Classes

If you haven’t installed gridtest, you should do this first.

Write Functions

Let’s say we start with these functions, and save them to a file called car.py

# Example car class to run tests for

valid_colors = ["red", "black", "white", "blue"]

# An example of raising a custom exception
class ColorException(Exception):
    pass

class WheelsException(Exception):
    pass


class Car:

    def __init__(self, wheels:int=4, color:str="red", lights:bool=False):
        """a new car must have an even number of wheels, and be a valid color
        """
        if color not in valid_colors:
            raise ColorException
        if wheels % 2 != 0:
            raise WheelsException
        self.wheels = wheels
        self.color = color
        self.lights = lights

    def __str__(self):
        return (f"[car][wheels:{self.wheels}][color:{self.color}]")
    def __repr__(self):
        return self.__str__()

    def honk(self):
        print("Honk, Honk!")

    @property
    def axels(self) -> int:
        return int(wheels/2)

    def switch_lights(self) -> bool:
        self.lights = not self.lights

We can first generate a testing config for preview - if we use gridtest generate without an output file, it will print to the screen:

$ gridtest generate car.py
Extracting Car from car
Extracting honk from car
Extracting lights from car

car:
  filename: /home/vanessa/Desktop/Code/gridtest/examples/class/car.py
  tests:
    car.Car:
    - args:
        color: red
        lights: false
        wheels: 4
    car.Car.honk:
    - args:
        self: null
    car.Car.lights:
    - args:
        self: null

We can then write to file, and we’ll use the default name that gridtest can easily discover.

$ gridtest generate car.py gridtest.yml

Notice that we would want to be able to define an instance of a class to be used for the subsequent testing functions of the class. To do this, take the section you want to use, for example this one:

  car.Car:
  - args:
      color: red
      lights: false
      wheels: 4

and add an “instance” key to it.

  car.Car:
  - instance: thisone
    args:
      color: red
      lights: false
      wheels: 4

We now want to reference “thisone” as the instance to use. Just update the “self” variable in each of the class test cases.

car:
  filename: /home/vanessa/Desktop/Code/gridtest/examples/class/car.py
  tests:
    car.Car:
    - args:
        color: notacolor
        lights: false
        wheels: 4
      raises: ColorException
    - instance: thisone
      args:
        color: red
        lights: false
        wheels: 4
      isinstance: car.Car 
    car.Car.honk:
    - args:
        self: "{{ instance.thisone }}"
    car.Car.switch_lights:
    - args:
        self: "{{ instance.thisone }}"

And then the instance of the Car named as instance “this one” (the second block) will be used for those tests. This is a very basic usage for a class, and we expect more complex cases to be written up when they are determined.

Testing

Now, we can run tests! Since we’ve named the testing file gridtest.yml we can just run:

$ gridtest test
[4/4] |===================================| 100.0% 
Name                           Status                         Summary                       
________________________________________________________________________________________________________________________
car.Car.0                      success                        raises ColorException         
car.Car.1                      success                        isinstance Car                
car.Car.honk.0                 success                                                      
car.Car.switch_lights.0        success                                                      

4/4 tests passed

You might next want to browse other tutorials available.