diff --git a/CHANGELOG.md b/CHANGELOG.md
index b3ed0c6..ac63ed9 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -13,6 +13,13 @@
 - Setter method `TestCase.result` used to ignore values of invalid types. This method now throws a `ValueError` instead.
 - Method `xunit2.TestCase.add_rerun_result` has been renamed to `add_interim_result` result to better reflect class hierarchy
   of interim (rerun and flaky) results.
+- Methods `JUnitXml.fromfile`, `JUnitXml.fromstring`, `JUnitXml.fromroot` always return a `JUnitXml` instance.
+  Earlier versions return a `TestSuite` instance when the root of the file / string / element is a `<TestSuite>`.
+  A `JUnitXml` instance has already been returned by earlier versions when the root of the file / string / element is a `<TestSuites>`.
+
+  If you want to create a `TestSuite` instance from a `<TestSuite>` element, use
+
+    TestSuite.fromelem(elem)
 
 ## [3.1.2] - 2024-08-31
 ### Fixed
diff --git a/junitparser/junitparser.py b/junitparser/junitparser.py
index a91c6a0..a3a68f3 100644
--- a/junitparser/junitparser.py
+++ b/junitparser/junitparser.py
@@ -743,25 +743,26 @@ def update_statistics(self):
         self.time = round(time, 3)
 
     @classmethod
-    def fromroot(cls, root_elem: Element):
+    def fromroot(cls, root_elem: Element) -> "JUnitXml":
         """Construct JUnit objects from an elementTree root element."""
-        if root_elem.tag == "testsuites":
-            instance = cls()
-        elif root_elem.tag == "testsuite":
-            instance = cls.testsuite()
-        else:
+        instance = cls()
+        if root_elem.tag == "testsuite":
+            testsuite_element = root_elem
+            root_elem = testsuite_element.makeelement("testsuites", {})
+            root_elem.append(testsuite_element)
+        if not root_elem.tag == "testsuites":
             raise JUnitXmlError("Invalid format.")
         instance._elem = root_elem
         return instance
 
     @classmethod
-    def fromstring(cls, text: Union[str, bytes]):
+    def fromstring(cls, text: Union[str, bytes]) -> "JUnitXml":
         """Construct JUnit objects from an XML string (str or bytes)."""
         root_elem = etree.fromstring(text)  # nosec
         return cls.fromroot(root_elem)
 
     @classmethod
-    def fromfile(cls, file: Union[str, IO], parse_func=None):
+    def fromfile(cls, file: Union[str, IO], parse_func=None) -> "JUnitXml":
         """
         Construct JUnit objects from an XML file.
 
diff --git a/tests/test_fromfile.py b/tests/test_fromfile.py
index 31bcbee..605c39a 100644
--- a/tests/test_fromfile.py
+++ b/tests/test_fromfile.py
@@ -5,6 +5,7 @@
 from unittest import skipIf
 from junitparser import (
     TestCase,
+    TestSuite,
     Skipped,
     Failure,
     JUnitXmlError,
@@ -21,13 +22,19 @@
 
