# Random Number Tests

Testing code that includes random numbers can be hard.  Luckily, the random module comes with the `seed()` function. 

The `seed()` function allows you to initialize the random number generator with a specific value , which forces it to produce the same values each time. 

## Example 1 - Student Function

In this example, students are supposed to create a function named `make_random_numbers()` which returns a list of 10 random numbers between 20 and 99 inclusive. 

#### **Grading Tests:**

```python
import unittest
import random

class CodingRoomsUnitTests(unittest.TestCase):

    def test_case1(self):
        import example
        random.seed(10)
        self.assertListEqual([93, 24, 74, 81, 93, 21, 46, 79, 82, 55], example.make_random_numbers())

    def test_case2(self):
        import example
        random.seed(55)
        self.assertListEqual([31, 45, 39, 58, 30, 43, 58, 31, 65, 80], example.make_random_numbers() )
    
    def test_case3(self):
        import example
        random.seed(2)
        self.assertListEqual([27, 31, 30, 66, 41, 59, 52, 97, 47, 97], example.make_random_numbers())

if __name__ == '__main__':
    unittest.main()
```

Notice that `random.seed()` is called, setting the randomly generated numbers to predetermined values, before you check if the functions return value equals the expected value. 

#### Sample Solution:

{% code title="example.py" %}

```python
import random

def make_random_numbers():
    numbers_list = []
    for num in range(10):
        numbers_list.append(random.randint(20,99))
    return numbers_list
```

{% endcode %}

## Example 2 - Random Seed for random.randint()

Even better, we can randomly generate the seed and make the test random each time!

This example expects the student to use the `randint()` function to generate and print a random numbers between 0 and 500.

**Grading Tests:**

```python
import unittest
import sys, io
import random

stdout = sys.stdout

class CodingRoomsUnitTests(unittest.TestCase):

    def setUp(self):
        global stdout
        stdout = sys.stdout
        sys.stdout = io.StringIO()

    def tearDown(self):
        global stdout
        sys.stdout = stdout
        
    def test_default_case(self):
        s = random.randint(1, 55)
        
        random.seed(s)
        import main
        output = sys.stdout.getvalue()

        random.seed(s)
        num = random.randint(0, 500)

        answer = str(num)
        student = output
        
        self.assertEqual(answer, student)

if __name__ == '__main__':
    unittest.main()
```

**Sample Solution:**

{% code title="example.py" %}

```python
import random

random_num = random.randint(0,500)

print(random_num)
```

{% endcode %}

## Example 3 - Random Seed for random.choice()

Here is another where the student needed to print a random item from a list they created named `student_list`.

**Grading Tests:**

```python
import unittest
import sys, io
import random

stdout = sys.stdout

class CodingRoomsUnitTests(unittest.TestCase):

    def setUp(self):
        global stdout
        stdout = sys.stdout
        sys.stdout = io.StringIO()

    def tearDown(self):
        global stdout
        sys.stdout = stdout
        
    def test_default_case(self):
        s = random.randint(1, 55)
        
        random.seed(s)
        import example
        
        output = sys.stdout.getvalue().strip("\n")
        student = output

        random.seed(s)
        answer = random.choice(example.student_list)
        
        self.assertEqual(answer, student)

if __name__ == '__main__':
    unittest.main()
```

**Sample Solution:**

{% code title="example.py" %}

```python
import random

student_list = ["first thing", "second thing", "third thing", "fourth thing"]

random_thing = random.choice(student_list)

print(random_thing)
```

{% endcode %}