fix: generate xml report packages correctly on windows (#1574)

* fix: generate xml report packages correctly on windows

* test: check duplicate package names in xml report

* fix: shorten long line in test_xml

coverage/xmlreport.py

@@ -182,7 +182,7 @@ def xml_file(self, fr: FileReporter, analysis: Analysis, has_arcs: bool) -> None
                 rel_name = filename[len(source_path)+1:]
                 break
         else:
-            rel_name = fr.relative_filename()
+            rel_name = fr.relative_filename().replace("\\", "/")
             self.source_paths.add(fr.filename[:-len(rel_name)].rstrip(r"\/"))
 
         dirname = os.path.dirname(rel_name) or "."

tests/test_xml.py

@@ -318,6 +318,39 @@ def test_accented_directory(self) -> None:
             "name": "â",
         }
 
+    def test_no_duplicate_packages(self) -> None:
+        self.make_file(
+            "namespace/package/__init__.py", 
+            "from . import sample; from . import test; from .subpackage import test"
+        )
+        self.make_file("namespace/package/sample.py", "print('package.sample')")
+        self.make_file("namespace/package/test.py", "print('package.test')")
+        self.make_file("namespace/package/subpackage/test.py", "print('package.subpackage.test')")
+
+        # no source path passed to coverage!
+        # problem occurs when they are dynamically generated during xml report
+        cov = coverage.Coverage()
+
+        cov.start()
+        import_local_file("foo", "namespace/package/__init__.py")               # pragma: nested
+        cov.stop()                                                              # pragma: nested
+
+        cov.xml_report()
+
+        dom = ElementTree.parse("coverage.xml")
+
+        # only two packages should be present
+        packages = dom.findall(".//package")
+        assert len(packages) == 2
+
+        # one of them is namespace.package
+        named_package = dom.findall(".//package[@name='namespace.package']")
+        assert len(named_package) == 1
+
+        # the other one namespace.package.subpackage
+        named_sub_package = dom.findall(".//package[@name='namespace.package.subpackage']")
+        assert len(named_sub_package) == 1
+
 
 def unbackslash(v: Any) -> Any:
     """Find strings in `v`, and replace backslashes with slashes throughout."""