1. 设计程序时,目标为 defensive programming(防错型编程)
- Write specifications for functions
- Modularize programs
- Check conditions on inputs/outputs (assertions)
TESTING/VALIDATION
• Compare input/output pairs to specification
• “It’s not working!”
• “How can I break my program?”
DEBUGGING
• Study events leading upto an error
• “Why is it not working?”
• “How can I fix myprogram?
2. 测试开始前:
- from the start, design code to ease this part
- break program into modules that can be tested and debugged individually
- document constraints on modules
- what do you expect the input to be? the output to be?
- document assumptions behind code design
3. 准备测试:
-
ensure code runs
• remove syntax errors
• remove static semantic errors
• Python interpreter can usually find these for you -
have a set of expected results
• an input set
• for each input, the expected output
4. 测试步骤
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5.测试处理:TESTING APPROACHES
- intuition about natural boundaries to the problem
def is_bigger(x, y):
""" Assumes x and y are ints
Returns True if y is less than x, else False """
can you come up with some natural partitions?
2. if no natural partitions, might do **random testing**
> - probability that code is correct increases with more tests
> - better options below
3. **black box testing**
• explore paths through specification
4. **glass box testing**
• explore paths through code
####GLASS BOX TESTING(黑盒测试)
- designed *without looking* at the code
- can be done by someone other than the implementer to
avoid some implementer biases
- testing can be reused if implementation changes
- paths through specification
• build test cases in different natural space partitions
• also consider boundary conditions (empty lists, singleton
list, large numbers, small numbers)
####GLASS BOX TESTING
- use code directly to guide design of test cases
- called path-complete if every potential path through code is tested at least once
- what are some drawbacks of this type of testing?
• can go through loops arbitrarily many times
• missing paths
- guidelines
• branches
>exercise all parts of a conditional
• for loops
• while loop
