Fix XmlException when writing Html log with certain test names

[danmoseley]

Fix #3136

Bug: In the repro case, the test metadata (display name here) contains characters like  that are not valid in XML (outside of CDATA perhaps) per spec:

https://www.w3.org/TR/2008/REC-xml-20081126/#NT-Char

[2]	Char	::=	#x9 | #xA | #xD | [#x20-#xD7FF] | [#xE000-#xFFFD] | [#x10000-#x10FFFF]	/* any Unicode character, excluding the surrogate blocks, FFFE, and FFFF. */

The HtmlLogger serializes the TestResult to XML using DCS. DCS is tolerant of these invalid characters -- it will serialize as eg  and read that too. XmlTextWriter will by default serialize the same way. But in default configuration XmlReader will not read it, and throw XmlException causing the production of the Html log to fail.

Fix: set XmlWriterSettings.CheckCharacters to false.

I verified that this fixes the problem locally. I tried hard to make a unit test (see first commit) but concluded that it's not mockable using public API: HtmlTransformer is internal. I guess it could be mocked using reflection or we could use an end to end test instead? I don't have more time to spend, so perhaps it's acceptable without a test.

[danmoseley]

compare lines in original code:
https://github.com/dotnet/runtime/blob/b00ebc853fdb46425842cf6cae8186d65031e9ef/src/libraries/System.Private.Xml/src/System/Xml/Xslt/XslCompiledTransform.cs#L365-L366

was calling

        public void Transform(string inputUri, string resultsFile)
        {
            ArgumentNullException.ThrowIfNull(inputUri);
            ArgumentNullException.ThrowIfNull(resultsFile);

            // SQLBUDT 276415: Prevent wiping out the content of the input file if the output file is the same
            using XmlReader reader = XmlReader.Create(inputUri);
            using XmlWriter writer = XmlWriter.Create(resultsFile, OutputSettings);
            Transform(reader, null, writer, CreateDefaultResolver());

now calling

        public void Transform(XmlReader input, XmlWriter results)
        {
            ArgumentNullException.ThrowIfNull(input);
            ArgumentNullException.ThrowIfNull(results);

            Transform(input, null, results, CreateDefaultResolver());
        }

I believe OutputSettings above was null.

[nohwnd]

Thanks, will have a look tomorrow.

[danmoseley]

in case it's useful in future, here's the half attempt I had at a test, that I gave up on

-    [TestMethod]
-    public void TestCompleteHandlerShouldHandleInvalidCharReferences()
-    {
-        VisualStudio.TestPlatform.Extensions.HtmlLogger.HtmlLogger hl = new(_mockFileHelper.Object, new Mock<IHtmlTransformer>().Object, new DataContractSerializer(typeof(TestRunDetails)));
-        hl.Initialize(_events.Object, _parameters);
-
-        MemoryStream xmlStream = new();
-        _mockFileHelper.Setup(x => x.GetStream(It.IsAny<string>(), FileMode.Open, FileAccess.Read)).Returns(xmlStream);
-        _mockFileHelper.Setup(x => x.Exists(It.IsAny<string>())).Returns(false);
-
-        MemoryStream htmlStream = new();
-        _mockFileHelper.Setup(x => x.GetStream(It.IsAny<string>(), FileMode.OpenOrCreate, FileAccess.ReadWrite)).Returns(htmlStream);
-        _mockFileHelper.Setup(x => x.Exists(It.IsAny<string>())).Returns(false);
-
-        var testCase = new TestCase("TestName", new Uri("some://uri"), "TestSource");
-        var testResult = new ObjectModel.TestResult(testCase) { Outcome = TestOutcome.Failed };
-        testResult.Messages.Add(new(TestResultMessage.StandardErrorCategory, "\uFFFF"));
-
-        hl.TestResultHandler(new object(), new TestResultEventArgs(testResult));
-
-        hl.TestRunCompleteHandler(new object(), new TestRunCompleteEventArgs(null, false, true, null, null, null, TimeSpan.Zero));
-
-        //Assert.AreEqual(htmlFileContent, new StreamReader(htmlStream).ReadToEnd());
-    }