Implement `has_env' condition keyword

spec/producer/core/tests/has_env_spec.rb

@@ -0,0 +1,41 @@
+require 'spec_helper'
+
+module Producer::Core
+  describe Tests::HasEnv do
+    let(:env)           { Env.new }
+    let(:variable_name) { :some_variable_name }
+    subject(:has_env)   { Tests::HasEnv.new(env, variable_name) }
+
+    it 'is a kind of test' do
+      expect(has_env).to be_a Test
+    end
+
+    describe '#success?' do
+      let(:environment) { double('environment') }
+
+      before do
+        allow(env.remote).to receive(:environment) { environment }
+      end
+
+      it 'stringifies the queried variable name' do
+        expect(environment).to receive(:has_key?).with(kind_of(String))
+        has_env.success?
+      end
+
+      it 'upcases the queried variable name' do
+        expect(environment).to receive(:has_key?).with('SOME_VARIABLE_NAME')
+        has_env.success?
+      end
+
+      it 'returns true when remote environment var is defined' do
+        allow(environment).to receive(:has_key?) { true }
+        expect(has_env.success?).to be true
+      end
+
+      it 'returns false when remote environment var is not defined' do
+        allow(environment).to receive(:has_key?) { false }
+        expect(has_env.success?).to be false
+      end
+    end
+  end
+end