diff --git a/.gitignore b/.gitignore
index c00201e..e993a91 100644
--- a/.gitignore
+++ b/.gitignore
@@ -54,3 +54,6 @@ docs/_build/
 
 # PyBuilder
 target/
+
+# PyCharm
+.idea/
diff --git a/README.rst b/README.rst
index c8a2967..0da0716 100644
--- a/README.rst
+++ b/README.rst
@@ -109,3 +109,10 @@ Some helper functions:
     pms.hex2bin(msg)        # convert hexadecimal string to binary string
     pms.hex2int(msg)        # convert hexadecimal string to integer
     pms.bin2int(msg)        # convert binary string to integer
+
+Developement
+------------
+To run tests, run the following commands:
+```
+$ tox
+```
diff --git a/pyModeS/__init__.py b/pyModeS/__init__.py
index 5be7b05..e69de29 100644
--- a/pyModeS/__init__.py
+++ b/pyModeS/__init__.py
@@ -1,5 +0,0 @@
-from __future__ import absolute_import, print_function, division
-
-from .util import *
-from . import adsb
-from . import ehs
diff --git a/pyModeS/adsb.py b/pyModeS/adsb.py
index b530f91..85cfa89 100644
--- a/pyModeS/adsb.py
+++ b/pyModeS/adsb.py
@@ -18,8 +18,7 @@ A python package for decoding ABS-D messages.
 """
 
 import math
-from . import util
-from .util import crc
+from pyModeS import util
 
 
 def df(msg):
diff --git a/pyModeS/ehs.py b/pyModeS/ehs.py
index 9a7a9df..b1446e8 100644
--- a/pyModeS/ehs.py
+++ b/pyModeS/ehs.py
@@ -17,8 +17,8 @@
 A python package for decoding ModeS (DF20, DF21) messages.
 """
 
-from . import util
-from .util import crc
+from pyModeS import util
+from pyModeS.util import crc
 
 
 def df(msg):
diff --git a/tests/adsb_test.py b/tests/adsb_test.py
new file mode 100644
index 0000000..75bc6cc
--- /dev/null
+++ b/tests/adsb_test.py
@@ -0,0 +1,63 @@
+from pyModeS import adsb
+
+
+# === TEST ADS-B package ===
+
+def test_adsb_icao():
+    assert adsb.icao("8D406B902015A678D4D220AA4BDA") == "406B90"
+
+
+def test_adsb_category():
+    assert adsb.category("8D406B902015A678D4D220AA4BDA") == 5
+
+
+def test_adsb_callsign():
+    assert adsb.callsign("8D406B902015A678D4D220AA4BDA") == "EZY85MH_"
+
+
+def test_adsb_position():
+    pos = adsb.position("8D40058B58C901375147EFD09357",
+                        "8D40058B58C904A87F402D3B8C59",
+                        1446332400, 1446332405)
+    assert pos == (49.81755, 6.08442)
+
+
+def test_adsb_airborne_position_with_ref():
+    pos = adsb.airborne_position_with_ref("8D40058B58C901375147EFD09357",
+                                          49.0, 6.0)
+    assert pos == (49.82410, 6.06785)
+    pos = adsb.airborne_position_with_ref("8D40058B58C904A87F402D3B8C59",
+                                          49.0, 6.0)
+    assert pos == (49.81755, 6.08442)
+
+
+def test_adsb_surface_position_with_ref():
+    pos = adsb.surface_position_with_ref("8FC8200A3AB8F5F893096B22B4A8",
+                                         -43.5, 172.5)
+    assert pos == (-43.48564, 175.87195)
+
+
+def test_adsb_alt():
+    assert adsb.altitude("8D40058B58C901375147EFD09357") == 39000
+
+
+def test_adsb_velocity():
+    vgs = adsb.velocity("8D485020994409940838175B284F")
+    vas = adsb.velocity("8DA05F219B06B6AF189400CBC33F")
