diagrams

Type Members

trait Diagrams extends Assertions

Sub-trait of Assertions that overrides assert and assume methods to include a diagram showing the values of expression in the error message when the assertion or assumption fails.

Here are some examples:

scala> import org.scalatest.diagrams.Diagrams._
import org.scalatest.diagrams.Diagrams._

scala> assert(a == b || c >= d)
org.scalatest.exceptions.TestFailedException:

assert(a == b || c >= d)
       | |  | |  | |  |
       1 |  2 |  3 |  4
         |    |    false
         |    false
         false

        at org.scalatest.Assertions$class.newAssertionFailedException(Assertions.scala:422)
        ...

scala> assert(xs.exists(_ == 4))
org.scalatest.exceptions.TestFailedException:

assert(xs.exists(_ == 4))
       |  |
       |  false
       List(1, 2, 3)

        at org.scalatest.Assertions$class.newAssertionFailedException(Assertions.scala:422)
        ...

scala> assert("hello".startsWith("h") && "goodbye".endsWith("y"))
org.scalatest.exceptions.TestFailedException:

assert("hello".startsWith("h") && "goodbye".endsWith("y"))
       |       |          |    |  |         |        |
       "hello" true       "h"  |  "goodbye" false    "y"
                               false

        at org.scalatest.Assertions$class.newAssertionFailedException(Assertions.scala:422)
        ...

scala> assert(num.isInstanceOf[Int])
org.scalatest.exceptions.TestFailedException:

assert(num.isInstanceOf[Int])
       |   |
       1.0 false

        at org.scalatest.Assertions$class.newAssertionFailedException(Assertions.scala:422)
        ...

scala> assert(Some(2).isEmpty)
org.scalatest.exceptions.TestFailedException:

assert(Some(2).isEmpty)
       |    |  |
       |    2  false
       Some(2)

        at org.scalatest.Assertions$class.newAssertionFailedException(Assertions.scala:422)
        ...

scala> assert(None.isDefined)
org.scalatest.exceptions.TestFailedException:

assert(None.isDefined)
       |    |
       None false

        at org.scalatest.Assertions$class.newAssertionFailedException(Assertions.scala:422)
        ...

scala> assert(xs.exists(i => i > 10))
org.scalatest.exceptions.TestFailedException:

assert(xs.exists(i => i > 10))
       |  |
       |  false
       List(1, 2, 3)

        at org.scalatest.Assertions$class.newAssertionFailedException(Assertions.scala:422)
        ...

If the expression passed to assert or assume spans more than one line, Diagrams falls back to the default style of error message, since drawing a diagram would be difficult. Here's an example showing how Diagrams will treat a multi-line assertion (i.e., you don't get a diagram):

scala> assert("hello".startsWith("h") &&
     |   "goodbye".endsWith("y"))
org.scalatest.exceptions.TestFailedException: "hello" started with "h", but "goodbye" did not end with "y"
        at org.scalatest.Assertions$class.newAssertionFailedException(Assertions.scala:422)
        ...

Also, since an expression diagram essentially represents multi-line ascii art, if a clue string is provided, it appears above the diagram, not after it. It will often also show up in the diagram:

scala> assert(None.isDefined, "Don't do this at home")
org.scalatest.exceptions.TestFailedException: Don't do this at home

assert(None.isDefined, "Don't do this at home")
       |    |
       None false

        at org.scalatest.Assertions$class.newAssertionFailedException(Assertions.scala:422)
        ...

scala> assert(None.isDefined,
     |   "Don't do this at home")
org.scalatest.exceptions.TestFailedException: Don't do this at home

assert(None.isDefined,
       |    |
       None false

        at org.scalatest.Assertions$class.newAssertionFailedException(Assertions.scala:422)
        ...

Trait Diagrams was inspired by Peter Niederwieser's work in Spock and Expecty.

Value Members

object Diagrams extends Diagrams

Companion object that facilitates the importing of Diagrams members as an alternative to mixing it in.

Companion object that facilitates the importing of Diagrams members as an alternative to mixing it in. One use case is to import Diagrams members so you can use them in the Scala interpreter:

$scala -classpath scalatest.jar
Welcome to Scala version 2.10.4.final (Java HotSpot(TM) Client VM, Java 1.6.0_45).
Type in expressions to have them evaluated.
Type :help for more information.
 
scala> import org.scalatest.Assertions._
import org.scalatest.Assertions._
 
scala> assert(1 === 2)
org.scalatest.exceptions.TestFailedException:

assert(1 === 2)
       | |   |
       1 |   2
         false

     at org.scalatest.Assertions$class.newAssertionFailedException(Assertions.scala:422)
	    at org.scalatest.Diagrams$.newAssertionFailedException(Diagrams.scala:249)
	    at org.scalatest.Diagrams$DiagramsHelper.macroAssert(Diagrams.scala:111)
	    at .<init>(<console>:20)
	    at .<clinit>(<console>)
	    at .<init>(<console>:7)
	    at .<clinit>(<console>)
 	  at $print(<console>)
	    at sun.reflect.NativeMethodAccessorImpl.invoke...

package diagrams

Type Members

trait Diagrams extends Assertions

Value Members

object Diagrams extends Diagrams

Inherited from AnyRef

Inherited from Any

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