diff --git a/.travis.yml b/.travis.yml
index 90f98bc9..c0dcea04 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -44,13 +44,13 @@ install:
   # FIXME: Mamba causes pip install numpy to be extremely slow
   - if [[ "${PYVER}" = pypy* ]]; then
       conda create --quiet --yes -n testenv ${PYVER};
-    elif [ "${PYVER}" = "2.7" ] || [ "${PYVER}" = "3.6" ] || [ "${PYVER}" = "3.7" ]; then
+    elif [ "${PYVER}" = "2.7" ] || [ "${PYVER}" = "3.6" ] || [ "${PYVER}" = "3.7" || [ "${PYVER}" = "3.8" ]; then
       conda create --quiet --yes -n testenv python=${PYVER} pip;
     else
       conda create --quiet --yes -n testenv python=${PYVER};
     fi
   - source activate testenv
-  - if [ "${PYVER}" = "2.7" ] || [ "${PYVER}" = "3.6" ] || [ "${PYVER}" = "3.7" ]; then
+  - if [ "${PYVER}" = "2.7" ] || [ "${PYVER}" = "3.6" ] || [ "${PYVER}" = "3.7" || [ "${PYVER}" = "3.8" ]; then
       conda install --quiet --yes python=${PYVER} pip root;
       source activate testenv;
     fi
@@ -69,6 +69,7 @@ install:
       conda install -c anaconda python=${PYVER} pyopenssl;
     fi
   - wget -O tests/samples/Event.root http://scikit-hep.org/uproot/examples/Event.root
+  - pip install git+https://github.com/chrisburr/pytest-error-for-skips.git@patch-1
 
 addons:
   apt:
@@ -77,7 +78,11 @@ addons:
       - libatlas-base-dev
 
 script:
-  pytest -v tests
+  if [ "${PYVER}" = "2.7" ] || [ "${PYVER}" = "3.6" ] || [ "${PYVER}" = "3.7" || [ "${PYVER}" = "3.8" ]; then
+    pytest --error-for-skips -v tests;
+  else
+    pytest -v tests;
+  fi
 
 notifications:
   slack: scikit-hep:b6cgBXwccPoaCNLn5VKFJFVy
diff --git a/tests/test_cache.py b/tests/test_cache.py
index 17809d3d..5752ca81 100644
--- a/tests/test_cache.py
+++ b/tests/test_cache.py
@@ -2,13 +2,9 @@
 
 # BSD 3-Clause License; see https://github.com/scikit-hep/uproot/blob/master/LICENSE
 
-import unittest
-
-from collections import namedtuple
-
 import uproot
 
-class Test(unittest.TestCase):
+class Test(object):
     def test_flat_array(self):
         branch = uproot.open("tests/samples/sample-6.10.05-uncompressed.root")["sample"]["i8"]
         expectation = [-15, -14, -13, -12, -11, -10, -9, -8, -7, -6, -5, -4, -3, -2, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14]
diff --git a/tests/test_compression.py b/tests/test_compression.py
index da755139..fbf1e928 100644
--- a/tests/test_compression.py
+++ b/tests/test_compression.py
@@ -2,8 +2,6 @@
 
 # BSD 3-Clause License; see https://github.com/scikit-hep/uproot/blob/master/LICENSE
 
-import unittest
-
 try:
     import lzma
 except ImportError:
@@ -13,7 +11,7 @@
 
 import uproot
 
-class Test(unittest.TestCase):
+class Test(object):
     def test_compression_identity(self):
         assert uproot.open("tests/samples/Zmumu-zlib.root").compression.algoname == "zlib"
         assert uproot.open("tests/samples/Zmumu-zlib.root").compression.level == 4
diff --git a/tests/test_http.py b/tests/test_http.py
index 251b74e5..e52dd02a 100644
--- a/tests/test_http.py
+++ b/tests/test_http.py
@@ -2,8 +2,6 @@
 
 # BSD 3-Clause License; see https://github.com/scikit-hep/uproot/blob/master/LICENSE
 
-import unittest
-
 import pytest
 import mock
 from requests.exceptions import HTTPError
@@ -41,7 +39,7 @@ def raise_for_status(self):
         return MockResponse(401)
 
 @mock.patch("requests.get", mock_get_local_instead_of_http)
-class Test(unittest.TestCase):
+class Test(object):
     def test_no_auth_needed_no_auth(self):
         f = uproot.open(URL)
         assert type(f) == uproot.rootio.ROOTDirectory
diff --git a/tests/test_issues.py b/tests/test_issues.py
index 28960335..44adc0cf 100644
--- a/tests/test_issues.py
+++ b/tests/test_issues.py
@@ -2,10 +2,6 @@
 
 # BSD 3-Clause License; see https://github.com/scikit-hep/uproot/blob/master/LICENSE
 
-import unittest
-
-from collections import namedtuple
-
 import pytest
 import numpy
 
@@ -16,7 +12,7 @@
 import uproot_methods.classes.TLorentzVector
 
 
-class Test(unittest.TestCase):
+class Test(object):
     def test_issue21(self):
         t = uproot.open("tests/samples/issue21.root")["nllscan"]
 
