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Specification

This style is inspired by test frameworks like Jasmine and RSpec.

object CalculatorSpec: Spek({
    describe("A calculator") {
        val calculator by memoized { Calculator() }

        describe("addition") {
            it("returns the sum of its arguments") {
                assertThat(3, calculator.add(1, 2))
            }
        }
    }
})

Concepts

Suites

Defined by either calling describe or context, they are used to group related specs.

Specs

Defined by calling it, is the place where you usually place your assertions/checks.

Skipping

describe, context and it can be prefixed with an x which will tell Spek to skip them during execution.

Aliases

This style also provides aliases to the built-in fixtures.

  • before and after is equivalent to beforeGroup and afterGroup, respectively.
  • beforeEach and afterEach is equivalent to beforeEachTest and afterEachTest, respectively.

Best practices

Validating a side-effect

describe should be use to describe the action and an it to check the expected side-effect.

val set by memoized { mutableSetOf<String>() }

describe("adding an item") {
    beforeEachTest {
        set.add("item")
    }

    it("should contain item") {
        assertEquals("item", set[0])
    }
}

Use multiple its if you need to check several side-effects.

val set by memoized { mutableSetOf<String>() }

describe("adding an item") {
    beforeEachTest {
        set.add("item")
    }

    it("should contain item") {
        assertEquals("item", set[0])
    }

    it("should have a size > 0") {
        assertTrue(set.size() > 0)
    }
}

Validating a return value

Like the previous section, use describe to describe the action, it check the expected value and a lateinit variable to store the result of the action.

describe("adding 1 + 2") {
    lateinit var result: Int
    beforeEachTest {
        result = 1 + 2
    }

    it("result should be 3") {
        assertEquals(result, 3)
    }
}