+    assert vgs == (159, 182.9, -14, 'GS')
+    assert vas == (376, 244.0, -37, 'AS')
+
+
+def test_nic():
+    assert adsb.nic('8D3C70A390AB11F55B8C57F65FE6') == 0
+    assert adsb.nic('8DE1C9738A4A430B427D219C8225') == 1
+    assert adsb.nic('8D44058880B50006B1773DC2A7E9') == 2
+    assert adsb.nic('8D44058881B50006B1773DC2A7E9') == 3
+    assert adsb.nic('8D4AB42A78000640000000FA0D0A') == 4
+    assert adsb.nic('8D4405887099F5D9772F37F86CB6') == 5
+    assert adsb.nic('8D4841A86841528E72D9B472DAC2') == 6
+    assert adsb.nic('8D44057560B9760C0B840A51C89F') == 7
+    assert adsb.nic('8D40621D58C382D690C8AC2863A7') == 8
+    assert adsb.nic('8F48511C598D04F12CCF82451642') == 9
+    assert adsb.nic('8DA4D53A50DBF8C6330F3B35458F') == 10
+    assert adsb.nic('8D3C4ACF4859F1736F8E8ADF4D67') == 11
diff --git a/tests/decode_test_data.py b/tests/decode_test_data.py
new file mode 100644
index 0000000..c925d4d
--- /dev/null
+++ b/tests/decode_test_data.py
@@ -0,0 +1,75 @@
+# If you get import error run with ipython
+from pyModeS import adsb
+from pyModeS import ehs
+
+
+# === Decode sample data file ===
+
+def adsb_decode_all(n=None):
+    print "===== Decode all ADS-B sample data====="
+    import csv
+    f = open('tests/adsb.csv', 'rt')
+
+    msg0 = None
+    msg1 = None
+
+    for i, r in enumerate(csv.reader(f)):
+        if n and i > n:
+            break
+
+        ts = r[0]
+        m = r[1]
+        icao = adsb.icao(m)
+        tc = adsb.typecode(m)
+        if 1 <= tc <= 4:
+            print ts, m, icao, tc, adsb.category(m), adsb.callsign(m)
+        if tc == 19:
+            print ts, m, icao, tc, adsb.velocity(m)
+        if 5 <= tc <= 18:
+            if adsb.oe_flag(m):
+                msg1 = m
+                t1 = ts
+            else:
+                msg0 = m
+                t0 = ts
+
+            if msg0 and msg1:
+                pos = adsb.position(msg0, msg1, t0, t1)
+                alt = adsb.altitude(m)
+                print ts, m, icao, tc, pos, alt
+
+
+def ehs_decode_all(n=None):
+    print "===== Decode all Mode-S EHS sample data====="
+    import csv
+    f = open('tests/ehs.csv', 'rt')
+    for i, r in enumerate(csv.reader(f)):
+        if n and i > n:
+            break
+
+        ts = r[1]
+        m = r[2]
+        icao = ehs.icao(m)
+        vBDS = ehs.BDS(m)
+
+        if vBDS:
+            if vBDS == "BDS20":
+                print ts, m, icao, vBDS, ehs.callsign(m)
+
+            if vBDS == "BDS40":
+                print ts, m, icao, vBDS, ehs.alt_mcp(m), \
+                      ehs.alt_fms(m), ehs.pbaro(m)
+
+            if vBDS == "BDS50":
+                print ts, m, icao, vBDS, ehs.roll(m), ehs.track(m), \
+                      ehs.gs(m), ehs.rtrack(m), ehs.tas(m)
+
+            if vBDS == "BDS60":
+                print ts, m, icao, vBDS, ehs.heading(m), ehs.ias(m), \
+                      ehs.mach(m), ehs.baro_vr(m), ehs.ins_vr(m)
+        else:
+            print ts, m, icao, vBDS
+
+if __name__ == '__main__':
+    adsb_decode_all(100)
+    ehs_decode_all(100)
diff --git a/tests/ehs_test.py b/tests/ehs_test.py
new file mode 100644
