Introduce CI/CD variables collection class

app/models/project_services/kubernetes_service.rb

@@ -100,19 +100,17 @@ class KubernetesService < DeploymentService
   def predefined_variables
     config = YAML.dump(kubeconfig)
 
-    variables = [
-      { key: 'KUBE_URL', value: api_url, public: true },
-      { key: 'KUBE_TOKEN', value: token, public: false },
-      { key: 'KUBE_NAMESPACE', value: actual_namespace, public: true },
-      { key: 'KUBECONFIG', value: config, public: false, file: true }
-    ]
-
-    if ca_pem.present?
-      variables << { key: 'KUBE_CA_PEM', value: ca_pem, public: true }
-      variables << { key: 'KUBE_CA_PEM_FILE', value: ca_pem, public: true, file: true }
+    variables = Gitlab::Ci::Variables::Collection.new.tap do |collection|
+      collection.append(key: 'KUBE_URL', value: api_url, public: true)
+      collection.append(key: 'KUBE_TOKEN', value: token, public: false)
+      collection.append(key: 'KUBE_NAMESPACE', value: actual_namespace, public: true)
+      collection.append(key: 'KUBECONFIG', value: config, public: false, file: true)
+
+      collection.append(key: 'KUBE_CA_PEM', value: ca_pem, public: true)
+      collection.append(key: 'KUBE_CA_PEM_FILE', value: ca_pem, public: true, file: true)
     end
 
-    variables
+    variables.to_hash
   end
 
   # Constructs a list of terminals from the reactive cache

lib/gitlab/ci/variables/collection.rb

+module Gitlab
+  module Ci
+    module Variables
+      class Collection
+        include Enumerable
+
+        Variable = Struct.new(:key, :value, :public, :file)
+
+        def initialize(variables = [])
+          @variables = []
+
+          variables.each { |variable| append(variable) }
+        end
+
+        def append(resource)
+          @variables.append(fabricate(resource))
+        end
+
+        def each
+          @variables.each { |variable| yield variable }
+        end
+
+        def +(other)
+          self.class.new.tap do |collection|
+            self.each { |variable| collection.append(variable) }
+            other.each { |variable| collection.append(variable) }
+          end
+        end
+
+        def to_h
+          self.map do |variable|
+            variable.to_h.reject do |key, value|
+              key == :file && value == false
+            end
+          end
+        end
+
+        alias_method :to_hash, :to_h
+
+        private
+
+        def fabricate(resource)
+          case resource
+          when Hash
+            Variable.new(resource.fetch(:key),
+                         resource.fetch(:value),
+                         resource.fetch(:public, false),
+                         resource.fetch(:file, false))
+          when ::Ci::Variable
+            Variable.new(resource.key, resource.value, false, false)
+          when Collection::Variable
+            resource.dup
+          else
+            raise ArgumentError, 'Unknown CI/CD variable resource!'
+          end
+        end
+      end
+    end
+  end
+end

spec/lib/gitlab/ci/variables/collection_spec.rb

+require 'spec_helper'
+
+describe Gitlab::Ci::Variables::Collection do
+  describe '.new' do
+    it 'can be initialized with an array' do
+      variable = { key: 'SOME_VAR', value: 'Some Value'}
+      collection = described_class.new([variable])
+
+      expect(collection.first.to_h).to include variable
+    end
+
+    it 'can be initialized without an argument' do
+      expect(subject).to be_none
+    end
+  end
+
+  describe '#append' do
+    it 'appends a hash' do
+      subject.append(key: 'VARIABLE', value: 'something')
+
+      expect(subject).to be_one
+    end
+
+    it 'appends a Ci::Variable' do
+      subject.append(build(:ci_variable))
+
+      expect(subject).to be_one
+    end
+
+    it 'appends an internal resource' do
+      collection = described_class.new([{ key: 'TEST', value: 1 }])
+
+      subject.append(collection.first)
+
+      expect(subject).to be_one
+    end
+  end
+
+  describe '#+' do
+    it 'makes it possible to combine with an array' do
+      collection = described_class.new([{ key: 'TEST', value: 1 }])
+      variables = [{ key: 'TEST', value: 'something'}]
+
+      expect((collection + variables).count).to eq 2
+    end
+
+    it 'makes it possible to combine with another collection' do
+      collection = described_class.new([{ key: 'TEST', value: 1 }])
+      other = described_class.new([{ key: 'TEST', value: 2 }])
+
+      expect((collection + other).count).to eq 2
+    end
+  end
+
+  describe '#to_hash' do
+    it 'creates a hash / value mapping' do
+      collection = described_class.new([{ key: 'TEST', value: 1 }])
+
+      expect(collection.to_hash)
+        .to eq [{ key: 'TEST', value: 1, public: false }]
+    end
+  end
+end