安装
cucumber是一款测试工具。可用于大多数主流编程语言。比如JAVA、JS、Ruby、C++、Lua、Android、Kotlin、C#/F#、PHP、Python、Go、Groovy、Scala等等。其中JAVA、JS、Ruby的代码托管在cucumber下。官方建议选择与生产代码相同的平台或编程语言的实现。本文主要是JAVA平台下的介绍教程。使用方法非常简单，创建一个mvn工程，在pom.xml文件引入以下依赖即可。
io.cucumber
cucumber-java8
4.2.0
test
也可以根据骨架创建cucumber项目。
创建一个空的Cucumber项目
我们首先使用cucumber- prototype Maven插件创建一个新项目目录。打开终端，转到要创建项目的目录（比如本文是hellocucumber)，运行以下命令:
mvn archetype:generate \
-DarchetypeGroupId=io.cucumber \
-DarchetypeArtifactId=cucumber-archetype \
-DarchetypeVersion=2.3.1.2 \
-DgroupId=hellocucumber \
-DartifactId=hellocucumber \
-Dpackage=hellocucumber \
-Dversion=1.0.0-SNAPSHOT \
-DinteractiveMode=false
你应该得到如下结果:
[INFO] Project created from Archetype in dir: hellocucumber/cucumber
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
切换到刚才运行命令创建的目录:
cd hellocucumber
在IntelliJ IDEA(或者eclipse都行）中打开项目:
- 文件->打开…->(选择pom.xml)
- 选择Open as Project
现在，您已经安装了一个简单的Cucumber项目。
验证cucumber安装
mvn test
您应该看到如下内容:
-------------------------------------------------------
T E S T S
-------------------------------------------------------
Running hellocucumber.RunCucumberTest
No features found at [classpath:hellocucumber]
0 Scenarios
0 Steps
0m0.004s
Tests run: 0, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.541 sec
Results :
Tests run: 0, Failures: 0, Errors: 0, Skipped: 0
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
Cucumber的输出告诉我们它没有找到任何可以运行的东西。
写一个Scenario（场景）
当我们使用Cucumber进行行为驱动开发时，我们使用具体的例子来指定我们希望软件做什么。Scenario是在生产代码之前编写的。它们以可执行规范的形式开始生命。随着生产代码的出现，场景扮演了事实文档和自动化测试的角色。
在Cucumber中，一个example称为Scenario。Scenario定义在.feature文件中，这些文件存储在src/test/resources/hellocucumber目录(或子目录)中。
一个具体的例子就是：星期天不是星期五。
创建一个名为src/test/resources/hellocucumber/is_it_friday_yet.feature的文件，文件包括以下内容:
Feature: Is it Friday yet?
Everybody wants to know when it's Friday
Scenario: Sunday isn't Friday
Given today is Sunday
When I ask whether it's Friday yet
Then I should be told "Nope"
这个文件的第一行以关键字'''Feature'''开始:后面跟着一个名称。最好使用与文件名类似的名称。
第二行是对该特性的简要描述。Cucumber并不执行这一行，它只是一个文档。
第4行，场景:Sunday is not Friday是一个scenario，它是说明软件应该如何工作的具体示例。
最后三行以Given开头，When和Then是我们的场景的步骤。这就是Cucumber将要执行的操作。
看一个未定义的scenario报告
现在我们有了一个场景，我们可以让Cucumber执行它：
mvn test
Cucumber告诉我们有一个undefined的场景和三个undefined的步骤。它还建议我们使用一些代码片段来define这些步骤:
-------------------------------------------------------
T E S T S
-------------------------------------------------------
Running hellocucumber.RunCucumberTest
Feature: Is it Friday yet?