index 0000000..9b6fbcc
--- /dev/null
+++ b/tests/ehs_test.py
@@ -0,0 +1,42 @@
+from pyModeS import ehs
+
+
+def test_ehs_icao():
+    assert ehs.icao("A0001839CA3800315800007448D9") == '400940'
+    assert ehs.icao("A000139381951536E024D4CCF6B5") == '3C4DD2'
+    assert ehs.icao("A000029CFFBAA11E2004727281F1") == '4243D0'
+
+
+def test_ehs_BDS():
+    assert ehs.BDS("A0001838201584F23468207CDFA5") == 'BDS20'
+    assert ehs.BDS("A0001839CA3800315800007448D9") == 'BDS40'
+    assert ehs.BDS("A000139381951536E024D4CCF6B5") == 'BDS50'
+    assert ehs.BDS("A000029CFFBAA11E2004727281F1") == 'BDS60'
+    assert ehs.BDS("A0281838CAE9E12FA03FFF2DDDE5") is None
+
+
+def test_ehs_BDS20_callsign():
+    assert ehs.callsign("A000083E202CC371C31DE0AA1CCF") == 'KLM1017_'
+    assert ehs.callsign("A0001993202422F2E37CE038738E") == 'IBK2873_'
+
+
+def test_ehs_BDS40_functions():
+    assert ehs.alt_mcp("A000029C85E42F313000007047D3") == 3008
+    assert ehs.alt_fms("A000029C85E42F313000007047D3") == 3008
+    assert ehs.pbaro("A000029C85E42F313000007047D3") == 1020.0
+
+
+def test_ehs_BDS50_functions():
+    assert ehs.roll("A000139381951536E024D4CCF6B5") == 2.1
+    assert ehs.track("A000139381951536E024D4CCF6B5") == 114.3
+    assert ehs.gs("A000139381951536E024D4CCF6B5") == 438
+    assert ehs.rtrack("A000139381951536E024D4CCF6B5") == 0.125
+    assert ehs.tas("A000139381951536E024D4CCF6B5") == 424
+
+
+def test_ehs_BDS60_functions():
+    assert ehs.heading("A000029CFFBAA11E2004727281F1") == 180.9
+    assert ehs.ias("A000029CFFBAA11E2004727281F1") == 336
+    assert ehs.mach("A000029CFFBAA11E2004727281F1") == 0.48
+    assert ehs.baro_vr("A000029CFFBAA11E2004727281F1") == 0
+    assert ehs.ins_vr("A000029CFFBAA11E2004727281F1") == -3648
\ No newline at end of file
diff --git a/tests/run.py b/tests/run.py
deleted file mode 100644
index 5d9cbe3..0000000
--- a/tests/run.py
+++ /dev/null
@@ -1,202 +0,0 @@
-import os, sys, inspect
-currentdir = os.path.dirname(os.path.abspath(
-                inspect.getfile(inspect.currentframe())))
-parentdir = os.path.dirname(currentdir)
-sys.path.insert(0, parentdir)
-
-import pyModeS as pms
-from pyModeS import adsb
-from pyModeS import ehs
-from pyModeS import util
-
-
-# === TEST common functions ===
-def test_hex2bin():
-    assert util.hex2bin('6E406B') == "011011100100000001101011"
-
-
-def test_crc():
-    # crc decoder
-    checksum = util.crc("8D406B902015A678D4D220AA4BDA")
-    assert checksum == "000000000000000000000000"
-
-    # crc encoder
-    parity = util.crc("8D406B902015A678D4D220AA4BDA", encode=True)
-    assert util.hex2bin("AA4BDA") == parity
-
-
-# === TEST ADS-B package ===
-
-def test_adsb_icao():
-    assert adsb.icao("8D406B902015A678D4D220AA4BDA") == "406B90"
-
-
-def test_adsb_category():
-    assert adsb.category("8D406B902015A678D4D220AA4BDA") == 5
-
-
-def test_adsb_callsign():
-    assert adsb.callsign("8D406B902015A678D4D220AA4BDA") == "EZY85MH_"
-
-
-def test_adsb_airborne_position():
-    pos = adsb.airborne_position("8D40058B58C901375147EFD09357",
-                                 "8D40058B58C904A87F402D3B8C59",
