Added tests

.gitignore

@@ -2,6 +2,9 @@ venv/
 docs/build
 __pycache__/
 *.egg-info/
+.eggs/
 dist/
 build/
+.pytest_cache/
+.tox/
 *.pyc

README.md

@@ -69,5 +69,11 @@ To eliminate overshoot in certain types of systems, you can calculate the [propo
 pid.proportional_on_measurement = True
 ```
 
+## Tests
+Use the following to run tests:
+```
+tox
+```
+
 ## License
 Licensed under the [MIT License](https://github.com/m-lundberg/simple-pid/blob/master/LICENSE.md).

setup.py

@@ -12,7 +12,7 @@
 
 setup(
     name='simple-pid',
-    version='0.1.2',
+    version='0.1.3',
     description='A simple, easy to use PID controller',
     long_description=long_description,
     long_description_content_type='text/markdown',

tests/test_pid.py

@@ -0,0 +1,35 @@
+
+import time
+import pytest
+from simple_pid import PID
+
+
+def test_zero():
+    pid = PID(1, 1, 1, setpoint=0)
+    assert pid(0) == 0
+
+
+def test_P():
+    pid = PID(1, 0, 0, setpoint=10, sample_time=None)
+    assert pid(0) == 10
+    assert pid(5) == 5
+
+
+def test_control():
+    pid = PID(2, 1, 1, setpoint=10)
+    PV = 0
+
+    def update_system(C, dt):
+        return PV + C*dt - 1*dt
+
+    start_time = time.time()
+    last_time = start_time
+
+    while time.time() - start_time < 10:
+        C = pid(PV)
+        PV = update_system(C, time.time()-last_time)
+
+        last_time = time.time()
+
+    # check if system has converged
+    assert abs(PV - 10) < 0.1

tox.ini

@@ -0,0 +1,7 @@
+[tox]
+envlist = py27, py36, pypy
+
+[testenv]
+commands = pytest
+deps =
+    pytest