Python查找列表1中不在列表2中的元素-简单代码不工作

你所观察到的是因为 requirementWithCoverage 包含不在 allRequirements

allRequirements         = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
requirementWithCoverage = [1,                7,           11, 12] # 11 and 12 are unexpectedly there
notCovered              = list(set(allRequirements) - set(requirementWithCoverage))

print(len(allRequirements))          # 10
print(len(requirementWithCoverage))  #  4
print(len(notCovered))               #  8 (6 was expected)

您可以通过打印 set(requirementWithCoverage).issubset(set(allRequirements)) 这应该是错误的,而你期望它是正确的。
保险范围内的要求

print(set(requirementWithCoverage) - set(allRequirements))