Using Mockito to mock a local variable of a method
functional-testing, java, mocking, mockito
Solution
You cannot mock a local variable. What you could do, however, is extract its creation to a `protected` method and `spy` it:
public class A {
public void methodOne(int argument) {
//some operations
methodTwo(int argument);
//some operations
}
private void methodTwo(int argument) {
DateTime dateTime = createDateTime();
//use dateTime to perform some operations
}
protected DateTime createDateTime() {
return new DateTime();
}
}
public class ATest {
@Test
public void testMethodOne() {
DateTime dt = new DateTime (/* some known parameters... */);
A a = Mockito.spy(new A());
doReturn(dt).when(a).createDateTime();
int arg = 0; // Or some meaningful value...
a.methodOne(arg);
// assert the result
}
Problem
I have a class `A` that needs to the tested. The following is the definition of `A`: ``` public class A { public void methodOne(int argument) { //some operations methodTwo(int argument); //some operations } private void methodTwo(int argument) { DateTime dateTime = new DateTime(); //use dateTime to perform some operations } } ``` And based on the `dateTime` value some data is to be manipulated, retrieved from the database. For this database, the values are persisted via a JSON file. This complicates things. What I need is to set the `dateTime` to some specific date while it is being tested. Is there a way I can mock a local variable's value using mockito?