Fix the expected result of expr1

[ndw]

This is the test that will not rest.

I believe we've agreed that the result of this test should be an error. However, the test catalog currently asserts that it is "not a grammar". I don't think that's correct. This PR changes it to "not a sentence" which is better.

The description of the test suggests that we may need a new assertion. Perhaps that would be best. We could add, for example, assert-not-xml. If anyone thinks that's substantially better, just say so.

@cmsmcq I think you're the de facto maintainer of the test schemas, but if it's more convenient, I can make the change and send you a PR for the schemas.

[cmsmcq]

For what it's worth, I think the correct expectation for this test is assert-dynamic-error. The entry in the copy of this test catalog I am using reads:

  <test-case name="expr1">
    <created by="SP" on="2021-12-16"/>
    <modified by="MSM" on="2021-12-23"
              change="Change result"/>
    <modified by="MSM" on="2022-01-01"
              change="remove trailing whitespace from input"/>
    <modified by="MSM" on="2022-01-01"
              change="remove whitespace from expected result"/>
    <modified by="MSM" on="2022-05-21"
              change="change to assert-dynamic-error"/>
    <test-string-ref href="expr1.inp"/>
    <description>
      <p>Illustrates the way to handle dynamic errors in a test:
      use assert-dynamic-error.</p>
      <p>It's not formally a grammar error, since this grammar
      will work fine for some inputs and processors are not
      required to reject the grammar.  So assert-not-a-grammar
      is not the right thing.</p>
      <p>It's not formally a failure to parse the input, since
      this input string is perfectly grammatical against this
      input grammar.  So assert-not-a-sentence is not the right
      thing.</p>
      <p>The error arises in serialization and only at run time.
      So assert-dynamic-error.</p>
    </description>
    <result>
      <assert-dynamic-error/>
      <!--
      <assert-xml-ref href="expr1.output.xml"/>
      -->
    </result>
  </test-case>

In due course (I hope in the course of today) I will formulate a pull request to make this change.

[ndw]

That works for me. Thank you, Michael.

[yamahito]

Agree with Michael

[ndw]

Resolved by a recent merge, as described above.