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Pytest's markers can, in addition to altering test behaviour, also filter tests. Pytest's markers are Python decorators starting with the @pytest. mark.< markername > syntax placed on top of test functions. With different arbitrarily named markers, running pytest -m <markername> on the command line will only run those tests decorated with such ...
Assertions are often enabled during development and disabled during final testing and on release to the customer. Not checking assertions avoids the cost of evaluating the assertions while (assuming the assertions are free of side effects) still producing the same result under normal conditions. Under abnormal conditions, disabling assertion ...
In Python, non-innermost-local and not-declared-global accessible names are all aliases. Among dynamically-typed languages, Python is moderately type-checked. Implicit conversion is defined for numeric types (as well as booleans), so one may validly multiply a complex number by an integer (for instance) without explicit casting.
These examples, one from mathematics and one from natural language, illustrate the concept of vacuous truths: "For any integer x, if x > 5 then x > 3." [11] – This statement is true non-vacuously (since some integers are indeed greater than 5), but some of its implications are only vacuously true: for example, when x is the integer 2, the statement implies the vacuous truth that "if 2 > 5 ...
The highlighted assertions within the loop body, at the beginning and end of the loop (lines 6 and 11), are exactly the same. They thus describe an invariant property of the loop. When line 13 is reached, this invariant still holds, and it is known that the loop condition i!=n from line 5 has become false.
Automated input minimization (or test case reduction) is an automated debugging technique to isolate that part of the failure-inducing input that is actually inducing the failure. [ 56 ] [ 57 ] If the failure-inducing input is large and mostly malformed, it might be difficult for a developer to understand what exactly is causing the bug.
Fallthrough behavior can be achieved with a sequence of if conditionals each without the else clause. A lookup table, which contains, as keys, the case values and, as values, the part under the case statement. (In some languages, only actual data types are allowed as values in the lookup table.
# This function has no guard clause def f_noguard (x): if isinstance (x, int): #code #code #code return x + 1 else: return None # Equivalent function with a guard clause. Note that most of the code is less indented, which makes it easier to read and reason about def f_guard (x): if not isinstance (x, int): return None #code #code #code return x + 1