Aha. If I have top-level

foo: (File)->Long

I want to mock, and top-level (same file)

caller: (foo: (File)->Long)->Int

that I do not want to mock, then that file needs

@file:JvmName("FooKt") ; package <http://path.to|path.to>

up top, and then in the test:

with(::caller) {
            mockkStatic("path.to.FooKt")
            every { foo(any()) } returns 0L

            this(::foo)

            verify { foo(File("/path/to/thing") }
        }

@JvmName

is not neccessary if your file is called

Foo.kt

since kotlin compiler will generate a class called

xKt

for a file named

x.kt

.

@Karolisthe MockK docs say otherwise for top-level functions: https://blog.kotlin-academy.com/mocking-is-not-rocket-science-mockk-advanced-features-42277e5983b5 (under the heading for Top-Level Functions:

To know exactly where such function as [top-level function]

lowercase

will land you need to check actual class files produced by the build.

Sometimes names are fancy. For example:

mockkStatic(“kotlin.io.FilesKt__UtilsKt”)

every { File(“abc”).endsWith(any<String>()) } returns true

In Kotlin there is a special directive to guide compiler what file to put such top-level functions. It is called

@file:JvmName

[snip]

TIL, thanks! Didn't know about those fancy names.

No problem. I’m just lucky I found those docs. I got it working, but hit a wall, refactored, then realized I could have spied instead of mocked. Oh well, you live, you learn 🙂