Improve testing on inputs that do not have values (#4007)

Improve testing on inputs that do not have values

test/functional/inputs_test.rb

@@ -107,4 +107,14 @@ describe 'inputs' do
       end
     end
   end
+
+  describe 'when using a profile with undeclared (valueless) inputs' do
+    it 'should warn about them and not abort the run' do
+      cmd = "exec #{inputs_profiles_path}/undeclared"
+      result = run_inspec_process(cmd, json: true)
+      result.stderr.must_include "WARN: Input 'undeclared_01'"
+      result.stderr.must_include 'does not have a value'
+      result.must_have_all_controls_passing
+    end
+  end
 end

test/unit/mock/profiles/inputs/undeclared/controls/undeclared.rb

@@ -0,0 +1,28 @@
+control 'start_marker' do
+  describe('dummy_test_01') do
+    it { should cmp 'dummy_test_01'}
+  end
+end
+
+control 'undeclared_in_control_body' do
+  attribute('undeclared_01')
+  assignment_outcome = attribute('undeclared_02')
+  describe('dummy_test_02') do
+    it { should cmp 'dummy_test_02'}
+  end
+end
+
+control 'undeclared_in_only_if' do
+  only_if { attribute('undeclared_03') }
+  describe('dummy_test_03') do
+    it { should cmp 'dummy_test_03'}
+  end
+end
+
+attribute('undeclared_04')
+
+control 'end_marker' do
+  describe('dummy_test_04') do
+    it { should cmp 'dummy_test_04'}
+  end
+end

test/unit/mock/profiles/inputs/undeclared/inspec.yml

@@ -0,0 +1,8 @@
+name: undeclared_attribute
+title: InSpec Profile
+maintainer: The Authors
+copyright: The Authors
+copyright_email: you@example.com
+license: Apache-2.0
+summary: A profile mentioning an attribute in a control file that has not otherwise been mentioned
+version: 0.1.0