[英]How would i go about handling multiple file exceptions?
基本上,我需要创建一个函数,该函数允许我从文件中加载计划行程的基本细节。 我们很简短:
参数:包含文件路径的字符串
返回值:3个字符串的字符串,其中包含从文件中读取的旅程的开始位置,结束位置和到达时间;如果失败,则返回(无,无,无)。
有多项测试,所有测试均使用幻数作为输入。 测试如下:
这是不良数据测试的代码,应为您提供以下测试之一的示例:
PATH = os.path.expanduser('~/test_prev_plan_spec.txt')
def test_missing_file_is_handled(self):
if os.path.exists(self.PATH):
os.unlink(self.PATH)
plan = utils.load_prev_plan_spec(self.PATH)
self.assertEqual(3, len(plan))
self.assertEqual(plan, (None, None, None))
def test_spec_loads_ok(self):
from_ = 'Bournemouth'
to = 'Southampton'
arrive_at = '2019/04/20 13:30'
with open(self.PATH, 'wt') as f:
f.write('{}\n{}\n{}\n'.format(from_, to, arrive_at))
plan = utils.load_prev_plan_spec(self.PATH)
self.assertEqual(3, len(plan))
self.assertEqual(from_, plan[0])
self.assertEqual(to, plan[1])
self.assertEqual(arrive_at, plan[2])
def test_short_spec_is_ignored(self):
from_ = 'Bournemouth'
to = 'Southampton'
with open(self.PATH, 'wt') as f:
f.write('{}\n{}\n'.format(from_, to))
plan = utils.load_prev_plan_spec(self.PATH)
self.assertEqual(3, len(plan))
self.assertEqual(plan, (None, None, None))
with open(self.PATH, 'wt') as f:
f.write('{}\n'.format(from_))
plan = utils.load_prev_plan_spec(self.PATH)
self.assertEqual(3, len(plan))
self.assertEqual(plan, (None, None, None))
def test_empty_line_is_handled(self):
from_ = 'Bournemouth'
to = ''
arrive_at = '2019/04/20 13:30'
with open(self.PATH, 'wt') as f:
f.write('{}\n{}\n{}\n'.format(from_, to, arrive_at))
plan = utils.load_prev_plan_spec(self.PATH)
self.assertEqual(3, len(plan))
self.assertEqual(plan, (None, None, None))
def test_bad_data_line_is_handled(self):
from_ = 'Bournemouth'
to = 'Southampton'
arrive_at = '2019/04/20 13:60'
with open(self.PATH, 'wt') as f:
f.write('{}\n{}\n{}\n'.format(from_, to, arrive_at))
plan = utils.load_prev_plan_spec(self.PATH)
self.assertEqual(3, len(plan))
self.assertEqual(plan, (None, None, None))
到目前为止,这是我所拥有的,我正在寻求与此相关的帮助,任何解释都很棒!
我的代码atm:
def load_prev_plan_spec(PATH):
'''
Function: utils.load_prev_plan_specLoads the basic details of a planned journey from a file.
Parameters: A string containing a file path
Returns: A 3-tuple of strings containing start location, end location and arrival time of a journey
read from the file, or (None, None, None) if unsuccessful.
'''
try:
if os.path.exists(PATH):
infomation = []
f = open(PATH, 'r', encoding='cp1252')
for line in f:
infomation.append([line.strip()])
if not line.strip():
infomation = (None, None, None)
tuple(infomation)
f.close()
return infomation
else:
pass
except IOError as err2:
print(err2)
raise IOError
else:
return infomation
第一次失败的测试是因为,如果第一行或第二行为空,则将具有三个None
值的元组绑定到infomation
,然后进行下一次迭代,然后尝试append()
某些内容append()
到该tuple中-但是元组没有append()
方法。 如果遇到空行,则需要停止处理这些行并返回错误值。
第二个失败的测试是因为您尝试在函数的最后一行中返回infomation
,但是如果文件不存在,则没有执行路径可以为此名称分配值。
第三次失败无法识别13:60
不是有效的时间值。
第四个失败返回两个值,而不是三个值,因为您不检查文件中是否实际上存在三行而不是更少。
第六个也是最后一个失败是因为您将每个项目包装在列表中。 为什么?
通过所有测试用例的函数可能如下所示:
from datetime import datetime as DateTime
def load_prev_plan_spec(path):
try:
with open(path, 'r', encoding='cp1252') as file:
lines = [line.strip() for line in file]
if len(lines) == 3 and all(lines):
try:
#
# Just for the `ValueError` to test if string is a valid
# timestamp.
#
DateTime.strptime(lines[-1], '%Y/%m/%d %H:%M')
except ValueError:
pass # Intentionally ignored.
else:
return tuple(lines)
except (OSError, UnicodeDecodeError):
pass # Intentionally ignored.
return (None, None, None)
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.