ScalaTest——日志打印

布满荆棘的人生 2022-05-12 15:10 254阅读 0赞

##### 5.1 Informers日志 #####

Informer在`ScalaTest`中是为了打印日志方便观察，跟`debug`语句很相似，但它可以放在任何地方来输出一些跟测试相关的信息。使用Informer只要调用`info(String)`方法即可。如下面的例子：

import org.scalatest.{FunSpec, ShouldMatchers}
    
    class AlbumTest extends FunSpec with ShouldMatchers {
      describe("An Album") {
        it("can add an Artist object to the album") {
          val album = new Album("Thriller", 1981, new Artist("Michael", "Jackson"))
          info("Test firstName should be Michael")
          album.artist.firstName should be("Thriller")
        }
      }
    }

运行测试，得到如下输出结果：

[info] AlbumTest:
    [info] An Album 
    [info] - can add an Artist object to the album
    [info]   + Test firstName should be Michael 
    [info] Run completed in 231 milliseconds.
    [info] Total number of tests run: 1
    [info] Suites: completed 1, aborted 0
    [info] Tests: succeeded 1, failed 0, canceled 0, ignored 0, pending 0
    [info] All tests passed.
    [success] Total time: 0 s, completed May 19, 2015 9:19:28 PM

可以和`简单的例子`中的输出结果进行比较，发现在`第4行`多出了一个`+ Test firstName should be Michael`，这里就是Informer的输出了，以`+`开头。

##### 5.2 GivenWhenThen日志 #####

在了解了Informer之后，GivenWhenThen就比较简单了。也是为了打印一些信息，以便观察哪里出问题了，类似于打印日志。

实际上，任何一个过程者可以被描述为`Given`－－`When`－－`Then`。`Given`相当于所给的前置条件，`When`相当于产生了某个动作或处于某种条件下，`Then`表示前面两个条件产生的结果。如下面的例子：

import core.{Artist, Album}
    import org.scalatest.{GivenWhenThen, ShouldMatchers, FunSpec}
    
    class AlbumSpec extends FunSpec with ShouldMatchers with GivenWhenThen {
      describe("An Album") {
        it("can add an Artist to the album at construction time") {
          Given("The album Thriller by Michael Jackson")
          val album = new Album("Thriller", 1981, new Artist("Michael", "Jackson"))
    
          When("the album\'s artist is obtained")
          val artist = album.artist
    
          Then("the artist obtained should be an instance of Artist")
          artist.isInstanceOf[Artist] should be(true)
    
          and("the artist's first name and last name should be Michael Jackson")
          artist.firstName should be("Michael")
          artist.lastName should be("Jackson")
        }
    }

运行上面的测试，将产生如下的结果：

[info] AlbumSpec:
    [info] An Album
    [info] - can add an Artist to the album at construction time
    [info]   + Given The album Thriller by Michael Jackson 
    [info]   + When the album's artist is obtained 
    [info]   + Then the artist obtained should be an instance of Artist 
    [info]   + And the artist's first name and last name should be Michael Jackson 
    [info] Run completed in 216 milliseconds.
    [info] Total number of tests run: 1
    [info] Suites: completed 1, aborted 0
    [info] Tests: succeeded 1, failed 0, canceled 0, ignored 0, pending 0
    [info] All tests passed.
    [success] Total time: 0 s, completed May 19, 2015 9:31:47 PM

可以看到`Given`、`When`、`Then`、`and`里面的字符串都是以Informer的形式输出的，使用一个`and`将测试的内容分开了，加强了可读性。而`GivenWhenThen`是一个特质，可以被混入任何的类。`GivenWhenThen`使测试变得结构化，使得在测试时可以很好的组织思想。