mockExtensionFun

Creates a thread-local mock for the static methods of the class that contains this top-level extension function.

Top-level Kotlin extension functions compile to static methods in a *Kt class. This helper simplifies creating a MockedStatic for them.

Usage:

fun String.isHello(): Boolean = this == "Hello"

mockExtensionFun(String::isHello).use {
    whenever("test".isHello()).thenReturn(true)
    println("test".isHello()) // "true"
}

When using matchers, all arguments including the receiver must use matchers:

fun String.hasPrefix(prefix: String): Boolean = this.startsWith(prefix)

mockExtensionFun(String::hasPrefix).use {
    whenever(any<String>().hasPrefix(eq("foo"))).thenReturn(true)
    println("bar".hasPrefix("foo")) // "true"
}

Note: member extension functions (extension functions declared inside a class) do not need this helper. They can be mocked by creating a regular mock of the containing class.

Parameters

See also