Step arguments

背景

看看 @given、@when、@when 的源码

def given(name, converters=None, target_fixture=None):
    """Given step decorator.
    :param name: Step name or a parser object.
    :param converters: Optional `dict` of the argument or parameter converters in form
                       {<param_name>: <converter function>}.
    :param target_fixture: Target fixture name to replace by steps definition function.
    :return: Decorator function for the step.
    """
    return _step_decorator(GIVEN, name, converters=converters, target_fixture=target_fixture)
def when(name, converters=None, target_fixture=None):
    """When step decorator.
    :param name: Step name or a parser object.
    :param converters: Optional `dict` of the argument or parameter converters in form
                       {<param_name>: <converter function>}.
    :param target_fixture: Target fixture name to replace by steps definition function.
    :return: Decorator function for the step.
    """
    return _step_decorator(WHEN, name, converters=converters, target_fixture=target_fixture)
def then(name, converters=None, target_fixture=None):
    """Then step decorator.
    :param name: Step name or a parser object.
    :param converters: Optional `dict` of the argument or parameter converters in form
                       {<param_name>: <converter function>}.
    :param target_fixture: Target fixture name to replace by steps definition function.
    :return: Decorator function for the step.
    """
    return _step_decorator(THEN, name, converters=converters, target_fixture=target_fixture)

类型

string（默认）

可以视为精确解析器，它不解析任何参数，根据提供的字符串精确匹配对应的步骤名称

parse（基于 pypi_parse）

• 提供一个简单的解析器，用像{param:Type}可读语法替换步骤参数的正则表达式
• 可以不提供类型 {username}
• 也可以提供类型{username:s}
• 这个类型和写 string.format(“%s”) 时，支持的类型一样，比如 %d、%s、%f

cfparse（基于 pypi_parse_type）

没看懂官方文档的解析，乱七八糟的描述

re

支持完整的正则表达式来解析步骤参数，必须用这个表达式(?P<name>…)

parse 的 🌰（比较常用）

parser.feature

Feature: Step arguments
    Scenario: Arguments for given, when, then
        Given there are 5 cucumbers
        When I eat 3 cucumbers
        And I eat 2 cucumbers
        Then I should have 0 cucumbers

test_parser.py

from pytest_bdd import scenario, given, when, then, parsers
@scenario("parser.feature", "Arguments for given, when, then")
def test_arguments():
    pass
@given(parsers.parse("there are {start:d} cucumbers"), target_fixture="cucumbers")
def given_cucumbers(start):
    print(start, type(start))
    return dict(start=start, eat=0)
@when(parsers.parse("I eat {eat} cucumbers"))
def eat_cucumbers(cucumbers, eat):
    print(eat, type("eat"))
    cucumbers["eat"] += int(eat)
@then(parsers.parse("I should have {left:d} cucumbers"))
def should_have_left_cucumbers(cucumbers, left):
    assert cucumbers['start'] - cucumbers['eat'] == left

命令行运行

pytest -sq test_parsers.py

运行结果

5 <class 'int'>
3 <class 'str'>
2 <class 'str'>
.
1 passed in 0.01s