org.scalatest.diagrams

A trait that represent an expression recorded by DiagrammedExprMacro, which includes the following members:

• a boolean value

• an anchor that records the position of this expression

• anchor values of this expression (including sub-expressions)

DiagrammedExpr is used by code generated from DiagrammedAssertionsMacro, it needs to be public so that the generated code can be compiled. It is expected that ScalaTest users would ever need to use DiagrammedExpr directly.

DiagrammedExpr companion object that provides factory methods to create different sub types of DiagrammedExpr

DiagrammedExpr is used by code generated from DiagrammedAssertionsMacro, it needs to be public so that the generated code can be compiled. It is expected that ScalaTest users would ever need to use DiagrammedExpr directly.

Sub-trait of Assertions that override 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 DiagrammedAssertions._
import DiagrammedAssertions._

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, DiagrammedAssertions falls back to the default style of error message, since drawing a diagram would be difficult. Here's an example showing how DiagrammedAssertions 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 DiagrammedAssertions was inspired by Peter Niederwieser's work in Spock and Expecty.

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

$scala -classpath scalatest.jar
Welcome to Scala 2.13.6 (OpenJDK 64-Bit Server VM, Java yyy).
Type in expressions for evaluation. Or try :help.
 
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$class.newAssertionFailedException(Assertions.scala:422)
    at org.scalatest.DiagrammedAssertions$.newAssertionFailedException(DiagrammedAssertions.scala:249)
    at org.scalatest.DiagrammedAssertions$DiagrammedAssertionsHelper.macroAssert(DiagrammedAssertions.scala:111)
    at .<init>(<console>:20)
    at .<clinit>(<console>)
    at .<init>(<console>:7)
    at .<clinit>(<console>)
	  at $print(<console>)
    at sun.reflect.NativeMethodAccessorImpl.invoke...