diff --git a/axe_selenium_python/axe.py b/axe_selenium_python/axe.py
index 8c74072..fe9760b 100755
--- a/axe_selenium_python/axe.py
+++ b/axe_selenium_python/axe.py
@@ -100,5 +100,8 @@ def write_results(self, data, name="results.json"):
         :param name: Name of file to be written to.
         :param output: JSON object.
         """
-        with open(name, "r", encoding="utf8") as f:
-            f.write(json.dumps(data, indent=4))
+        with open(name, "w", encoding="utf8") as f:
+            try:
+                f.write(unicode(json.dumps(data, indent=4)))
+            except NameError:
+                f.write(json.dumps(data, indent=4))
diff --git a/axe_selenium_python/tests/requirements/tests.txt b/axe_selenium_python/tests/requirements/tests.txt
index 5f06fce..dad738a 100644
--- a/axe_selenium_python/tests/requirements/tests.txt
+++ b/axe_selenium_python/tests/requirements/tests.txt
@@ -1,3 +1,4 @@
 pytest==3.8.2
 selenium==3.14.1
 pytest-html==1.19.0
+pytest-mock==1.10.0
diff --git a/axe_selenium_python/tests/test_axe.py b/axe_selenium_python/tests/test_axe.py
index 4217572..ca372e3 100755
--- a/axe_selenium_python/tests/test_axe.py
+++ b/axe_selenium_python/tests/test_axe.py
@@ -2,7 +2,8 @@
 # License, v. 2.0. If a copy of the MPL was not distributed with this file,
 # You can obtain one at http://mozilla.org/MPL/2.0/.
 
-from os import path, getenv
+import json
+from os import getenv, path
 
 import pytest
 from selenium import webdriver
@@ -62,3 +63,16 @@ def _perform_axe_run(driver):
     axe.inject()
     data = axe.execute()
     return data
+
+
+def test_write_results_to_file(tmpdir, mocker):
+    axe = Axe(mocker.MagicMock())
+    data = {"testKey": "testValue"}
+    filename = path.join(str(tmpdir), "results.json")
+
+    axe.write_results(data, filename)
+
+    with open(filename) as f:
+        actual_file_contents = json.loads(f.read())
+
+    assert data == actual_file_contents
diff --git a/tox.ini b/tox.ini
index f851245..5f669ba 100644
--- a/tox.ini
+++ b/tox.ini
@@ -3,16 +3,10 @@ envlist = py27, py36, flake8
 skipsdist = true
 
 [testenv]
-passenv = HOME DISPLAY MOZ_HEADLESS PYTEST_ADDOPTS PYTEST_BASE_URL \
-    SAUCELABS_USR SAUCELABS_PSW JENKINS_URL JOB_NAME BUILD_NUMBER
+setenv =
+  MOZ_HEADLESS = 1
 deps = -raxe_selenium_python/tests/requirements/tests.txt
-commands = pytest
-
-[testenv:py27]
-commands = pytest
-
-[testenv:py36]
-commands = pytest
+commands = pytest -rsx --verbose
 
 [testenv:flake8]
 deps = -raxe_selenium_python/tests/requirements/flake8.txt