Add spec tests for hiera_merge

Test for hiera_merge set to an invalid type that is not checked in the
code's case statement. Also test for error message returned from
validate_re().

spec/classes/init_spec.rb

@@ -842,8 +842,8 @@
   end
 
   describe 'with hiera_merge parameter specified' do
-    context 'as a non-boolean' do
-      let(:params) { { :hiera_merge => 'not_a_boolean' } }
+    context 'as a non-boolean or non-string' do
+      let(:params) { { :hiera_merge => ['not_a_boolean','or_a_string'] } }
       let(:facts) do
         { :osfamily          => 'RedHat',
           :lsbmajdistrelease => '6',
@@ -855,6 +855,19 @@
       end
     end
 
+    context 'as an invalid string' do
+      let(:params) { { :hiera_merge => 'invalid_string' } }
+      let(:facts) do
+        { :osfamily          => 'RedHat',
+          :lsbmajdistrelease => '6',
+        }
+      end
+
+      it 'should fail' do
+        expect { should raise_error(Puppet::Error,/^ssh::hiera_merge may be either 'true' or 'false' and is set to <invalid_string>./) }
+      end
+    end
+
     ['true',true].each do |value|
       context "as #{value}" do
         let(:params) { { :hiera_merge => value } }