Add FullNameFormatter

This adds a class which formats a full name (made up of a given name and
a family name) in given format context, either internal use or
communication with parents.

The internal use format will use "FAMILY, Given" as the format and for
parents it will remain as "Given Family".

app/lib/full_name_formatter.rb

@@ -0,0 +1,23 @@
+# frozen_string_literal: true
+
+class FullNameFormatter
+  def self.call(nameable, context:, parts_prefix: nil)
+    parts_prefix = "#{parts_prefix}_" if parts_prefix.present?
+
+    given_name =
+      nameable.try(:"#{parts_prefix}given_name").presence ||
+        nameable.send(:given_name)
+    family_name =
+      nameable.try(:"#{parts_prefix}family_name").presence ||
+        nameable.send(:family_name)
+
+    case context
+    when :internal
+      "#{family_name.upcase}, #{given_name.upcase_first}"
+    when :parents
+      "#{given_name.upcase_first} #{family_name.upcase_first}"
+    else
+      raise "Unknown context: #{context}"
+    end
+  end
+end

spec/lib/full_name_formatter_spec.rb

@@ -0,0 +1,53 @@
+# frozen_string_literal: true
+
+describe FullNameFormatter do
+  context "with no parts prefix" do
+    subject { described_class.call(nameable, context:) }
+
+    let(:nameable) { OpenStruct.new(given_name: "John", family_name: "Smith") }
+
+    context "with internal context" do
+      let(:context) { :internal }
+
+      it { should eq("SMITH, John") }
+    end
+
+    context "with parents context" do
+      let(:context) { :parents }
+
+      it { should eq("John Smith") }
+    end
+  end
+
+  context "with a parts prefix" do
+    subject do
+      described_class.call(nameable, context: :parents, parts_prefix: :parent)
+    end
+
+    let(:nameable) do
+      OpenStruct.new(parent_given_name: "John", parent_family_name: "Smith")
+    end
+
+    it { should eq("John Smith") }
+  end
+
+  context "with a multi-case name" do
+    subject { described_class.call(nameable, context:) }
+
+    let(:nameable) do
+      OpenStruct.new(given_name: "John", family_name: "MacGyver")
+    end
+
+    context "with internal context" do
+      let(:context) { :internal }
+
+      it { should eq("MACGYVER, John") }
+    end
+
+    context "with parents context" do
+      let(:context) { :parents }
+
+      it { should eq("John MacGyver") }
+    end
+  end
+end