create XML coverage file without BOM (#1604)

* create XML coverge file without BOM

* incorporate review comments

* nit

---------

Co-authored-by: David Müller <[email protected]>

Author: Bertk

src/coverlet.core/Reporters/CoberturaReporter.cs

@@ -145,8 +145,9 @@ public string Report(CoverageResult result, ISourceRootTranslator sourceRootTran
       coverage.Add(packages);
       xml.Add(coverage);
 
-      var stream = new MemoryStream();
-      xml.Save(stream);
+      using var stream = new MemoryStream();
+      using var streamWriter = new StreamWriter(stream, new UTF8Encoding(false));
+      xml.Save(streamWriter);
 
       return Encoding.UTF8.GetString(stream.ToArray());
     }

src/coverlet.core/Reporters/OpenCoverReporter.cs

@@ -248,8 +248,9 @@ public string Report(CoverageResult result, ISourceRootTranslator sourceRootTran
       coverage.Add(modules);
       xml.Add(coverage);
 
-      var stream = new MemoryStream();
-      xml.Save(stream);
+      using var stream = new MemoryStream();
+      using var streamWriter = new StreamWriter(stream, new UTF8Encoding(false));
+      xml.Save(streamWriter);
 
       return Encoding.UTF8.GetString(stream.ToArray());
     }

test/coverlet.core.tests/Reporters/CoberturaReporterTests.cs

@@ -69,7 +69,7 @@ public void TestReport()
 
         Assert.NotEmpty(report);
 
-        var doc = XDocument.Load(new MemoryStream(Encoding.UTF8.GetBytes(report)));
+        var doc = XDocument.Load(new StringReader(report));
 
         IEnumerable<XAttribute> matchingRateAttributes = doc.Descendants().Attributes().Where(attr => attr.Name.LocalName.EndsWith("-rate"));
         IEnumerable<string> rateParentNodeNames = matchingRateAttributes.Select(attr => attr.Parent.Name.LocalName);
@@ -101,6 +101,24 @@ public void TestReport()
       }
     }
 
+    [Fact]
+    public void CoberturaTestReportDoesNotContainBom()
+    {
+      var result = new CoverageResult { Parameters = new CoverageParameters(), Identifier = Guid.NewGuid().ToString() };
+      var documents = new Documents();
+      var classes = new Classes { { "Class", new Methods() } };
+
+      documents.Add(RuntimeInformation.IsOSPlatform(OSPlatform.Windows) ? @"C:\doc.cs" : @"/doc.cs", classes);
+
+      result.Modules = new Modules { { "Module", documents } };
+
+      var reporter = new CoberturaReporter();
+      string report = reporter.Report(result, new Mock<ISourceRootTranslator>().Object);
+
+      byte[] preamble = Encoding.UTF8.GetBytes(report)[..3];
+      Assert.NotEqual(Encoding.UTF8.GetPreamble(), preamble);
+    }
+
     [Theory]
     [InlineData(
         "Test.SearchRequest::pb::Google.Protobuf.IMessage.get_Descriptor()",
@@ -151,7 +169,8 @@ public void TestEnsureParseMethodStringCorrectly(
 
       Assert.NotEmpty(report);
 
-      var doc = XDocument.Load(new MemoryStream(Encoding.UTF8.GetBytes(report)));
+      var doc = XDocument.Load(new StringReader(report));
+
       var methodAttrs = doc.Descendants()
           .Where(o => o.Name.LocalName == "method")
           .Attributes()
@@ -220,7 +239,7 @@ public void TestReportWithDifferentDirectories()
       var reporter = new CoberturaReporter();
       string report = reporter.Report(result, new Mock<ISourceRootTranslator>().Object);
 
-      var doc = XDocument.Load(new MemoryStream(Encoding.UTF8.GetBytes(report)));
+      var doc = XDocument.Load(new StringReader(report));
 
       var basePaths = doc.Element("coverage").Element("sources").Elements().Select(e => e.Value).ToList();
       var relativePaths = doc.Element("coverage").Element("packages").Element("package")
@@ -262,7 +281,8 @@ public void TestReportWithSourcelinkPaths()
       var reporter = new CoberturaReporter();
       string report = reporter.Report(result, new Mock<ISourceRootTranslator>().Object);
 
-      var doc = XDocument.Load(new MemoryStream(Encoding.UTF8.GetBytes(report)));
+      var doc = XDocument.Load(new StringReader(report));
+
       string fileName = doc.Element("coverage").Element("packages").Element("package").Element("classes").Elements()
           .Select(e => e.Attribute("filename").Value).Single();
 

test/coverlet.core.tests/Reporters/OpenCoverReporterTests.cs

@@ -27,7 +27,7 @@ public void TestReport()
       var reporter = new OpenCoverReporter();
       string report = reporter.Report(result, new Mock<ISourceRootTranslator>().Object);
       Assert.NotEmpty(report);
-      var doc = XDocument.Load(new MemoryStream(Encoding.UTF8.GetBytes(report)));
+      var doc = XDocument.Load(new StringReader(report));
       Assert.Empty(doc.Descendants().Attributes("sequenceCoverage").Where(v => v.Value != "33.33"));
       Assert.Empty(doc.Descendants().Attributes("branchCoverage").Where(v => v.Value != "25"));
       Assert.Empty(doc.Descendants().Attributes("nPathComplexity").Where(v => v.Value != "4"));
@@ -77,6 +77,22 @@ public void TestLineBranchCoverage()
       Assert.Contains(@"<SequencePoint vc=""1"" uspid=""4"" ordinal=""3"" sl=""4"" sc=""1"" el=""4"" ec=""2"" bec=""3"" bev=""2"" fileid=""1"" />", xml);
     }
 
+    [Fact]
+    public void OpenCoverTestReportDoesNotContainBom()
+    {
+      var result = new CoverageResult
+      {
+        Identifier = Guid.NewGuid().ToString(),
+        Modules = new Modules { { "Coverlet.Core.Reporters.Tests", CreateBranchCoverageDocuments() } },
+        Parameters = new CoverageParameters()
+      };
+
+      string report = new OpenCoverReporter().Report(result, new Mock<ISourceRootTranslator>().Object);
+
+      byte[] preamble = Encoding.UTF8.GetBytes(report)[..3];
+      Assert.NotEqual(Encoding.UTF8.GetPreamble(), preamble);
+    }
+
     private static Documents CreateFirstDocuments()
     {
       var lines = new Lines();