index.md

Intent is a test framework for Dotty (which is expected to become Scala 3 in year 2020).

Intent is designed to give you clear and concise tests by focusing on:

• Low cermony test code
• Uniform test declaration
• Futures and async testing
• Arranging test state
• Fast to run tests

Why a new test framework?

The idea of a new test framework was born out of both the frustration and inspiration of using existing frameworks. Having written tens of thousands of tests using a variety of languages and frameworks there are a few challenges that keep surfacing.

Structure - when you have thousands of tests it is important that the ceremony to add a new test is as low as possible. If a test belongs to the same functionality as other tests, these tests should stay together.

Intent's goal is that it should be possible to express a simple test in a single line and still have that line clearly express the intention of the test.

State, most tests are not stateless, instead they require setup code in order to get to the state of interest for a particular test. Setting up this state is often verbose, heavily imperative and worst of all repeated over and over again.

Intent's goal is to make the dependency on state obvious for each test, and to allow state transformation in a hierarchical structure.

Expectation, when using fluent and nested matchers we feel that it increases the cognitive load when writing the tests. You need to know each and every one of the qualified behaviours until you get to the one actually performing the assert. Having too simple matchers on the other hand results in more test code, and therefore introduce more noise to achieve the same expectation.

Intent's goal is to make assertions easy to find and use while also supporting the most common expectations.

Intent is built, not to circumvent these challenges, but to put them front and center. As we believe these three attributes are the most significant for achieving good quality test they should be the foundation of a test framework.

It deserves to be said that Intent pays homage to in particular two test frameworks that has inspired us greatly:

• Jasmine, supporting nested tests and the format of the expect / matchers
• ScalaTest, FreeSpec style and the use of test fixtures

Using Dotty and the new features are also a motivator, having fun and experimenting is always important.

Let us see how a test suite looks like for intent:

class StatefulTest extends TestSuite with State[Cart]:
  "an empty cart" using Cart() to :
    "with two items" using (_.add(CartItem("beach-chair", 2))) to :
      "and another three items" using (_.add(CartItem("sunscreen", 3))) to :
        "contains 5 items" in :
          cart => expect(cart.totalQuantity).toEqual(5)

case class CartItem(artNo: String, qty: Int)
case class Cart(items: Seq[CartItem] = Seq.empty):
  def add(item: CartItem): Cart = copy(items = items :+ item)
  def totalQuantity = items.map(_.qty).sum

Want to know more? Continue with getting started