Implement `-t' CLI option switch to specify target

spec/producer/core/cli_spec.rb

@@ -122,7 +122,7 @@ module Producer::Core
 
     describe '#parse_arguments!' do
       context 'with options' do
-        let(:options) { %w[-v] }
+        let(:options) { %w[-v -t some_host.example] }
 
         before { cli.parse_arguments! }
 
@@ -131,6 +131,8 @@ module Producer::Core
         end
 
         context 'verbose' do
+          let(:options) { %w[-v] }
+
           it 'enables env verbose mode' do
             expect(cli.env).to be_verbose
           end
@@ -143,6 +145,14 @@ module Producer::Core
             expect(cli.env).to be_dry_run
           end
         end
+
+        context 'target' do
+          let(:options) { %w[-t some_host.example] }
+
+          it 'assigns the given target to the env' do
+            expect(cli.env.target).to eq 'some_host.example'
+          end
+        end
       end
 
       context 'without arguments' do

spec/producer/core/recipe/dsl_spec.rb

@@ -65,9 +65,19 @@ module Producer::Core
       describe '#target' do
         let(:host) { 'some_host.example' }
 
-        it 'registers the target host in the env' do
-          dsl.target host
-          expect(env.target).to eq host
+        context 'when env has no assigned target' do
+          it 'registers the target host in the env' do
+            dsl.target host
+            expect(env.target).to eq host
+          end
+        end
+
+        context 'when env has an assigned target' do
+          before { env.target = 'already_assigned_host.example' }
+
+          it 'does not change env target' do
+            expect { dsl.target host }.not_to change { env.target }
+          end
         end
       end