Everybody wants to know when it's Friday
Scenario: Sunday isn't Friday # hellocucumber/is_it_friday_yet.feature:4
Given today is Sunday # null
When I ask whether it's Friday yet # null
Then I should be told "Nope" # null
1 Scenarios (1 undefined)
3 Steps (3 undefined)
0m0.040s
You can implement missing steps with the snippets below:
@Given("^today is Sunday$")
public void today_is_Sunday() {
// Write code here that turns the phrase above into concrete actions
throw new PendingException();
}
@When("^I ask whether it's Friday yet$")
public void i_ask_whether_it_s_Friday_yet() {
// Write code here that turns the phrase above into concrete actions
throw new PendingException();
}
@Then("^I should be told \"([^\"]*)\"$")
public void i_should_be_told(String arg1) {
// Write code here that turns the phrase above into concrete actions
throw new PendingException();
}
复制以上未定义步骤的三个代码片段：
@Given("^today is Sunday$")
public void today_is_Sunday() {
// Write code here that turns the phrase above into concrete actions
throw new PendingException();
}
@When("^I ask whether it's Friday yet$")
public void i_ask_whether_it_s_Friday_yet() {
// Write code here that turns the phrase above into concrete actions
throw new PendingException();
}
@Then("^I should be told \"([^\"]*)\"$")
public void i_should_be_told(String arg1) {
// Write code here that turns the phrase above into concrete actions
throw new PendingException();
}
并将它们粘贴到src/test/java/hellocucumber/steps.java中。
看一个pending的scenario报告
再次运行Cucumber: mvn test。这次的输出略有不同:
-------------------------------------------------------
T E S T S
-------------------------------------------------------
Running hellocucumber.RunCucumberTest
Feature: Is it Friday yet?
Everybody wants to know when it's Friday
Scenario: Sunday isn't Friday # hellocucumber/is_it_friday_yet.feature:4
Given today is Sunday # Stepdefs.today_is_Sunday()
cucumber.api.PendingException: TODO: implement me
at hellocucumber.Stepdefs.today_is_Sunday(Stepdefs.java:12)
at ✽.today is Sunday(hellocucumber/is_it_friday_yet.feature:5)
When I ask whether it's Friday yet # Stepdefs.i_ask_whether_it_s_Friday_yet()
Then I should be told "Nope" # Stepdefs.i_should_be_told(String)
1 Scenarios (1 pending)
3 Steps (2 skipped, 1 pending)
0m0.188s
cucumber.api.PendingException: TODO: implement me
at hellocucumber.Stepdefs.today_is_Sunday(Stepdefs.java:12)
at ✽.today is Sunday(hellocucumber/is_it_friday_yet.feature:5)
Cucumber找到我们的步骤定义并执行它们。它们当前被标记为pending，这意味着我们需要让它们做一些有用的事情。
看一个falling的scenario报告
下一步是按照步骤定义中的注释所告诉我们的去做:
Write code here that turns the phrase above into concrete actions
尝试在代码中使用与步骤中相同的单词。
将步骤定义代码更改为:
package hellocucumber;
import cucumber.api.java.en.Given;
import cucumber.api.java.en.When;
import cucumber.api.java.en.Then;
import static org.junit.Assert.*;
class IsItFriday {
static String isItFriday(String today) {
return null;
}
}
public class Stepdefs {
private String today;
private String actualAnswer;
@Given("^today is Sunday$")
public void today_is_Sunday() {
today = "Sunday";
}
@When("^I ask whether it's Friday yet$")
public void i_ask_whether_is_s_Friday_yet() {
actualAnswer = IsItFriday.isItFriday(today);
}
@Then("^I should be told \"([^\"]*)\"$")
public void i_should_be_told(String expectedAnswer) {
assertEquals(expectedAnswer, actualAnswer);
}
}
再次运行mvn test :
-------------------------------------------------------
T E S T S
-------------------------------------------------------
Running hellocucumber.RunCucumberTest
Feature: Is it Friday yet?