@@ -271,27 +267,18 @@ def test_issue213(self):
         ]
 
     def test_issue232(self):
-        try:
-            import pandas
-        except ImportError:
-            pass
-        else:
-            t = uproot.open("tests/samples/issue232.root")["fTreeV0"]
-            t.pandas.df(
-                ["V0Hyper.fNsigmaHe3Pos", "V0Hyper.fDcaPos2PrimaryVertex"],
-                flatten=True)
-
-    @pytest.mark.skip(reason="This one takes way too long (eospublic?).")
+        pytest.importorskip("pandas")
+        t = uproot.open("tests/samples/issue232.root")["fTreeV0"]
+        t.pandas.df(
+            ["V0Hyper.fNsigmaHe3Pos", "V0Hyper.fDcaPos2PrimaryVertex"],
+            flatten=True)
+
     def test_issue240(self):
-        try:
-            import pyxrootd
-        except ImportError:
-            pytest.skip("unable to import pyxrootd")
-        else:
-            t = uproot.open(
-                "root://eospublic.cern.ch//eos/root-eos/cms_opendata_2012_nanoaod/Run2012B_DoubleMuParked.root"
-            )["Events"]
-            assert (abs(t.array("nMuon")) < 50).all()
+        pytest.importorskip("pyxrootd")
+        t = uproot.open(
+            "root://eospublic.cern.ch//eos/root-eos/cms_opendata_2012_nanoaod/Run2012B_DoubleMuParked.root"
+        )["Events"]
+        assert (abs(t.array("nMuon", entrystop=100000)) < 50).all()
 
     def test_issue243(self):
         t = uproot.open("tests/samples/issue243.root")["triggerList"]
diff --git a/tests/test_jagged.py b/tests/test_jagged.py
index 5cfe8899..9019fea0 100644
--- a/tests/test_jagged.py
+++ b/tests/test_jagged.py
@@ -2,35 +2,35 @@
 
 # BSD 3-Clause License; see https://github.com/scikit-hep/uproot/blob/master/LICENSE
 
-import unittest
+import pytest
 
 import uproot
-try:
-    import pandas
-except ImportError:
-    pandas = None
 
-class Test(unittest.TestCase):
-    if pandas is not None:
-        sample = uproot.open("tests/samples/sample-6.10.05-uncompressed.root")["sample"]
+
+class Test(object):
+    @property
+    def sample(self):
+        pytest.importorskip("pandas")
+        try:
+            self._sample
+        except AttributeError:
+            self._sample = uproot.open("tests/samples/sample-6.10.05-uncompressed.root")["sample"]
+        return self._sample
 
     def test_flatten_False(self):
-        if pandas is not None:
-            df = self.sample.pandas.df(flatten=False)
-            assert len(df.keys()) == 57
-            assert "Af8" in df
-            assert len(df.at[0, "Af8"]) == 0
-            assert len(df.at[1, "Af8"]) == 1
-            assert len(df.at[2, "Af8"]) == 2
+        df = self.sample.pandas.df(flatten=False)
+        assert len(df.keys()) == 57
+        assert "Af8" in df
+        assert len(df.at[0, "Af8"]) == 0
+        assert len(df.at[1, "Af8"]) == 1
+        assert len(df.at[2, "Af8"]) == 2
 
     def test_flatten_None(self):
-        if pandas is not None:
-            df = self.sample.pandas.df(flatten=None)
-            assert len(df.keys()) == 46
-            assert "Af8" not in df
+        df = self.sample.pandas.df(flatten=None)
+        assert len(df.keys()) == 46
+        assert "Af8" not in df
 
     def test_flatten_True(self):
-        if pandas is not None:
-            df = self.sample.pandas.df(flatten=True)
-            assert len(df.keys()) == 57
-            assert "Af8" in df
+        df = self.sample.pandas.df(flatten=True)
+        assert len(df.keys()) == 57
+        assert "Af8" in df
diff --git a/tests/test_stlvector.py b/tests/test_stlvector.py
index aa1c9ab3..03733e12 100644
--- a/tests/test_stlvector.py
+++ b/tests/test_stlvector.py
@@ -2,13 +2,9 @@
 
 # BSD 3-Clause License; see https://github.com/scikit-hep/uproot/blob/master/LICENSE
 
-import unittest
-
-from collections import namedtuple
-
 import uproot
 
-class Test(unittest.TestCase):
+class Test(object):
     def runTest(self):
         pass
 
diff --git a/tests/test_tree.py b/tests/test_tree.py
index ecb4d3e0..cf4fdfcf 100644
--- a/tests/test_tree.py
+++ b/tests/test_tree.py
@@ -3,8 +3,6 @@
 # BSD 3-Clause License; see https://github.com/scikit-hep/uproot/blob/master/LICENSE
 
 import os
-import unittest
-
 from collections import namedtuple
 
 import numpy
@@ -18,7 +16,7 @@ def basest(array):
         array = array.base
     return array
 
