Add Fields::Hash#each and make the Hash class an Enumerable

lib/rackstash/fields/hash.rb

@@ -10,6 +10,8 @@ require 'rackstash/fields/abstract_collection'
 module Rackstash
   module Fields
     class Hash < AbstractCollection
+      include ::Enumerable
+
       # @return [Set<String>] a frozen list of strings which are not allowed to
       #   be used as keys in this hash.
       attr_reader :forbidden_keys
@@ -224,6 +226,59 @@ module Rackstash
         merge!(hash, force: force, scope: scope, &resolver)
       end
 
+      # Calls the given block once for each key in the hash, passing the
+      # key-value pair as parameters.
+      #
+      # If no block is given, an `Enumerator` is returned instead.
+      #
+      # @yield [key, value] calls the given block once for each key in the hash
+      # @yieldparam key [String] the yielded key
+      # @yieldparam value [Object] the yielded value
+      # @return [Enumerator, self] `self` if a block was given or an
+      #   `Enumerator` if no block was given.
+      def each
+        return enum_for(__method__) unless block_given?
+        @raw.each_pair do |key, value|
+          yield key, value
+        end
+        self
+      end
+      alias each_pair each
+
+      # Calls the given block once for each key in the hash, passing the key as
+      # a parameter.
+      #
+      # If no block is given, an `Enumerator` is returned instead.
+      #
+      # @yield [key] calls the given block once for each key in the hash
+      # @yieldparam key [String] the yielded key
+      # @return [Enumerator, self] `self` if a block was given or an
+      #   `Enumerator` if no block was given.
+      def each_key
+        return enum_for(__method__) unless block_given?
+        @raw.each_key do |key|
+          yield key
+        end
+        self
+      end
+
+      # Calls the given block once for each key in the hash, passing the value
+      # at the respective key as a parameter.
+      #
+      # If no block is given, an `Enumerator` is returned instead.
+      #
+      # @yield [value] calls the given block once for each key in the hash
+      # @yieldparam value [Object] the yielded value of the key
+      # @return [Enumerator, self] `self` if a block was given or an
+      #   `Enumerator` if no block was given.
+      def each_value
+        return enum_for(__method__) unless block_given?
+        @raw.each_value do |value|
+          yield value
+        end
+        self
+      end
+
       # @return [Boolean] `true` if the Hash contains no ley-value pairs,
       #   `false` otherwise.
       def empty?

spec/rackstash/fields/hash_spec.rb

@@ -13,6 +13,12 @@ describe Rackstash::Fields::Hash do
   let(:forbidden_keys) { Set.new }
   let(:hash) { Rackstash::Fields::Hash.new(forbidden_keys: forbidden_keys) }
 
+  it 'is an Enumerable' do
+    expect(described_class).to be < Enumerable
+    expect(::Enumerable.public_instance_methods - hash.methods)
+      .to be_empty
+  end
+
   describe '#initialize' do
     it 'can be initialized without any arguments' do
       Rackstash::Fields::Hash.new
@@ -383,6 +389,71 @@ describe Rackstash::Fields::Hash do
     end
   end
 
+  describe '#each' do
+    it 'yields each key-value pair' do
+      hash['foo'] = 'string'
+      hash[:bar] = 42
+
+      expect { |b| hash.each(&b) }
+        .to yield_successive_args(['foo', 'string'], ['bar', 42])
+    end
+
+    it 'returns the hash if a block was provided' do
+      hash['foo'] = 'bar'
+      expect(hash.each {}).to equal hash
+    end
+
+    it 'returns an Enumerator if no block was provided' do
+      hash['foo'] = 'bar'
+      expect(hash.each).to be_instance_of Enumerator
+    end
+
+    it 'can use the alias #each_pair' do
+      expect(hash.method(:each_pair)).to eql hash.method(:each)
+    end
+  end
+
+  describe '#each_key' do
+    it 'yields each key' do
+      hash['foo'] = 'string'
+      hash[:bar] = 42
+
+      expect { |b| hash.each_key(&b) }
+        .to yield_successive_args('foo', 'bar')
+    end
+
+    it 'returns the hash if a block was provided' do
+      hash['foo'] = 'bar'
+      expect(hash.each_key {}).to equal hash
+    end
+
+    it 'returns an Enumerator if no block was provided' do
+      hash['foo'] = 'bar'
+      expect(hash.each_key).to be_instance_of Enumerator
+    end
+  end
+
+  describe '#each_value' do
+    it 'yields each value' do
+      hash['foo'] = 'string'
+      hash[:bar] = 42
+      hash['double'] = 'string'
+
+      expect { |b| hash.each_value(&b) }
+        .to yield_successive_args('string', 42, 'string')
+    end
+
+    it 'returns the hash if a block was provided' do
+      hash['foo'] = 'bar'
+      expect(hash.each_value {}).to equal hash
+    end
+
+    it 'returns an Enumerator if no block was provided' do
+      hash['foo'] = 'bar'
+      expect(hash.each_value).to be_instance_of Enumerator
+    end
+  end
+
   describe '#empty?' do
     it 'returns true of there are any fields' do
       expect(hash.empty?).to be true