new --refresh-parameters flag for update (#212)

Adds a new --refresh-parameters flag for update calls allowing stacks
to refresh parent stack parameters if necessary

lib/moonshot/commands/update.rb

@@ -18,11 +18,15 @@ def parser
         parser.on('--force', '-f', TrueClass, 'Apply ChangeSet without confirmation') do |v|
           @force = v
         end
+
+        parser.on('--refresh-parameters', TrueClass, 'Update parameters from parent stacks') do |v|
+          @refresh_parameters = v
+        end
       end
 
       def execute
         @force = true unless Moonshot.config.interactive
-        controller.update(dry_run: @dry_run, force: @force)
+        controller.update(dry_run: @dry_run, force: @force, refresh_parameters: @refresh_parameters)
       end
     end
   end

lib/moonshot/controller.rb

@@ -63,7 +63,7 @@ def create # rubocop:disable AbcSize
       end
     end
 
-    def update(dry_run:, force:) # rubocop:disable AbcSize
+    def update(dry_run:, force:, refresh_parameters:) # rubocop:disable AbcSize
       # Scan the template for all required parameters and configure
       # the ParameterCollection.
       @config.parameters = ParameterCollection.from_template(stack.template)
@@ -75,7 +75,8 @@ def update(dry_run:, force:) # rubocop:disable AbcSize
 
       # Import all Outputs from parent stacks as Parameters on this
       # stack.
-      ParentStackParameterLoader.new(@config).load_missing_only!
+      parent_stack_params = ParentStackParameterLoader.new(@config)
+      refresh_parameters ? parent_stack_params.load! : parent_stack_params.load_missing_only!
 
       # If there is an answer file, use it to populate parameters.
       if @config.answer_file
@@ -91,9 +92,7 @@ def update(dry_run:, force:) # rubocop:disable AbcSize
 
       # Interview the user for missing parameters, using the
       # appropriate prompts.
-      @config.parameters.values.each do |sp|
-        next if sp.set?
-
+      @config.parameters.values.reject(&:set?).each do |sp|
         parameter_source = @config.parameter_sources.fetch(sp.name,
                                                            @config.default_parameter_source)
         parameter_source.get(sp)

spec/moonshot/controller_spec.rb

@@ -153,8 +153,7 @@
       }
       expect(stack).to receive(:parameters).and_return(existing_parameters)
       expect(stack).to receive(:update)
-
-      subject.update(dry_run: false, force: false)
+      subject.update(dry_run: false, force: false, refresh_parameters: false)
 
       pc = subject.config.parameters
       expect(pc.keys).to eq(%w(InputParameter1 InputParameter2 InputParameter3 InputParameter4))
@@ -168,4 +167,29 @@
       expect(pc.values.map(&:to_cf)).to eq(expected_update_stack_parameters)
     end
   end
+
+  context 'when refresh-parameters option is provided' do
+    before(:each) do
+      subject.config.answer_file = fixture_path('answer2.yml')
+      subject.config.parameter_overrides['InputParameter4'] = 'Override4'
+
+      existing_parameters = {
+        'InputParameter1' => 'Existing1',
+        'InputParameter2' => 'Existing2',
+        'InputParameter3' => 'Existing3'
+      }
+      expect(stack).to receive(:parameters).and_return(existing_parameters)
+      expect(stack).to receive(:update)
+    end
+
+    it 'should preserve existing existing parent parameters' do
+      expect_any_instance_of(Moonshot::ParentStackParameterLoader).to receive(:load_missing_only!)
+      subject.update(dry_run: false, force: false, refresh_parameters: false)
+    end
+
+    it 'should refresh all parent stack parameters' do
+      expect_any_instance_of(Moonshot::ParentStackParameterLoader).to receive(:load!)
+      subject.update(dry_run: false, force: false, refresh_parameters: true)
+    end
+  end
 end