-class Test(unittest.TestCase):
+class Test(object):
     ###################################################### double32
 
     def test_double32(self):
@@ -594,9 +592,12 @@ def test_tree_lazy_cached(self):
             for i in range(len(lazy), 0, -1):
                 assert lazy[i - 1 : i + 3].tolist() == strict[i - 1 : i + 3].tolist()
 
-    def test_hist_in_tree(self):
-        path = os.path.join("tests", "samples", "Event.root")
-        if os.path.exists(path):
+    @pytest.mark.parametrize("use_http", [False, True])
+    def test_hist_in_tree(self, use_http):
+        if use_http:
+            path = os.path.join("tests", "samples", "Event.root")
+            if not os.path.exists(path):
+                raise pytest.skip()
             tree = uproot.open(path)["T"]
         else:
             tree = uproot.open("http://scikit-hep.org/uproot/examples/Event.root")["T"]
@@ -610,7 +611,8 @@ def test_hist_in_tree(self):
 
         assert tree.array("fH")[20].values.tolist() == check
 
-    def test_branch_auto_interpretation(self):
+    @pytest.mark.parametrize("use_http", [False, True])
+    def test_branch_auto_interpretation(self, use_http):
         # The aim is to reduce this list in a controlled manner
         known_branches_without_interp = [
             b'event',
@@ -622,8 +624,10 @@ def test_branch_auto_interpretation(self):
             b'fTriggerBits',
             b'fTriggerBits.TObject'
         ]
-        path = os.path.join("tests", "samples", "Event.root")
-        if os.path.exists(path):
+        if use_http:
+            path = os.path.join("tests", "samples", "Event.root")
+            if not os.path.exists(path):
+                raise pytest.skip()
             tree = uproot.open(path)["T"]
         else:
             tree = uproot.open("http://scikit-hep.org/uproot/examples/Event.root")["T"]
@@ -650,24 +654,20 @@ def test_leaflist(self):
         assert a["y"].tolist() == [1, 2, 3, 4, 5]
         assert a["z"].tolist() == [ord("a"), ord("b"), ord("c"), ord("d"), ord("e")]
 
-        try:
-            import pandas
-        except ImportError:
-            pass
-        else:
-            assert tree.pandas.df()["leaflist.x"].tolist() == [1.1, 2.2, 3.3, 4.0, 5.5]
-
-            tree = uproot.open("tests/samples/HZZ-objects.root")["events"]
-            tree.pandas.df("muonp4")
-            tree.pandas.df("muonp4", flatten=False)
-            df = tree.pandas.df("eventweight", entrystart=100, entrystop=200)
-            index = df.index.tolist()
-            assert min(index) == 100
-            assert max(index) == 199
-            df = tree.pandas.df("muonp4", entrystart=100, entrystop=200)
-            index = df.index.get_level_values("entry").tolist()
-            assert min(index) == 100
-            assert max(index) == 199
+        pytest.importorskip("pandas")
+        assert tree.pandas.df()["leaflist.x"].tolist() == [1.1, 2.2, 3.3, 4.0, 5.5]
+
+        tree = uproot.open("tests/samples/HZZ-objects.root")["events"]
+        tree.pandas.df("muonp4")
+        tree.pandas.df("muonp4", flatten=False)
+        df = tree.pandas.df("eventweight", entrystart=100, entrystop=200)
+        index = df.index.tolist()
+        assert min(index) == 100
+        assert max(index) == 199
+        df = tree.pandas.df("muonp4", entrystart=100, entrystop=200)
+        index = df.index.get_level_values("entry").tolist()
+        assert min(index) == 100
+        assert max(index) == 199
 
     def test_mempartitions(self):
         t = uproot.open("tests/samples/sample-5.23.02-zlib.root")["sample"]
diff --git a/tests/test_versions.py b/tests/test_versions.py
index ceeff735..e31526f1 100644
--- a/tests/test_versions.py
+++ b/tests/test_versions.py
@@ -2,8 +2,6 @@
 
 # BSD 3-Clause License; see https://github.com/scikit-hep/uproot/blob/master/LICENSE
 
-import unittest
-
 try:
     import lzma
 except ImportError:
@@ -12,7 +10,7 @@
 
 import uproot
 
-class Test(unittest.TestCase):
+class Test(object):
     sample = {
         b"n": [0, 1, 2, 3, 4, 0, 1, 2, 3, 4, 0, 1, 2, 3, 4, 0, 1, 2, 3, 4, 0, 1, 2, 3, 4, 0, 1, 2, 3, 4],
 
diff --git a/uproot/source/http.py b/uproot/source/http.py
index 1011359c..d9df3eff 100644
--- a/uproot/source/http.py
+++ b/uproot/source/http.py
@@ -40,7 +40,7 @@ def _read(self, chunkindex):
         while True:
             response = requests.get(
                 self.path,
-                headers={"Range": "bytes={0}-{1}".format(chunkindex * self._chunkbytes, (chunkindex + 1) * self._chunkbytes)},
+                headers={"Range": "bytes={0}-{1}".format(chunkindex * self._chunkbytes, (chunkindex + 1) * self._chunkbytes - 1)},
                 auth=self.auth,
             )
             if response.status_code == 504:   # timeout, try it again