 def do_test_fromfile(fromfile_arg):
     xml = JUnitXml.fromfile(fromfile_arg)
+    assert isinstance(xml, JUnitXml)
     suite1, suite2 = list(iter(xml))
+    assert isinstance(suite1, TestSuite)
+    assert isinstance(suite2, TestSuite)
     assert len(list(suite1.properties())) == 0
     assert len(list(suite2.properties())) == 3
     assert len(suite2) == 3
     assert suite2.name == "JUnitXmlReporter.constructor"
     assert suite2.tests == 3
     cases = list(suite2.iterchildren(TestCase))
+    assert isinstance(cases[0], TestCase)
+    assert isinstance(cases[1], TestCase)
+    assert isinstance(cases[2], TestCase)
     assert isinstance(cases[0].result[0], Failure)
     assert isinstance(cases[1].result[0], Skipped)
     assert len(cases[2].result) == 0
@@ -98,13 +105,19 @@ def parse_func(file_path):
         os.path.join(os.path.dirname(__file__), "data/normal.xml"),
         parse_func=parse_func,
     )
+    assert isinstance(xml, JUnitXml)
     suite1, suite2 = list(iter(xml))
+    assert isinstance(suite1, TestSuite)
+    assert isinstance(suite2, TestSuite)
     assert len(list(suite1.properties())) == 0
     assert len(list(suite2.properties())) == 3
     assert len(suite2) == 3
     assert suite2.name == "JUnitXmlReporter.constructor"
     assert suite2.tests == 3
     cases = list(suite2.iterchildren(TestCase))
+    assert isinstance(cases[0], TestCase)
+    assert isinstance(cases[1], TestCase)
+    assert isinstance(cases[2], TestCase)
     assert isinstance(cases[0].result[0], Failure)
     assert isinstance(cases[1].result[0], Skipped)
     assert len(cases[2].result) == 0
@@ -114,20 +127,31 @@ def test_fromfile_without_testsuites_tag():
     xml = JUnitXml.fromfile(
         os.path.join(os.path.dirname(__file__), "data/no_suites_tag.xml")
     )
-    cases = list(iter(xml))
-    properties = list(iter(xml.properties()))
-    assert len(properties) == 3
+    assert isinstance(xml, JUnitXml)
+    suites = list(iter(xml))
+    assert len(suites) == 1
+    suite = suites[0]
+    assert isinstance(suite, TestSuite)
+    assert suite.name == "JUnitXmlReporter.constructor"
+    assert suite.tests == 3
+    cases = list(iter(suite))
     assert len(cases) == 3
-    assert xml.name == "JUnitXmlReporter.constructor"
-    assert xml.tests == 3
+    assert isinstance(cases[0], TestCase)
+    assert isinstance(cases[1], TestCase)
+    assert isinstance(cases[2], TestCase)
     assert isinstance(cases[0].result[0], Failure)
     assert isinstance(cases[1].result[0], Skipped)
     assert len(cases[2].result) == 0
+    properties = list(iter(suite.properties()))
+    assert len(properties) == 3
 
 
 def test_fromfile_with_testsuite_in_testsuite():
     xml = JUnitXml.fromfile(os.path.join(os.path.dirname(__file__), "data/jenkins.xml"))
+    assert isinstance(xml, JUnitXml)
     suite1, suite2 = list(iter(xml))
+    assert isinstance(suite1, TestSuite)
+    assert isinstance(suite2, TestSuite)
     assert len(list(suite1.properties())) == 0
     assert len(list(suite2.properties())) == 3
     assert len(suite2) == 3
@@ -135,8 +159,11 @@ def test_fromfile_with_testsuite_in_testsuite():
     assert suite2.tests == 3
     direct_cases = list(suite2.iterchildren(TestCase))
     assert len(direct_cases) == 1
+    assert isinstance(direct_cases[0], TestCase)
     assert isinstance(direct_cases[0].result[0], Failure)
     all_cases = list(suite2)
+    assert isinstance(all_cases[0], TestCase)
+    assert isinstance(all_cases[1], TestCase)
     assert isinstance(all_cases[0].result[0], Failure)
     assert isinstance(all_cases[1].result[0], Skipped)
     assert len(all_cases[2].result) == 0
@@ -167,6 +194,9 @@ def test_multi_results_in_case():
    </testsuite>
 </testsuites>"""
     xml = JUnitXml.fromstring(text)
+    assert isinstance(xml, JUnitXml)
     suite = next(iter(xml))
+    assert isinstance(suite, TestSuite)
     case = next(iter(suite))
+    assert isinstance(case, TestCase)
     assert len(case.result) == 2
diff --git a/tests/test_general.py b/tests/test_general.py
index d5ea93e..6f650d3 100644
--- a/tests/test_general.py
+++ b/tests/test_general.py
@@ -127,6 +127,7 @@ def test_fromstring(self):
         <testcase name="testname2">
         </testcase></testsuite></testsuites>"""
         result = JUnitXml.fromstring(text)
+        assert isinstance(result, JUnitXml)
         assert len(result) == 2
         assert result.time == 0
 
@@ -135,6 +136,7 @@ def test_fromstring_no_testsuites(self):
         <testcase name="testname1">
         </testcase></testsuite>"""
         result = JUnitXml.fromstring(text)
+        assert isinstance(result, JUnitXml)
         assert len(result) == 1
         assert result.time == 0
 
