Kotlin 测试，如何使用DescribeSpec 测试风格运行BeforeEach

Question

我正在尝试写 KotlinTest在 JUnit5 上运行的测试，带有 Describe Spec style .

当我需要为某些测试初始化​​相同的变量时，@BeforeEach 在DescribeSpec 中不起作用。

如何在每次测试前初始化数据？

class BlockchainUT : DescribeSpec({

    var blockchain = Blockchain()

    @BeforeEach
    fun beforeEach() {
        blockchain = Blockchain()
        blockchain.addBlock(listOf("foo1", "bar1"))
        blockchain.addBlock(listOf("foo2", "bar2"))
        blockchain.addBlock(listOf("foo3", "bar3"))
    }

    describe("isValidChain()") {

        context("when the chain does not start with the genesis block") {

            blockchain.chain[0] = Block(
                    System.currentTimeMillis(),
                    "---",
                    "xxx",
                    listOf("foo", "bar"))

            it("returns false") {
                Blockchain.isValid(blockchain) shouldBe false
            }
        }

        context("when the chain starts with the genesis block and has multiple blocks") {

            context("and a lastHash reference has changed returns false") {
                blockchain.chain[2] = Block(
                        blockchain.chain[2].timestamp,
                        "broken-lastHash",
                        blockchain.chain[2].hash,
                        blockchain.chain[2].data)
                it("returns false") {
                    Blockchain.isValid(blockchain) shouldBe false
                }
            }

            context("and the chain contains a block with an invalid field") {
                blockchain.chain[2] = Block(
                        blockchain.chain[2].timestamp,
                        blockchain.chain[2].lastHash,
                        blockchain.chain[2].hash,
                        listOf("some-bad-and-evil-data"))
                it("returns false") {
                    Blockchain.isValid(blockchain) shouldBe false
                }
            }
        }

    }
})

Answer 1

在新版本的 KotlinTest 3.3 上有新的 Listeners定义 beforeTest、afterTest、beforeSpec 等。

在这种情况下，可能的解决方案应该是:

class BlockchainUT : DescribeSpec(), TestListener {

    var blockchain = Blockchain()

    override fun beforeTest(describe: TestCase): Unit {
        blockchain = Blockchain()
        blockchain.addBlock(listOf("foo1", "bar1"))
        blockchain.addBlock(listOf("foo2", "bar2"))
        blockchain.addBlock(listOf("foo3", "bar3"))
    }

    init {
        describe("isValidChain()") {

            context("when the chain starts with the genesis block and has multiple blocks") {

                context("and a lastHash reference has changed returns false") {

                    blockchain.chain[2] = Block(
                            blockchain.chain[2].timestamp,
                            "broken-lastHash",
                            blockchain.chain[2].hash,
                            blockchain.chain[2].data)

                    it("returns false") {
                        Blockchain.isValid(blockchain) shouldBe false
                    }
                }

                context("and the chain contains a block with an invalid field") {

                    blockchain.chain[2] = Block(
                            blockchain.chain[2].timestamp,
                            blockchain.chain[2].lastHash,
                            blockchain.chain[2].hash,
                            listOf("some-bad-and-evil-data"))

                    it("returns false") {
                        Blockchain.isValid(blockchain) shouldBe false
                    }
                }

                context("and the chain does not contain any invalid blocks") {

                    it("returns true") {
                        Blockchain.isValid(blockchain) shouldBe true
                    }
                }
            }
        }
    }
}

也可以使用新的 Isolation Modes 来解决，将隔离模式定义为InstancePerLeaf。来自 io.kotlintest.IsolationMode javadoc:

A new instance of the [Spec] class is instantiated for every
[TestCase] - both containers and leaf tests - and they are
executed once the previous test has completed.
For example, in the following test plan:
"this test" {
  println("a")
  "nested test" {
    println("b")
  }
  "nested test 2" {
    println("c")
  }
}
The output will be:
a
a
b
a
c

最后移动您想要为每个 [TestCase] 重复的代码

class BlockchainUT : DescribeSpec(){

    override fun isolationMode() = IsolationMode.InstancePerTest

        describe("isValidChain()") {

            context("when the chain starts with the genesis block and has multiple blocks") {

                var blockchain = Blockchain()
                blockchain.addBlock(listOf("foo1", "bar1"))
                blockchain.addBlock(listOf("foo2", "bar2"))
                blockchain.addBlock(listOf("foo3", "bar3"))

                context("and a lastHash reference has changed returns false") {

                    blockchain.chain[2] = Block(
                            blockchain.chain[2].timestamp,
                            "broken-lastHash",
                            blockchain.chain[2].hash,
                            blockchain.chain[2].data)

                    it("returns false") {
                        Blockchain.isValid(blockchain) shouldBe false
                    }
                }

                context("and the chain contains a block with an invalid field") {

                    blockchain.chain[2] = Block(
                            blockchain.chain[2].timestamp,
                            blockchain.chain[2].lastHash,
                            blockchain.chain[2].hash,
                            listOf("some-bad-and-evil-data"))

                    it("returns false") {
                        Blockchain.isValid(blockchain) shouldBe false
                    }
                }

                context("and the chain does not contain any invalid blocks") {

                    it("returns true") {
                        Blockchain.isValid(blockchain) shouldBe true
                    }
                }
            }
        }
    }
}