Testing Your First Python Application
In this section:
Introduction
Remember, in the first tutorial you’ve created your first Python application, and in the second tutorial you’ve debugged it. Now it’s time to do some testing.
Before you start
Open Settings/Preferences dialog (Ctrl+Alt+S), under the node click and select the default test runner - let it be unittest (refer to this page for details).
Note also that we are using unittest to test our application, but if you prefer to use another framework, PyCharm also supports nosetest and py.test.
Creating test
Open the Python file Solver.py for editing (F4). In the class Solver right-click the editor background, point to , and then choose (or just press Ctrl+Shift+T):
The pop-up appears, suggesting you to create a new test:
OK, let’s do it:
The new Python test class is created:
You see that there is the import statement, the test class, as required by the documentation, and the test method for the method demo, that just fails.
Run this test ( on the context menu) and see it failing.
However, this failing behavior is by default - let’s now provide some meaningful contents, but before that some transformation is required.
Transforming the source code
Transforming the source code of the class Solver
First, let’s transform our code a little. Let’s add a check for the zero value of d, and place all input statements out of the class Solver:
import math
class Solver:
def demo(self, a, b, c):
d = b ** 2 - 4 * a * c
if d > 0:
disc = math.sqrt(d)
root1 = (-b + disc) / (2 * a)
root2 = (-b - disc) / (2 * a)
return root1, root2
elif d == 0:
return -b / (2 * a)
else:
return "This equation has no roots"
if __name__ == '__main__':
solver = Solver()
while True:
a = int(input("a: "))
b = int(input("b: "))
c = int(input("c: "))
result = solver.demo(a, b, c)
print(result)Now you see the Run icon 
in the left gutter next to the block if __name__ == '__main__':. If you hover your mouse pointer over this icon, you will see a pop-up window describing the available commands:
Clicking this icon reveals the pop-up menu:
Choose and see your script running.
Transforming the source code of the test class
We’ll add few methods that check the equation roots, and also the method setUp:
import unittest
from Solver import Solver
class SolverTest(unittest.TestCase):
def setUp(self):
self.solver = Solver()
def test_two_roots_1(self):
self.assertEqual(self.solver.demo(2, 5, 3), (-1, -1.5))
def test_two_roots_2(self):
self.assertEqual(self.solver.demo(2, -9, 7), (3.5, 1))
def test_one_root(self):
self.assertEqual(self.solver.demo(2, 4, 2), -1)
def test_no_roots(self):
self.assertEqual(self.solver.demo(2, 1, 3), "This equation has no roots")Now run the test by right-clicking the editor background above the declaration of the class SolverTest. This time all the tests pass successfully:
