When creating a Rash, one can specify the preferred format of certain…

… keys

lib/stacker_bee/rash.rb

@@ -12,8 +12,11 @@ class Rash
       :flatten, :invert, :keys, :key, :merge, :rassoc, :to_a, :to_h, :to_hash
     ]
 
-    def initialize(hash = {})
+    def initialize(hash = {}, preferred_keys = [])
       @hash = {}
+
+      save_preferred_keys preferred_keys
+
       hash.each_pair do |key, value|
         @hash[convert_key(key)] = convert_value(value)
       end
@@ -78,7 +81,27 @@ def self.deep_dup(hash)
     end
 
     def convert_key(key)
-      key.is_a?(Numeric) ? key : uncase(key)
+      if key.is_a?(Numeric)
+        key
+      elsif preferred_key_format?(key)
+        preferred_key_format(key)
+      else
+        uncase(key)
+      end
+    end
+
+    def save_preferred_keys(keys)
+      @preferred_keys = keys.each_with_object({}) do |key, mapping|
+        mapping[uncase(key)] = key
+      end
+    end
+
+    def preferred_key_format?(key)
+      @preferred_keys.key?(uncase(key))
+    end
+
+    def preferred_key_format(key)
+      @preferred_keys[uncase(key)]
     end
 
     def convert_value(value)

spec/units/stacker_bee/rash_spec.rb

@@ -3,7 +3,7 @@
 end
 
 describe StackerBee::Rash do
-  subject { rash }
+  subject(:rash) { described_class.new(hash) }
 
   let(:wiz) { [{ 'aB_C' => 'abc' }, { 'X_yZ' => 'xyz' }] }
   let(:ziz) do
@@ -28,7 +28,6 @@
     end
   end
   let(:dissimilar_hash) { hash.dup.tap { |loud| loud.delete 'foo' } }
-  let(:rash) { described_class.new(hash) }
 
   it { is_expected.to include 'FOO' }
 
@@ -82,4 +81,21 @@
     subject { rash.values_at 'FOO', 'WIZ', 'WRONG' }
     it { is_expected.to eq ['foo', wiz, nil] }
   end
+
+  describe 'with preferred keys' do
+    subject { described_class.new(hash, preferred_keys) }
+    let(:preferred_keys) { [:foo, 'BAR', :b_a_z] }
+    let(:hash) do
+      {
+        f_o_o:  'foo',
+        ba_r:   'bar',
+        baz:    'baz',
+        Ot_her: 'other'
+      }
+    end
+
+    it 'is stored as preferred if mentioned, otherwise as uncased' do
+      expect(subject.keys).to match_array [:foo, 'BAR', :b_a_z, 'other']
+    end
+  end
 end