Mocking data classes by defaulting properties

Hi, is there a way to mock data classes by calling their constructor with all values mocked?

I have data classes with tens of values and I have to instantiate them with some values even though I don’t need all the values for my particular test. I don’t want to specify default values in their constructors since default values are only for tests.

For example. if I have the following data class with many properties:

data class Foo(
        val a: String,
        val b: Int,
        val c: Boolean,
        val d: Long,
        // ... more properties here
)

I would like this test to work:

// call Foo constructor by mocking all arguments to defaults like empty string, 0 or false
val bar = spyk<Foo>().copy(a = "bar", c = true)
assertEquals("bar", bar.a)
assertEquals(true, bar.c)
assertEquals(bar, spyk<Foo>().copy(a = "bar", c = true))  // data class equals used

Is there a way to do something like this in mockk or would it be possible to implement it? I could look into it if you point me in the right direction.

[headsvk]

@Raibaz actually mocking a data class is not a good idea as it breaks the data class contract, copy/equals/toString doesn’t work as expected, so using such mocked class would cause issues in tested code.

[Raibaz]

In that case, you can still declare a val foo: Foo = mockk().

You can then either have your mock provide default answers by passing relaxed = true, or specifying the answers you want on your own like

every { foo.a } returns "a value"