+      let(:input) { false }
+
+      it "identifies as a boolean" do
+        expect(instance.boolean?).to be(true)
+        expect(instance.boolean).to be(false)
+        expect(instance.true?).to be(false)
+        expect(instance.false?).to be(true)
+      end
+    end
+
+    context "when given an object schema" do
+      let(:input) { { "type" => "string" } }
+
+      it "does not identify as a boolean" do
+        expect(instance.boolean?).to be(false)
+        expect(instance.boolean).to be_nil
+        expect(instance.true?).to be(false)
+        expect(instance.false?).to be(false)
+      end
+    end
+  end
+
   %i[if then else].each do |method_name|
-    describe method_name.to_s do
+    describe "##{method_name}" do
       it "supports a Ruby reserved word as a method name" do
         factory_context = create_node_factory_context(
           { method_name.to_s => { "type" => "string" } },