Scala Expect

A Scala implementation of a very small subset of the widely known TCL expect.

Scala Expect comes with three different flavors: core, fluent and dsl.

Install

libraryDependencies += "work.martins.simon" %% "scala-expect" % "6.0.0"

Core

Documentation

Advantages

• Closer to metal / basis for the other flavors.
• Immutable and therefore thread-safe.
• Most errors will be caught at compile time (eg. you won't be able to use a SendWithRegex inside a StringWhen).

Disadvantages

• Verbose syntax.
• Can't cleanly add expect blocks/whens/actions based on a condition.

Example

import work.martins.simon.core._
import scala.concurrent.ExecutionContext.Implicits.global

val e = new Expect("bc -i", defaultValue = 5)(
  ExpectBlock(
    StringWhen("For details type `warranty'.")(
      Sendln("1 + 2")
    )
  ),
  ExpectBlock(
    RegexWhen("""\n(\d+)\n""".r)(
      SendlnWithRegex { m =>
        val previousAnswer = m.group(1)
        println(s"Got $previousAnswer")
        s"$previousAnswer + 3"
      }
    )
  ),
  ExpectBlock(
    RegexWhen("""\n(\d+)\n""".r)(
      ReturningWithRegex(_.group(1).toInt)
    )
  )
)
e.run() //Returns 6 inside a Future[Int]

Fluent

Documentation

Advantages

• Less verbose syntax:
  • StringWhen, RegexWhen, etc is just when.
  • Returning, ReturningWithRegex, etc is just returning.
  • Less commas and parenthesis.
• Most errors will be caught at compile time.
• Easy to add expect blocks/whens/actions based on a condition.
• Easy to refactor the creation of expects.
• Can be called from Java easily.

Disadvantages

• Some overhead since the fluent expect is just a builder for a core expect.
• Mutable - the fluent expect has to maintain a state of the objects that have been built.
• IDE's will easily mess the custom indentation.

Example

import work.martins.simon.fluent._
import scala.concurrent.ExecutionContext.Implicits.global

val e = new Expect("bc -i", defaultValue = 5) {
  expect
    .when("For details type `warranty'.")
      .sendln("1 + 2")
  expect
    .when("""\n(\d+)\n""".r)
      .sendln { m =>
        val previousAnswer = m.group(1)
        println(s"Got $previousAnswer")
        s"$previousAnswer + 3"
      }
  //This is a shortcut. It works just like the previous expect block.
  expect("""\n(\d+)\n""".r)
    .returning(_.group(1).toInt)
}
e.run() //Returns 6 inside a Future[Int]

DSL

Documentation

Advantages

• Code will be indented in blocks so IDE's won't mess the indentation.
• Syntax more close to the TCL expect.
• Easy to add expect blocks/whens/actions based on a condition.
• Easy to refactor the creation of expects.

Disadvantages

• Most errors will only be caught at runtime as opposed to compile time.
• More overhead than the fluent expect since it's just a wrapper arround fluent expect.
• Mutable - it uses a fluent expect as the backing expect and a mutable stack to keep track of the current context.

Example

import work.martins.simon.dsl._
import scala.concurrent.ExecutionContext.Implicits.global

val e = new Expect("bc -i", defaultValue = 5) {
  expect {
    when("For details type `warranty'.") {
      sendln("1 + 2")
    }
  }
  expect {
    when("""\n(\d+)\n""".r) {
      sendln { m =>
        val previousAnswer = m.group(1)
        println(s"Got $previousAnswer")
        s"$previousAnswer + 3"
      }
    }
  }
  //This is a shortcut. It works just like the previous expect block.
  expect("""\n(\d+)\n""".r) {
    returning(_.group(1).toInt)
  }
}
e.run() //Returns 6 inside a Future[Int]

License

Scala Expect is open source and available under the MIT license.