diff --git a/test/conftest.py b/test/conftest.py
new file mode 100644
index 00000000000..afc1d5e2695
--- /dev/null
+++ b/test/conftest.py
@@ -0,0 +1,51 @@
+# This file is part of arduino-cli.
+
+# Copyright 2019 ARDUINO SA (http://www.arduino.cc/)
+
+# This software is released under the GNU General Public License version 3,
+# which covers the main part of arduino-cli.
+# The terms of this license can be found at:
+# https://www.gnu.org/licenses/gpl-3.0.en.html
+
+# You can be released from the requirements of the above licenses by purchasing
+# a commercial license. Buying such a license is mandatory if you want to modify or
+# otherwise use the software for commercial activities involving the Arduino
+# software without disclosing the source code of your own applications. To purchase
+# a commercial license, send an email to license@arduino.cc.
+import os
+
+import pytest
+from invoke import run
+
+
+@pytest.fixture(scope="session")
+def data_dir(tmpdir_factory):
+    """
+    A tmp folder will be created before running
+    the tests and deleted at the end.
+    """
+    fn = tmpdir_factory.mktemp('ArduinoTest')
+    return fn
+
+
+@pytest.fixture(scope="session")
+def run_command(data_dir):
+    """
+    Provide a wrapper around invoke's `run` API so that every test
+    will work in the same temporary folder.
+
+    Useful reference:
+        http://docs.pyinvoke.org/en/1.2/api/runners.html#invoke.runners.Result
+    """
+    cli_path = os.path.join(pytest.config.rootdir, '..', 'arduino-cli')
+    env = {
+            "ARDUINO_DATA_DIR": data_dir,
+	        "ARDUINO_DOWNLOADS_DIR": data_dir,
+	        "ARDUINO_SKETCHBOOK_DIR": data_dir
+    }
+
+    def _run(cmd_string):
+        cli_full_line = "{} {}".format(cli_path, cmd_string)
+        return run(cli_full_line, echo=False, hide=True, warn=True, env=env)
+
+    return _run
diff --git a/test/pytest.ini b/test/pytest.ini
index bde27d789f4..957be6d9fae 100644
--- a/test/pytest.ini
+++ b/test/pytest.ini
@@ -7,4 +7,5 @@ filterwarnings =
 markers =
     slow: marks tests as slow (deselect with '-m "not slow"')
 
-addopts = -s --verbose --tb=short
\ No newline at end of file
+# atm some tests depend on each other, better to exit at first failure (-x)
+addopts = -x -s --verbose --tb=short
\ No newline at end of file
diff --git a/test/test_main.py b/test/test_main.py
index 976b780deab..aa3a1cb5115 100644
--- a/test/test_main.py
+++ b/test/test_main.py
@@ -5,45 +5,26 @@
 import semver
 from datetime import datetime
 
-this_test_path = os.path.dirname(os.path.realpath(__file__))
-# Calculate absolute path of the CLI
-cli_path = os.path.join(this_test_path, '..', 'arduino-cli')
 
-# Useful reference: 
-# http://docs.pyinvoke.org/en/1.2/api/runners.html#invoke.runners.Result
-
-
-def cli_line(*args):
-    # Accept a list of arguments cli_line('lib list --format json')
-    # Return a full command line string e.g. 'arduino-cli help --format json'
-    cli_full_line = ' '.join([cli_path, ' '.join(str(arg) for arg in args)])
-    return cli_full_line
-
-
-def run_command(*args):
-    result = run(cli_line(*args), echo=False, hide=True, warn=True)
-    return result
-
-
-def test_command_help():
+def test_command_help(run_command):
     result = run_command('help')
     assert result.ok
     assert result.stderr == ''
     assert 'Usage' in result.stdout
 
 
-def test_command_lib_list():
+def test_command_lib_list(run_command):
     """
     When ouput is empty, nothing is printed out, no matter the output format
     """
     result = run_command('lib list')
     assert result.ok
     assert '' == result.stderr
-    result = run_command('lib list', '--format json')
+    result = run_command('lib list --format json')
     assert '' == result.stdout
 
 
-def test_command_lib_install():
+def test_command_lib_install(run_command):
     libs = ['\"AzureIoTProtocol_MQTT\"', '\"CMMC MQTT Connector\"', '\"WiFiNINA\"']
     # Should be safe to run install multiple times
     result_1 = run_command('lib install {}'.format(' '.join(libs)))
@@ -51,18 +32,18 @@ def test_command_lib_install():
     result_2 = run_command('lib install {}'.format(' '.join(libs)))
     assert result_2.ok
 
-def test_command_lib_update_index():
+def test_command_lib_update_index(run_command):
     result = run_command('lib update-index')
     assert result.ok
     assert 'Updating index: library_index.json downloaded' == result.stdout.splitlines()[-1].strip()
 
-def test_command_lib_remove():
+def test_command_lib_remove(run_command):
     libs = ['\"AzureIoTProtocol_MQTT\"', '\"CMMC MQTT Connector\"', '\"WiFiNINA\"']
     result = run_command('lib uninstall {}'.format(' '.join(libs)))
     assert result.ok
 
 @pytest.mark.slow
-def test_command_lib_search():
+def test_command_lib_search(run_command):
     result = run_command('lib search')
     assert result.ok
     out_lines = result.stdout.splitlines()
@@ -81,7 +62,7 @@ def test_command_lib_search():
     assert number_of_libs == number_of_libs_from_json
 
 
-def test_command_board_list():
+def test_command_board_list(run_command):
     result = run_command('board list --format json')
     assert result.ok
     # check is a valid json and contains a list of ports
@@ -92,13 +73,13 @@ def test_command_board_list():
         assert 'protocol_label' in port
 
 
-def test_command_board_listall():
+def test_command_board_listall(run_command):
     result = run_command('board listall')
     assert result.ok
     assert ['Board', 'Name', 'FQBN'] == result.stdout.splitlines()[0].strip().split()
 
 
-def test_command_version():
+def test_command_version(run_command):
     result = run_command('version --format json')
     assert result.ok
     parsed_out = json.loads(result.stdout)