http://behat.org/en/latest/user_guide/context/definitions.html
------------定义步骤--------------
当Behat运行时，它会比较每个场景中的Gherkin步骤行与FeatureContext中每个方法绑定的模式。
如果Gherkin线满足绑定模式，则执行相应的步骤定义。
Behat 使用 php-doc 注释将模式绑定到 FeatureContext 方法：
<pre class="lang:default decode:true "><?php
/**
* @When I do something with :methodArgument
*/
public function someMethod($methodArgument) {}
?></pre>
（注意注释块以/ **开始，而不是通常的/ *。这对于Behat来说是很重要的，以便能够解析注释的注释！）
1、@Given @When @Then 关键词是等效的，都可以随便使用。推荐按语义使用，方便阅读。
2、:后面的关键词是令牌 token，所有的令牌将会被当做对应的变量传入(:methodArgument -> $methodArgument)
<pre class="lang:default decode:true ">#feature
Given I do something with "string1"
When I do something with 'some other string'
Then I do something with 25</pre>
执行结果等于以下效果：
<pre class="lang:default decode:true">$context->someMethod($methodArgument = 'string1');
$context->someMethod($methodArgument = 'some other string');
$context->someMethod($methodArgument = '25');</pre>
(当匹配模式与方法时，Behat不区分步骤关键字。所以与@When定义的一个步骤也可以匹配 @Given ...，@Then ...，@And ...，@But ...等)
绑定模式写法：
1)可以支持传入多个参数:
<pre class="lang:default decode:true "><?php
/**
* @When I do something with :stringArgument and with :numberArgument
*/
public function someMethod($stringArgument, $numberArgument) {}
?></pre>
2)指定单词多选方法，例如：is/are，there is xxxx 和 there are xxx 都可以匹配到
<pre class="lang:default decode:true"><?php
/**
* @When there is/are :count monster(s)
*/
public function thereAreMonsters($count) {
echo 'thereAreMonsters->count:'.$count;
}
?></pre>
<pre class="lang:default decode:true ">#feature
Feature: You can also specify alternative words and optional parts of words
Scenario: test 1
Given there is 1 monster
Then there are 3 monsters</pre>
输出：
<pre class="lang:default decode:true ">[behat]$ vendor/bin/behat features/default/or.feature
Feature: You can also specify alternative words and optional parts of words
Scenario: test 1 # features/default/or.feature:2
Given there is 1 monster # FeatureContext::thereAreMonsters()
│ thereAreMonsters->count:1
Then there are 3 monsters # FeatureContext::thereAreMonsters()
│ thereAreMonsters->count:3
1 scenario (1 passed)
2 steps (2 passed)
0m0.04s (13.11Mb)</pre>
3)正则匹配方法
<pre class="lang:default decode:true "><?php
/**
* @When /^there (?:have|had) (\d+) monsters?$/i
*/
public function thereAreMonsters2($count) {
echo 'thereAreMonsters2->count:'.$count;
}
?></pre>
<pre class="lang:default decode:true ">#feature
Feature: You can also specify alternative words and optional parts of words
Scenario: test 1
When there have 1 monster
When there had 6 monsters</pre>
输出：
<pre class="lang:default decode:true ">[behat]$ vendor/bin/behat features/default/or.feature
Feature: You can also specify alternative words and optional parts of words
Scenario: test 1 # features/default/or.feature:2
When there have 1 monster # FeatureContext::thereAreMonsters2()
│ thereAreMonsters2->count:1
When there had 6 monsters # FeatureContext::thereAreMonsters2()
│ thereAreMonsters2->count:6
1 scenario (1 passed)
4 steps (4 passed)
0m0.04s (13.12Mb)</pre>
------------定义片段-----definition snippets-------
自动在 Context 类里面，定义片段
先创建一个 feature 文件:
example.feature
<pre class="lang:default decode:true">Feature:
Scenario:
Given some step with "string" argument
And number step with 23</pre>
假设这个 feature 在套件配置里面，指向的是 FeatureContext.php 且在这个文件里面没有设置对应的片段匹配。
执行命令：
<pre class="lang:default decode:true ">[behat]$ vendor/bin/behat features/default/example.feature --dry-run --append-snippets
Feature:
Scenario: # features/default/example.feature:2
Given some step with "string" argument
And number step with 23
1 scenario (1 undefined)
2 steps (2 undefined)
0m0.02s (12.88Mb)
>> default suite has undefined steps. Please choose the context to generate snippets:
[0] None
[1] FeatureContext
> 1
u features/bootstrap/FeatureContext.php - `some step with "string" argument` definition added
u features/bootstrap/FeatureContext.php - `number step with 23` definition added</pre>
会让你选择在哪个 Context 类添加片段，选择1后，将会在 FeatureContext.php 里面添加了简单的片段，如下：
<pre class="lang:default decode:true "><?php
//...
/**
* @Given some step with :arg1 argument
*/
public function someStepWithArgument($arg1)
{
throw new PendingException();
}
/**
* @Given number step with :arg1
*/
public function numberStepWith($arg1)
{
throw new PendingException();
}
?></pre>
这就完成了自动创建片段。