@@ -178,10 +180,14 @@ def test_fromroot_testsuite(self):
         </testsuite>"""
         root_elemt = etree.fromstring(text)
         result = JUnitXml.fromroot(root_elemt)
-        assert isinstance(result, TestSuite)
-        assert result.errors == 1
-        assert result.skipped == 1
-        cases = list(iter(result))
+        assert isinstance(result, JUnitXml)
+        suites = list(iter(result))
+        assert len(suites) == 1
+        suite = suites[0]
+        assert isinstance(suite, TestSuite)
+        assert suite.errors == 1
+        assert suite.skipped == 1
+        cases = list(iter(suite))
         assert len(cases[0].result) == 0
         assert len(cases[1].result) == 2
         text = cases[1].result[1].text
@@ -203,6 +209,7 @@ def test_fromroot_testsuites(self):
         </testsuites>"""
         root_elemt = etree.fromstring(text)
         result = JUnitXml.fromroot(root_elemt)
+        assert isinstance(result, JUnitXml)
         assert result.errors == 1
         assert result.skipped == 1
         suite = list(iter(result))[0]
diff --git a/tests/test_write.py b/tests/test_write.py
index add40a5..ab55a25 100644
--- a/tests/test_write.py
+++ b/tests/test_write.py
@@ -22,7 +22,7 @@
 python_minor = int(sys.version.split(".")[1])
 
 
-def get_expected_xml(test_case_name: str, test_suites: bool = True):
+def get_expected_xml(test_case_name: str, test_suites: bool = True, newlines: bool = False):
     if python_major == 3 and python_minor <= 7 and not has_lxml:
         expected_test_suite = '<testsuite errors="0" failures="0" name="suite1" skipped="0" tests="1" time="0">'
     else:
@@ -42,9 +42,13 @@ def get_expected_xml(test_case_name: str, test_suites: bool = True):
         start_test_suites = ""
         end_test_suites = ""
 
+    eol = "\n" if newlines else ""
+    indent = " " if newlines else ""
     return (
         f"<?xml version='1.0' encoding='{encoding}'?>\n"
-        f'{start_test_suites}{expected_test_suite}<testcase name="{test_case_name}"{closing_tag}></testsuite>{end_test_suites}'
+        f'{start_test_suites}{expected_test_suite}{eol}'
+        f'{indent}<testcase name="{test_case_name}"{closing_tag}>{eol}'
+        f'</testsuite>{end_test_suites}'
     )
 
 
@@ -174,6 +178,31 @@ def test_write_nonascii():
     assert xmlfile.getvalue().decode("utf-8") == get_expected_xml("用例1")
 
 
+def test_write_no_testsuites():
+    # Has to be a binary string to include xml declarations.
+    text = b"""<?xml version='1.0' encoding='UTF-8'?>
+<testsuite name="suite1" tests="1" errors="0" failures="0" skipped="0" time="0">
+ <testcase name="case1"/>
+</testsuite>"""
+    xml = JUnitXml.fromstring(text)
+    assert isinstance(xml, JUnitXml)
+    suite = next(iter(xml))
+    assert isinstance(suite, TestSuite)
+    case = next(iter(suite))
+    assert isinstance(case, TestCase)
+    assert len(case.result) == 0
+
+    # writing this JUnitXml object contains a root <testsuites> element
+    xmlfile = BytesIO()
+    xml.write(xmlfile)
+    assert xmlfile.getvalue().decode("utf-8") == get_expected_xml("case1", test_suites=True, newlines=True)
+
+    # writing the inner testsuite reproduces the input string
+    xmlfile = BytesIO()
+    suite.write(xmlfile)
+    assert xmlfile.getvalue().decode("utf-8") == get_expected_xml("case1", test_suites=False, newlines=True)
+
+
 def test_read_written_xml():
     suite1 = TestSuite()
     suite1.name = "suite1"
diff --git a/tests/test_xunit2.py b/tests/test_xunit2.py
index 6499a52..3621bbc 100644
--- a/tests/test_xunit2.py
+++ b/tests/test_xunit2.py
@@ -211,7 +211,11 @@ def test_suite_fromstring(self):
          <testcase name="test name 1"/>
          <testcase name="test name 2"/>
         </testsuite>"""
-        suite = JUnitXml.fromstring(text)
+        xml = JUnitXml.fromstring(text)
+        assert isinstance(xml, JUnitXml)
+        suites = list(xml)
+        assert len(suites) == 1
+        suite = suites[0]
         assert isinstance(suite, TestSuite)
         assert suite.name == "suite name"
         cases = list(suite)