diff --git a/pandas/tests/io/test_pickle.py b/pandas/tests/io/test_pickle.py
index afc271264edbf..890146f0789ae 100644
--- a/pandas/tests/io/test_pickle.py
+++ b/pandas/tests/io/test_pickle.py
@@ -23,13 +23,14 @@
 from warnings import catch_warnings, simplefilter
 import zipfile
 
+import numpy as np
 import pytest
 
 from pandas.compat import PY38, get_lzma_file, import_lzma, is_platform_little_endian
 import pandas.util._test_decorators as td
 
 import pandas as pd
-from pandas import Index
+from pandas import Index, Series, period_range
 import pandas._testing as tm
 
 from pandas.tseries.offsets import Day, MonthEnd
@@ -499,7 +500,7 @@ def __init__(self):
 
 def test_read_pickle_with_subclass():
     # GH 12163
-    expected = pd.Series(dtype=object), MyTz()
+    expected = Series(dtype=object), MyTz()
     result = tm.round_trip_pickle(expected)
 
     tm.assert_series_equal(result[0], expected[0])
@@ -548,3 +549,25 @@ def _test_roundtrip(frame):
     _test_roundtrip(frame.T)
     _test_roundtrip(ymd)
     _test_roundtrip(ymd.T)
+
+
+def test_pickle_timeseries_periodindex():
+    # GH#2891
+    prng = period_range("1/1/2011", "1/1/2012", freq="M")
+    ts = Series(np.random.randn(len(prng)), prng)
+    new_ts = tm.round_trip_pickle(ts)
+    assert new_ts.index.freq == "M"
+
+
+@pytest.mark.parametrize(
+    "name", [777, 777.0, "name", datetime.datetime(2001, 11, 11), (1, 2)]
+)
+def test_pickle_preserve_name(name):
+    def _pickle_roundtrip_name(obj):
+        with tm.ensure_clean() as path:
+            obj.to_pickle(path)
+            unpickled = pd.read_pickle(path)
+        return unpickled
+
+    unpickled = _pickle_roundtrip_name(tm.makeTimeSeries(name=name))
+    assert unpickled.name == name
diff --git a/pandas/tests/series/test_io.py b/pandas/tests/series/methods/test_to_csv.py
similarity index 75%
rename from pandas/tests/series/test_io.py
rename to pandas/tests/series/methods/test_to_csv.py
index b12ebd58e6a7b..a72e860340f25 100644
--- a/pandas/tests/series/test_io.py
+++ b/pandas/tests/series/methods/test_to_csv.py
@@ -5,7 +5,7 @@
 import pytest
 
 import pandas as pd
-from pandas import DataFrame, Series
+from pandas import Series
 import pandas._testing as tm
 
 from pandas.io.common import get_handle
@@ -180,62 +180,3 @@ def test_to_csv_interval_index(self):
             expected.index = expected.index.astype(str)
 
             tm.assert_series_equal(result, expected)
-
-
-class TestSeriesIO:
-    def test_to_frame(self, datetime_series):
-        datetime_series.name = None
-        rs = datetime_series.to_frame()
-        xp = pd.DataFrame(datetime_series.values, index=datetime_series.index)
-        tm.assert_frame_equal(rs, xp)
-
-        datetime_series.name = "testname"
-        rs = datetime_series.to_frame()
-        xp = pd.DataFrame(
-            dict(testname=datetime_series.values), index=datetime_series.index
-        )
-        tm.assert_frame_equal(rs, xp)
-
-        rs = datetime_series.to_frame(name="testdifferent")
-        xp = pd.DataFrame(
-            dict(testdifferent=datetime_series.values), index=datetime_series.index
-        )
-        tm.assert_frame_equal(rs, xp)
-
-    def test_timeseries_periodindex(self):
-        # GH2891
-        from pandas import period_range
-
-        prng = period_range("1/1/2011", "1/1/2012", freq="M")
-        ts = Series(np.random.randn(len(prng)), prng)
-        new_ts = tm.round_trip_pickle(ts)
-        assert new_ts.index.freq == "M"
-
-    def test_pickle_preserve_name(self):
-        for n in [777, 777.0, "name", datetime(2001, 11, 11), (1, 2)]:
-            unpickled = self._pickle_roundtrip_name(tm.makeTimeSeries(name=n))
-            assert unpickled.name == n
-
-    def _pickle_roundtrip_name(self, obj):
-
-        with tm.ensure_clean() as path:
-            obj.to_pickle(path)
-            unpickled = pd.read_pickle(path)
-            return unpickled
-
-    def test_to_frame_expanddim(self):
-        # GH 9762
-
-        class SubclassedSeries(Series):
-            @property
-            def _constructor_expanddim(self):
-                return SubclassedFrame
-
-        class SubclassedFrame(DataFrame):
-            pass
-
-        s = SubclassedSeries([1, 2, 3], name="X")
-        result = s.to_frame()
-        assert isinstance(result, SubclassedFrame)
-        expected = SubclassedFrame({"X": [1, 2, 3]})
-        tm.assert_frame_equal(result, expected)
diff --git a/pandas/tests/series/methods/test_to_frame.py b/pandas/tests/series/methods/test_to_frame.py
new file mode 100644
index 0000000000000..b324fab5d97d4
--- /dev/null
+++ b/pandas/tests/series/methods/test_to_frame.py
@@ -0,0 +1,40 @@
+from pandas import DataFrame, Series
+import pandas._testing as tm
+
+
+class TestToFrame:
+    def test_to_frame(self, datetime_series):
+        datetime_series.name = None
+        rs = datetime_series.to_frame()
+        xp = DataFrame(datetime_series.values, index=datetime_series.index)
+        tm.assert_frame_equal(rs, xp)
+
+        datetime_series.name = "testname"
+        rs = datetime_series.to_frame()
+        xp = DataFrame(
+            dict(testname=datetime_series.values), index=datetime_series.index
+        )
+        tm.assert_frame_equal(rs, xp)
+
+        rs = datetime_series.to_frame(name="testdifferent")
+        xp = DataFrame(
+            dict(testdifferent=datetime_series.values), index=datetime_series.index
+        )
+        tm.assert_frame_equal(rs, xp)
+
+    def test_to_frame_expanddim(self):
+        # GH#9762
+
+        class SubclassedSeries(Series):
+            @property
+            def _constructor_expanddim(self):
+                return SubclassedFrame
+
+        class SubclassedFrame(DataFrame):
+            pass
+
+        ser = SubclassedSeries([1, 2, 3], name="X")
+        result = ser.to_frame()
+        assert isinstance(result, SubclassedFrame)
+        expected = SubclassedFrame({"X": [1, 2, 3]})
+        tm.assert_frame_equal(result, expected)