I'm having some difficulty setting up unit tests f...

# clikt

[Carlton Whitehead]

I'm having some difficulty setting up unit tests for my subcommands which use requireObject() to pull in state from parent commands. Ideally, I'd like to install these through the context builder. Example code in thread.

[Carlton Whitehead]

class Subcommand : CliktCommand() {

    private val environment: Environment by requireObject()
    
    override fun run() {
        echo(environment.value)
    }
}

class SubcommandTest : CliktCommand() {
    
    lateinit var subcommand: Subcommand
    
    lateinit var testConsole: StringBufferConsole
    
    @BeforeEach
    fun beforeEach() {
        testConsole = StringBufferConsole()
        subcommand = Subcommand()
            .context {
                console = testConsole
                obj = Environment(value = "test")
                // but there is no `obj` available in Context.Builder
            }
    }
    
    @Test
    fun `It should echo environment value`() {
        subcommand.parse(emptyArray())
        
        assertThat(testConsole.output).contains("test")
    }
}

I tried setting it through subcommand.currentContext.obj during beforeEach(), but accessing the context prior to parse is not allowed. For the time being, I've resorted to adding constructor parameters to each of my subcommands to allow the unit tests to override the environment.

class SubcommandTest(forceEnvironment: Environment? = null) : CliktCommand() {
    private val environment: Environment by requireObject()
    
    override fun run() {
        val useEnvironment = forceEnvironment ?: environment
        echo(useEnvironment.value)
    }
}

I'm not too fond of this approach because it adds complexity to main code simply for test concerns. It feels like a missing feature that there isn't a way to pass an obj value into the context from the context builder. Have I missed something here?

Is there a better way I should approach this instead?

[AJ Alt]

Given that your class is expected to be a subcommand, I would suggest testing it as one:

class Parent : CliktCommand() {
    override fun run() {
        currentContext.obj = Environment("test")
    }
}

@Test
fun `It should echo environment value`() {
    Parent().context { console = testConsole }
        .subcommands(Subcommand())
        .parse(emptyArray())

    assertThat(testConsole.output).contains("test")
}

[AJ Alt]

Although adding an obj setter to the context builder also seems like a reasonable feature.

[Carlton Whitehead]

That seems like a practical compromise between completely isolating the unit under test (I have quite a preference towards this), the coupling that exists due to the command/subcommand relationship, and the limitation of the framework. In the case of an app with multiple nesting levels of commands which each contribute obj values, I could see this being a preferred approach.

Another option I've since tried is a singleton model. Write the value in the root command, and then read the value in subcommands. This leads to quite a lot of constructor boilerplate throughout an app with many subcommands but otherwise works out pretty nicely for my use case.

My preference remains for there to be an obj available in the Context.Builder. I'll send you a PR adding support for that.

[Carlton Whitehead]

https://github.com/ajalt/clikt/pull/315