Add a MockSource for the resolver tests

spec/unit/resolver_spec.rb

@@ -13,6 +13,68 @@ end
 
 module Pod
   describe Resolver do
+    class MockSource < Source
+      attr_reader :name
+
+      def initialize(name, &blk)
+        @name = name
+        @_pods_by_name = Hash.new { |h, k| h[k] = [] }
+        @_current_pod = nil
+        instance_eval(&blk)
+        super('/mock/repo')
+      end
+
+      def pod(name, version = nil, platform: [[:ios, '9.0']], test_spec: false, &_blk)
+        cp = @_current_pod
+        Pod::Specification.new(cp, name, test_spec) do |spec|
+          @_current_pod = spec
+          if cp
+            cp.subspecs << spec
+          else
+            spec.version = version
+          end
+          platform.each { |pl, dt| spec.send(pl).deployment_target = dt }
+          yield spec if block_given?
+        end
+        @_pods_by_name[name] << @_current_pod if cp.nil?
+      ensure
+        @_current_pod = cp
+      end
+
+      def test_spec(name: 'Tests', &blk)
+        pod(name, :test_spec => true, &blk)
+      end
+
+      def all_specs
+        @_pods_by_name.values.flatten(1)
+      end
+
+      def pods
+        @_pods_by_name.keys
+      end
+
+      def search(query)
+        query = query.root_name if query.is_a?(Dependency)
+        set(query) if @_pods_by_name.key?(query)
+      end
+
+      def specification(name, version)
+        @_pods_by_name[name].find { |s| s.version == Pod::Version.new(version) }
+      end
+
+      def versions(name)
+        @_pods_by_name[name].map(&:version)
+      end
+
+      def specification_path(name, version)
+        pod_path(name).join(version.to_s, "#{name}.podspec")
+      end
+
+      def specs_dir
+        repo
+      end
+    end
+
     describe 'In general' do
       before do
         @podfile = Podfile.new do