Mockito mock creation inside mock creation - mockito

Question

The error I get is org.mockito.exceptions.misusing.UnfinishedStubbingException, with one of the possible reasons "you are stubbing the behaviour of another mock inside before 'thenReturn' instruction if completed".
val mockHttpHandlerContext = mock<HttpHandlerContext>().let {
whenever(it.request).thenReturn(mock<HttpRequest>().let {
whenever(it.queryParameters).thenReturn(mapOf(
"itype" to listOf("msisdn"),
"uid" to listOf(inputMsisdn)
))
it
})
whenever(it.scope()).thenReturn(ProcessingScope.of(Timings("test", 1000L)))
it
}
Is the only solution to get rid of nested mock creation? It would really make code harder to understand, maybe there is a known workaround?
The code snippet is Kotlin.

Answer 1

Judging by the naming, I assume you're using nhaarman/Mockito-Kotlin?
Mockito is stateful, you must create mocks sequentially, but there are some ways of flipping the order of evaluation. For example,
val mockHttpHandlerContext2 = mock<HttpHandlerContext>() {
mock<HttpRequest>() {
on { queryParameters }.thenReturn(mapOf(
"itype" to listOf("msisdn"),
"uid" to listOf(inputMsisdn)
))
}.let { on { request }.thenReturn(it) }
on { scope() }.thenReturn(ProcessingScope.of(Timings("test", 1000L)))
}
I'm taking advantage of the mock() overload with a KStubbing<T> receiver, but the important bit is creating the inner mock first before using .let to set it on the stub.
Another option would be to use .thenAnswer to defer creation of the inner mock until the time when stubbed method is called.
val mockHttpHandlerContext = mock<HttpHandlerContext>() {
on { request }.thenAnswer {
mock<HttpRequest>() {
on { queryParameters }.thenReturn(mapOf(
"itype" to listOf("msisdn"),
"uid" to listOf(inputMsisdn)
))
}
}
on { scope() }.thenReturn((ProcessingScope.of(Timings("test", 1000L)))
}
Note that this will create a new mock every time the stubbed method is called. It might not be desirable in some situations, such as if you want to perform verification on the inner mock.