-                                 1446332400, 1446332405)
-    assert pos == (49.81755, 6.08442)
-
-
-def test_adsb_airborne_position_with_ref():
-    pos = adsb.airborne_position_with_ref("8D40058B58C901375147EFD09357",
-                                          49.0, 6.0)
-    assert pos == (49.82410, 6.06785)
-    pos = adsb.airborne_position_with_ref("8D40058B58C904A87F402D3B8C59",
-                                          49.0, 6.0)
-    assert pos == (49.81755, 6.08442)
-
-
-def test_adsb_surface_position_with_ref():
-    pos = adsb.surface_position_with_ref("8FC8200A3AB8F5F893096B22B4A8",
-                                         -43.5, 172.5)
-    assert pos == (-43.48564, 175.87195)
-
-
-def test_adsb_alt():
-    assert adsb.altitude("8D40058B58C901375147EFD09357") == 39000
-
-
-def test_adsb_velocity():
-    vgs = adsb.velocity("8D485020994409940838175B284F")
-    vas = adsb.velocity("8DA05F219B06B6AF189400CBC33F")
-    assert vgs == (159, 182.9, -14, 'GS')
-    assert vas == (376, 244.0, -37, 'AS')
-
-
-def test_nic():
-    assert adsb.nic('8D3C70A390AB11F55B8C57F65FE6') == 0
-    assert adsb.nic('8DE1C9738A4A430B427D219C8225') == 1
-    assert adsb.nic('8D44058880B50006B1773DC2A7E9') == 2
-    assert adsb.nic('8D44058881B50006B1773DC2A7E9') == 3
-    assert adsb.nic('8D4AB42A78000640000000FA0D0A') == 4
-    assert adsb.nic('8D4405887099F5D9772F37F86CB6') == 5
-    assert adsb.nic('8D4841A86841528E72D9B472DAC2') == 6
-    assert adsb.nic('8D44057560B9760C0B840A51C89F') == 7
-    assert adsb.nic('8D40621D58C382D690C8AC2863A7') == 8
-    assert adsb.nic('8F48511C598D04F12CCF82451642') == 9
-    assert adsb.nic('8DA4D53A50DBF8C6330F3B35458F') == 10
-    assert adsb.nic('8D3C4ACF4859F1736F8E8ADF4D67') == 11
-
-
-# === TEST Mode-S EHS package ===
-
-def test_ehs_icao():
-    assert ehs.icao("A0001839CA3800315800007448D9") == '400940'
-    assert ehs.icao("A000139381951536E024D4CCF6B5") == '3C4DD2'
-    assert ehs.icao("A000029CFFBAA11E2004727281F1") == '4243D0'
-
-
-def test_ehs_BDS():
-    assert ehs.BDS("A0001838201584F23468207CDFA5") == 'BDS20'
-    assert ehs.BDS("A0001839CA3800315800007448D9") == 'BDS40'
-    assert ehs.BDS("A000139381951536E024D4CCF6B5") == 'BDS50'
-    assert ehs.BDS("A000029CFFBAA11E2004727281F1") == 'BDS60'
-    assert ehs.BDS("A0281838CAE9E12FA03FFF2DDDE5") is None
-
-
-def test_ehs_BDS20_callsign():
-    assert ehs.callsign("A000083E202CC371C31DE0AA1CCF") == 'KLM1017_'
-    assert ehs.callsign("A0001993202422F2E37CE038738E") == 'IBK2873_'
-
-
-def test_ehs_BDS40_functions():
-    assert ehs.alt_mcp("A000029C85E42F313000007047D3") == 3008
-    assert ehs.alt_fms("A000029C85E42F313000007047D3") == 3008
-    assert ehs.pbaro("A000029C85E42F313000007047D3") == 1020.0
-
-
-def test_ehs_BDS50_functions():
-    assert ehs.roll("A000139381951536E024D4CCF6B5") == 2.1
-    assert ehs.track("A000139381951536E024D4CCF6B5") == 114.3
-    assert ehs.gs("A000139381951536E024D4CCF6B5") == 438
-    assert ehs.rtrack("A000139381951536E024D4CCF6B5") == 0.125
-    assert ehs.tas("A000139381951536E024D4CCF6B5") == 424
