Helper for Mockito Scala sugar with idiomatic stubbing. Java users are encouraged to use org.mockito.Mockito directly.

Note that the Specs2 smartMock[] or mock[].smart is the default behavior for Mockito Scala.

Usage

This trait uses org.mockito.IdiomaticMockito which is heavily influenced by ScalaTest Matchers.

To use, mix in the com.twitter.util.mock.Mockito trait where desired.

Create a new mock

trait Foo {
  def bar: String
  def bar(v: Int): Int
}

 class MyTest extends AnyFunSuite with Mockito {
    val aMock = mock[Foo]
 }

Expect behavior

// "when" equivalents
aMock.bar returns "mocked!"
aMock.bar returns "mocked!" andThen "mocked again!"
aMock.bar shouldCall realMethod
aMock.bar.shouldThrow[IllegalArgumentException]
aMock.bar throws new IllegalArgumentException
aMock.bar answers "mocked!"
aMock.bar(*) answers ((i: Int) => i * 10)

// "do-when" equivalents
"mocked!" willBe returned by aMock.bar
"mocked!" willBe answered by aMock.bar
((i: Int) => i * 10) willBe answered by aMock.bar(*)
theRealMethod willBe called by aMock.bar
new IllegalArgumentException willBe thrown by aMock.bar
aMock.bar.doesNothing() // doNothing().when(aMock).bar

// verifications
aMock wasNever called          // verifyZeroInteractions(aMock)
aMock.bar was called
aMock.bar(*) was called        // '*' is shorthand for 'any()' or 'any[T]'
aMock.bar(any[Int]) was called // same as above but with typed input matcher

aMock.bar wasCalled onlyHere
aMock.bar wasNever called

aMock.bar wasCalled twice
aMock.bar wasCalled 2.times

aMock.bar wasCalled fourTimes
aMock.bar wasCalled 4.times

aMock.bar wasCalled atLeastFiveTimes
aMock.bar wasCalled atLeast(fiveTimes)
aMock.bar wasCalled atLeast(5.times)

aMock.bar wasCalled atMostSixTimes
aMock.bar wasCalled atMost(sixTimes)
aMock.bar wasCalled atMost(6.times)

aMock.bar wasCalled (atLeastSixTimes within 2.seconds) // verify(aMock, timeout(2000).atLeast(6)).bar

aMock wasNever calledAgain // verifyNoMoreInteractions(aMock)

InOrder(mock1, mock2) { implicit order =>
  mock2.someMethod() was called
  mock1.anotherMethod() was called
}

Note the 'dead code' warning that can happen when using 'any' or '*' matchers.

Mixing and matching matchers

Using the idiomatic syntax also allows for mixing argument matchers with real values. E.g., you are no longer forced to use argument matchers for all parameters as soon as you use one. E.g.,

trait Foo {
  def bar(v: Int, v2: Int, v3: Int = 42): Int
}

class MyTest extends AnyFunSuite with Mockito {
  val aMock = mock[Foo]

  aMock.bar(1, 2) returns "mocked!"
  aMock.bar(1, *) returns "mocked!"
  aMock.bar(1, any[Int]) returns "mocked!"
  aMock.bar(*, *) returns "mocked!"
  aMock.bar(any[Int], any[Int]) returns "mocked!"
  aMock.bar(*, *, 3) returns "mocked!"
  aMock.bar(any[Int], any[Int], 3) returns "mocked!"

  "mocked!" willBe returned by aMock.bar(1, 2)
  "mocked!" willBe returned by aMock.bar(1, *)
  "mocked!" willBe returned by aMock.bar(1, any[Int])
  "mocked!" willBe returned by aMock.bar(*, *)
  "mocked!" willBe returned by aMock.bar(any[Int], any[Int])
  "mocked!" willBe returned by aMock.bar(*, *, 3)
  "mocked!" willBe returned by aMock.bar(any[Int], any[Int], 3)

  aMock.bar(1, 2) was called
  aMock.bar(1, *) was called
  aMock.bar(1, any[Int]) was called
  aMock.bar(*, *) was called
  aMock.bar(any[Int], any[Int]) was called
  aMock.bar(*, *, 3) was called
  aMock.bar(any[Int], any[Int], 3) was called
}

See Mix-and-Match for more information including a caveat around curried functions with default arguments.

Numeric Matchers

Numeric comparisons are possible for argument matching, e.g.,

aMock.method(5)

aMock.method(n > 4.99) was called
aMock.method(n >= 5) was called
aMock.method(n < 5.1) was called
aMock.method(n <= 5) was called

See Numeric Matchers.

Vargargs

Most matches will deal with varargs out of the box, just note when using the 'eqTo' matcher to apply it to all the arguments as one (not individually).

See Varargs.

More Information

See the IdiomaticMockito documentation for more specific information and the Mockito Scala Getting Started documentation for general information.