test_while_loop¶

test_while_loop(index=1, test=None, body=None, orelse=None, expand_message=True, state=None)¶

Test parts of the while loop.

This test function will allow you to extract parts of a specific while loop and perform a set of tests specifically on these parts. A while loop generally consists of two parts: the condition test, test, which is the condition that is tested each loop, and the body. A for while can have a else part as well, orelse, but this is almost never used.:

a = 10
while a < 5:
    print(a)
    a -= 1

Has a < 5 as the condition test and print(i) as the body.

Parameters:

index (int) – index of the function call to be checked. Defaults to 1.
test – this argument holds the part of code that will be ran to check the condition test of the while loop. It should be passed as a lambda expression or a function definition. The functions that are ran should be other pythonwhat test functions, and they will be tested specifically on only the condition test of the while loop.
body – this argument holds the part of code that will be ran to check the body of the while loop. It should be passed as a lambda expression or a function definition. The functions that are ran should be other pythonwhat test functions, and they will be tested specifically on only the body of the while loop.
orelse – this argument holds the part of code that will be ran to check the else part of the while loop. It should be passed as a lambda expression or a function definition. The functions that are ran should be other pythonwhat test functions, and they will be tested specifically on only the else part of the while loop.
expand_message (bool) – if true, feedback messages will be expanded with in the ___ of the while loop on line ___. Defaults to True. If False, test_for_loop() will generate no extra feedback.

Example:

Student code:

a = 10
while a < 5:
    print(a)
    a -= 1

Solution code:

a = 20
while a < 5:
    print(a)
    a -= 1

SCT:

test_while_loop(1,
        test = test_expression_result({"a": 5}),
        body = test_expression_output({"a": 5}))

This SCT will evaluate to True as condition test will have thes same result in student and solution code and test_exression_output() will pass on the body code.

test_while_loop(index=1,
                test=None,
                body=None,
                orelse=None,
                expand_message=True)

Since a lot of the logic of test_if_else() and test_for_loop() can be applied to test_while_loop(), this article is limited to an example. For more info see the wiki on test_if_else() and test_for_loop(), or the documentation of test_while_loop().

*** =solution
```{python}
a = 10
while a > 5:
  print("%s is bigger than 5" % a)
  a -= 1
```

*** =sct
```{python}
def sct_on_condition_test():
  test_expression_result({"a": 4})
  test_expression_result({"a": 5})
  test_expression_result({"a": 6})

test_while_loop(index = 1,
                test = sct_on_condition_test,
                body = lambda: test_expression_output({"a":4}))    
```