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

Question

我正在尝试编写在JUnit5上运行的KotlinTest测试，使用描述规范样式。

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。

如何在每次测试之前初始化数据？

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 KotlinTest 3.3 上，有新的侦听器来定义beforeTest、afterTest、beforeSpec等。

在这种情况下，一个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
                    }
                }
            }
        }
    }
}

也可以使用新的隔离模式来解决，将隔离模式定义为InstancePerLeaf。从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

3. 最后移动要为每个 [测试用例] 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
                    }
                }
            }
        }
    }
}