Trait/Object

org.scalatest.enablers

Size

Related Docs: object Size | package enablers

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trait Size[T] extends AnyRef

Supertrait for Size typeclasses.

Trait Size is a typeclass trait for objects that can be queried for size. Objects of type T for which an implicit Size[T] is available can be used with the should have size syntax. In other words, this trait enables you to use the size checking syntax with arbitrary objects. As an example, consider java.net.DatagramPacket, which has a getSize method. By default, this can't be used with ScalaTest's have size syntax.

scala> import java.awt.image.DataBufferByte
import java.awt.image.DataBufferByte

scala> import org.scalatest.matchers.ShouldMatchers._
import org.scalatest.matchers.ShouldMatchers._

scala> val db = new DataBufferByte(4)
db: java.awt.image.DataBufferByte = java.awt.image.DataBufferByte@33d5e94f

scala> db.getSize
res0: Int = 4

scala> db should have size 4
:17: error: could not find implicit value for parameter ev: org.scalatest.matchers.ShouldMatchers.Extent[java.awt.image.DataBufferByte]
              db should have size 4
                 ^
scala> implicit val sizeOfDataBufferByte =
     |   new Size[DataBufferByte] {
     |     def sizeOf(db: DataBufferByte): Long = db.getSize
     |   }
sizeOfDataBufferByte: java.lang.Object with org.scalatest.matchers.ShouldMatchers.Size[java.awt.image.DataBufferByte] = $anon$1@4c69bdf8

scala> db should have size 4

scala> db should have size 3
org.scalatest.exceptions.TestFailedException:  java.awt.image.DataBufferByte@33d5e94f had size 4, not size 3

Source
Size.scala
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Abstract Value Members

  1. abstract def sizeOf(obj: T): Long

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    Returns the size of the passed object.

    Returns the size of the passed object.

    obj

    the object whose size to return

    returns

    the size of the passed object