Everybody wants to know when it's Friday
Scenario: Sunday isn't Friday # hellocucumber/is_it_friday_yet.feature:4
Given today is Sunday # Stepdefs.today_is_Sunday()
When I ask whether it's Friday yet # Stepdefs.i_ask_whether_is_s_Friday_yet()
Then I should be told "Nope" # Stepdefs.i_should_be_told(String)
java.lang.AssertionError: expected: but was:
at org.junit.Assert.fail(Assert.java:88)
at org.junit.Assert.failNotEquals(Assert.java:834)
at org.junit.Assert.assertEquals(Assert.java:118)
at org.junit.Assert.assertEquals(Assert.java:144)
at hellocucumber.Stepdefs.i_should_be_told(Stepdefs.java:30)
at ✽.I should be told "Nope"(hellocucumber/is_it_friday_yet.feature:7)
Failed scenarios:
hellocucumber/is_it_friday_yet.feature:4 # Sunday isn't Friday
1 Scenarios (1 failed)
3 Steps (1 failed, 2 passed)
0m0.404s
这就是进步! 但前两步已经passing，最后一步却failing了。
看一个passing的scenario报告
让我们做最简单的事情来让场景通过。在本例中，这只是为了让我们的方法返回Nope :
static String isItFriday(String today) {
return "Nope";
}
再次运行mvn test:
-------------------------------------------------------
T E S T S
-------------------------------------------------------
Running hellocucumber.RunCucumberTest
Feature: Is it Friday yet?
Everybody wants to know when it's Friday
Scenario: Sunday isn't Friday # hellocucumber/is_it_friday_yet.feature:4
Given today is Sunday # Stepdefs.today_is_Sunday()
When I ask whether it's Friday yet # Stepdefs.i_ask_whether_is_s_Friday_yet()
Then I should be told "Nope" # Stepdefs.i_should_be_told(String)
1 Scenarios (1 passed)
3 Steps (3 passed)
0m0.255s
恭喜你!这是第一个成功(passing)的Cucumber Scenario。
添加另一个失败的测试
下一件要测试的事情是，我们也会在周五得到正确的结果。
更新is-it-friday-yet.feature文件:
Feature: Is it Friday yet?
Everybody wants to know when it's Friday
Scenario: Sunday isn't Friday
Given today is Sunday
When I ask whether it's Friday yet
Then I should be told "Nope"
Scenario: Friday is Friday
Given today is Friday
When I ask whether it's Friday yet
Then I should be told "TGIF"
我们需要添加一个步骤定义，将today设置为“Friday”:
@Given("^today is Friday$")
public void today_is_Friday() {
this.today = "Friday";
}
当我们运行这个测试时，它将失败。
Running hellocucumber.RunCucumberTest
Feature: Is it Friday yet?
Everybody wants to know when it's Friday
Scenario: Sunday isn't Friday # hellocucumber/isitfriday.feature:4
Given today is "Sunday" # Stepdefs.today_is(String)
When I ask whether is's Friday yet # Stepdefs.i_ask_whether_is_s_Friday_yet()
Then I should be told "Nope" # Stepdefs.i_should_be_told(String)
Scenario: Friday is Friday # hellocucumber/is_it_friday.feature:9
Given today is "Friday" # Stepdefs.today_is(String)
When I ask whether is's Friday yet # Stepdefs.i_ask_whether_is_s_Friday_yet()
Then I should be told "TGIF" # Stepdefs.i_should_be_told(String)
org.junit.ComparisonFailure: expected:<[TGIF]> but was:<[Nope]>
at org.junit.Assert.assertEquals(Assert.java:115)
at org.junit.Assert.assertEquals(Assert.java:144)
at hellocucumber.Stepdefs.i_should_be_told(Stepdefs.java:26)
at ✽.I should be told "TGIF"(hellocucumber/is_it_friday.feature:12)
org.junit.ComparisonFailure:
Expected :TGIF
Actual :Nope
at org.junit.Assert.assertEquals(Assert.java:115)
at org.junit.Assert.assertEquals(Assert.java:144)
at hellocucumber.Stepdefs.i_should_be_told(Stepdefs.java:26)
at ✽.I should be told "TGIF"(hellocucumber/is_it_friday.feature:12)
那是因为我们还没有实现逻辑!我们接着做。
让它通过
我们应该更新我们的语句来实际评估Today是否等于“Friday”。
static String isItFriday(String today) {
if (today.equals("Friday")) {
return "TGIF";
}
return "Nope";
}
再次运行mvn test:
-------------------------------------------------------
T E S T S
-------------------------------------------------------
Running hellocucumber.RunCucumberTest
Feature: Is it Friday yet?
