fix tests

src/lib/y2partitioner/setup_errors_presenter.rb

@@ -44,7 +44,7 @@ def initialize(setup_checker)
     #
     # @return [String]
     def to_html
-      errors_html || warnings_html || nil
+      errors_html || warnings_html || ""
     end
 
   private

test/y2storage/boot_requirements_errors_test.rb

@@ -103,7 +103,7 @@
         expect(checker.errors).to all(be_a(Y2Storage::SetupError))
 
         message = checker.errors.first.message
-        expect(message).to match(/no device mounted to '\/'/)
+        expect(message).to match(/no device mounted at '\/'/)
       end
     end
 
@@ -406,7 +406,18 @@
         context "with a partitions-based proposal" do
           let(:use_lvm) { false }
 
-          include_examples "PReP partition"
+          context "and there is no a PReP partition in the system" do
+            let(:partitions) { [boot_partition] }
+            include_examples "missing prep partition"
+          end
+
+          context "and there is a PReP partition in the system" do
+            let(:partitions) { [boot_partition, prep_partition] }
+
+            it "does not contain errors" do
+              expect(checker.warnings).to be_empty
+            end
+          end
         end
 
         context "with a LVM-based proposal" do