-
-
-def test_ehs_BDS60_functions():
-    assert ehs.heading("A000029CFFBAA11E2004727281F1") == 180.9
-    assert ehs.ias("A000029CFFBAA11E2004727281F1") == 336
-    assert ehs.mach("A000029CFFBAA11E2004727281F1") == 0.48
-    assert ehs.baro_vr("A000029CFFBAA11E2004727281F1") == 0
-    assert ehs.ins_vr("A000029CFFBAA11E2004727281F1") == -3648
-
-
-# === Decode sample data file ===
-
-def adsb_decode_all(n=None):
-    print("===== Decode all ADS-B sample data=====")
-    import csv
-    f = open('adsb.csv', 'rt')
-
-    msg0 = None
-    msg1 = None
-
-    for i, r in enumerate(csv.reader(f)):
-        if n and i > n:
-            break
-
-        ts = r[0]
-        m = r[1]
-        icao = adsb.icao(m)
-        tc = adsb.typecode(m)
-        if 1 <= tc <= 4:
-            print(ts, m, icao, tc, adsb.category(m), adsb.callsign(m))
-        if tc == 19:
-            print(ts, m, icao, tc, adsb.velocity(m))
-        if 5 <= tc <= 18:
-            if adsb.oe_flag(m):
-                msg1 = m
-                t1 = ts
-            else:
-                msg0 = m
-                t0 = ts
-
-            if msg0 and msg1:
-                pos = adsb.position(msg0, msg1, t0, t1)
-                alt = adsb.altitude(m)
-                print(ts, m, icao, tc, pos, alt)
-
-
-def ehs_decode_all(n=None):
-    print("===== Decode all Mode-S EHS sample data=====")
-    import csv
-    f = open('ehs.csv', 'rt')
-    for i, r in enumerate(csv.reader(f)):
-        if n and i > n:
-            break
-
-        ts = r[1]
-        m = r[2]
-        icao = ehs.icao(m)
-        vBDS = ehs.BDS(m)
-
-        if vBDS:
-            if vBDS == "BDS20":
-                print(ts, m, icao, vBDS, ehs.callsign(m))
-
-            if vBDS == "BDS40":
-                print(ts, m, icao, vBDS, ehs.alt_mcp(m), \
-                      ehs.alt_fms(m), ehs.pbaro(m))
-
-            if vBDS == "BDS50":
-                print(ts, m, icao, vBDS, ehs.roll(m), ehs.track(m), \
-                      ehs.gs(m), ehs.rtrack(m), ehs.tas(m))
-
-            if vBDS == "BDS60":
-                print(ts, m, icao, vBDS, ehs.heading(m), ehs.ias(m), \
-                      ehs.mach(m), ehs.baro_vr(m), ehs.ins_vr(m))
-        else:
-            print(ts, m, icao, vBDS)
-
-if __name__ == '__main__':
-    adsb_decode_all(100)
-    ehs_decode_all(100)
diff --git a/tests/util_test.py b/tests/util_test.py
new file mode 100644
index 0000000..758bf4e
--- /dev/null
+++ b/tests/util_test.py
@@ -0,0 +1,15 @@
+from pyModeS import util
+
+
+def test_hex2bin():
+    assert util.hex2bin('6E406B') == "011011100100000001101011"
+
+
+def test_crc_decode():
+    checksum = util.crc("8D406B902015A678D4D220AA4BDA")
+    assert checksum == "000000000000000000000000"
+
+
+def test_crc_encode():
+    parity = util.crc("8D406B902015A678D4D220AA4BDA", encode=True)
+    assert util.hex2bin("AA4BDA") == parity
\ No newline at end of file
diff --git a/tox.ini b/tox.ini
new file mode 100644
index 0000000..8afc68f
--- /dev/null
+++ b/tox.ini
@@ -0,0 +1,5 @@
+[tox]
+envlist = py26,py27,py35
+[testenv]
+deps=pytest
+commands=py.test