Everybody wants to know when it's Friday
Scenario: Friday is Friday # hellocucumber/is_it_friday_yet.feature:4
Given today is Friday # Stepdefs.today_is_Sunday()
When I ask whether it's Friday yet # Stepdefs.i_ask_whether_is_s_Friday_yet()
Then I should be told "TGIF" # Stepdefs.i_should_be_told(String)
Scenario: Sunday isn't Friday # hellocucumber/is_it_friday_yet.feature:4
Given today is Sunday # Stepdefs.today_is_Sunday()
When I ask whether it's Friday yet # Stepdefs.i_ask_whether_is_s_Friday_yet()
Then I should be told "Nope" # Stepdefs.i_should_be_told(String)
2 scenarios (2 passed)
6 steps (6 passed)
0m0.255s
使用变量和实例
所以，我们都知道一周中不止周日和周五。让我们更新我们的scenario以使用变量并评估更多的可能性。我们将使用变量和示例来计算星期五、星期天和其他任何时间!
更新is-it-friday-yet.feature文件。注意，当我们开始使用多个Examples时，我们是如何从一个Scenario切换到Scenario Outline的。
Feature: Is it Friday yet?
Everybody wants to know when it's Friday
Scenario Outline: Today is or is not Friday
Given today is ""
When I ask whether it's Friday yet
Then I should be told ""
Examples:
| day | answer |
| Friday | TGIF |
| Sunday | Nope |
| anything else! | Nope |
我们需要用一个以today is Sunday和today is Friday的步骤定义。更新stepdefs.java文件如下:
package hellocucumber;
import cucumber.api.java.en.Given;
import cucumber.api.java.en.When;
import cucumber.api.java.en.Then;
import static org.junit.Assert.*;
class IsItFriday {
static String isItFriday(String today) {
if (today.equals("Friday")) {
return "TGIF";
}
return "Nope";
}
}
public class Stepdefs {
private String today;
private String actualAnswer;
@Given("^today is \"([^\"]*)\"$")
public void today_is(String today) {
this.today = today;
}
@When("^I ask whether it's Friday yet$")
public void i_ask_whether_is_s_Friday_yet() {
this.actualAnswer = IsItFriday.isItFriday(today);
}
@Then("^I should be told \"([^\"]*)\"$")
public void i_should_be_told(String expectedAnswer) {
assertEquals(expectedAnswer, actualAnswer);
}
}
再次执行mvn test:
-------------------------------------------------------
T E S T S
-------------------------------------------------------
Running hellocucumber.RunCucumberTest
Feature: Is it Friday yet?
Everybody wants to know when it's Friday
Scenario Outline: Today is or is not Friday # hellocucumber/is_it_friday_yet.feature:4
Given today is # hellocucumber/is_it_friday_yet.feature:5
When I ask whether it's Friday yet # hellocucumber/is_it_friday_yet.feature:6
Then I should be told # hellocucumber/is_it_friday_yet.feature:7
Scenario: Sunday isn't Friday # hellocucumber/is_it_friday_yet.feature:4
Given today is Sunday # Stepdefs.today_is_Sunday()
When I ask whether it's Friday yet # Stepdefs.i_ask_whether_is_s_Friday_yet()
Then I should be told "Nope" # Stepdefs.i_should_be_told(String)
Examples:
| day | answer |
| "Friday" | "TGIF" |
| "Sunday" | "Nope" |
| "anything else!" | "Nope" |
3 scenarios (3 passed)
9 steps (9 passed)
0m0.255s
重构
现在我们有了工作代码，我们应该做一些重构:
- 我们应该将
isItFriday方法从测试代码移到生产代码中。 - 我们可以在某个时候从步骤定义中提取helper方法，用于我们在几个地方使用的方法。
总结
在这个简短的教程中，您已经了解了如何安装Cucumber，如何遵循BDD流程来开发一个非常简单的方法，以及如何使用该方法来评估多个场景!
附录
英文原文：https://docs.cucumber.io/guides/10-minute-tutorial/#create-an-empty-cucumber-project