How does the ScalaTest syntax work?

Question

I did some programming in Scala, and I know that, for example,

xs map f

is the same as

xs.map(f)

but I don’t know how to generalize this syntax to something like ScalaTest syntax, for example

it should "throw NoSuchElementException if an empty stack is popped" in {
  val emptyStack = new Stack[String]
  evaluating { emptyStack.pop() } should produce [NoSuchElementException]
}

I am mainly interested in things that look like verbose constructs, namely should produce. This is neat.

Answer 1

This type of syntax is method calls in operator notation, but they carry over to more than three tokens. As you mentioned:

xs map f

funds:

xs.map(f)

But you can go further and say:

xs map f map g

What means:

xs.map(f).map(g)

For example, in ScalaTest mappers you can say:

result should not be null

This compiles using the compiler:

result.should(not).be(null)

It:

it should "throw an exception" in { ... }

falls into:

it.should("throw an exception").in { ... }

- ( ) in, . . .

, , :

evaluating { ... } should produce [IllegalArgumentException]

:

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, , :

(evaluating { ... }).should(produce[IllegalArgumentException] (compilerSuppliedManifest))

, , , . , , - , , - . Scala -Xprint:typer Scala, , . , , , , .

Answer 2

, - it should it.should, , ( ), it. !

ItWord, should, BehaveWord. ShouldMatchers trait.

ScalaTest , .