Fix self-closing XML element is not equivalent to an element without content

[lg2de]

While testing equivalence of XML documents using the XDocument/XElement extension of FA, I found that "empty elements" are identified as different to "self-closing elements", but e.g. <child></child> should be equivalent to <child />, e.g. according to https://www.w3schools.com/xml/xml_elements.asp

My proposed solution does not look great. But I did not have any other idea to "move forward" and "rewind" the XmlReader.

What do you think?

[jnyrup]

Thanks for taking a stab at this.
With all this conditional logic, the number of tests doesn't seem covering.
E.g. I was able to comment out both !otherReader.IsEmptyElement and && !otherReader.HasValue and all tests still passed.

[lg2de]

Thanks for taking a stab at this.
With all this conditional logic, the number of tests doesn't seem covering.
E.g. I was able to comment out both !otherReader.IsEmptyElement and && !otherReader.HasValue and all tests still passed.

I think, the conditions are required (logically).
I'll try to extend tests.

[jnyrup]

I tried to do some manual mutation testing to get a better gut feeling about the logic.
I wanted to verify that no condition can be omitted or negated.
All cases should have test catching the mutation.

The 6 cases marked with "no test" are the ones that didn't fail.

• 3 of those failed as expected when negating the condition instead of omitting, so I'm not concerned about those.
• It seems odd to me that the remaining 3 aren't caught by any tests.

By adding a test with both subject and expected being <parent><child></child></parent> we can kill two mutants. (Unless I messed something up during my testing)

this.reader.NodeType != XmlNodeType.EndElement

• omitting: no test
• mutate to ==: When_asserting_a_selfclosing_xml_element_is_equivalent_to_a_different_empty_xml_element_it_should_succeed

this.reader.LocalName != currentName

• omitting:
• mutate to ==: When_asserting_a_selfclosing_xml_element_is_equivalent_to_a_different_empty_xml_element_it_should_succeed

|| in MoveToEndElement

• mutate to &&: no test
• mutate to ^: When_asserting_an_xml_node_is_equivalent_to_different_xml_node_which_contains_extra_elements_it_should_fail_with_descriptive_message

if (subjectReader.IsEmptyElement && !otherReader.IsEmptyElement)

• mutate to otherReader.IsEmptyElement: When_asserting_a_selfclosing_xml_element_is_equivalent_to_a_different_empty_xml_element_it_should_succeed
• omitting !otherReader.IsEmptyElement: no test
• mutate to !subjectReader.IsEmptyElement: When_asserting_a_selfclosing_xml_element_is_equivalent_to_a_different_empty_xml_element_it_should_succeed
• omitting subjectReader.IsEmptyElement: subject: "<parent><child></child></parent>", expected: "<parent><child></child></parent>"
• remove entire condition: When_asserting_a_selfclosing_xml_element_is_equivalent_to_a_different_empty_xml_element_it_should_succeed

else if (otherReader.IsEmptyElement && !subjectReader.IsEmptyElement)

• mutate to subjectReader.IsEmptyElement: When_asserting_an_empty_xml_element_is_equivalent_to_a_different_selfclosing_xml_element_it_should_succeed
• omitting !subjectReader.IsEmptyElement: no test
• mutate to !otherReader.IsEmptyElement: When_asserting_an_empty_xml_element_is_equivalent_to_a_different_selfclosing_xml_element_it_should_succeed
• omitting otherReader.IsEmptyElement: subject: "<parent><child></child></parent>", expected: "<parent><child></child></parent>"
• remove entire condition: When_asserting_an_empty_xml_element_is_equivalent_to_a_different_selfclosing_xml_element_it_should_succeed

skipOnce = true; in MoveToEndElement()

• remove: When_asserting_an_xml_node_is_equivalent_to_different_xml_node_which_contains_extra_elements_it_should_fail_with_descriptive_message

reader.MoveToContent(); in MoveToEndElement()

• remove: no test

skipOnce = false; in Read()

• remove: no test

return true; in Read()

• remove: When_asserting_an_xml_node_is_equivalent_to_different_xml_node_which_contains_extra_elements_it_should_fail_with_descriptive_message

[dennisdoomen]

@jnyrup you don't have Netflix over there? 😂

[lg2de]

@jnyrup, I added two tests and removed a statement which is not really required.
So, I reduced the number of "surviving mutants".

There are left-overs due to skipOnce.
I have no idea so far to generate a user-level test (public API) to validate.
I tried to create tests directly on XmlReaderWrapper, but failed because internal classes cannot be tested currently in FA. :(

So, I kindly ask to take the current version. The wrapper may (!!!) not need the code when used only in XmlReaderValidator (in the current form). But it is required logically and will be required when it is reused in other parts of FA.

[jnyrup]

Looks good, great job 👍