trait OptionValues extends AnyRef
Trait that provides an implicit conversion that adds a value
method
to Option
, which will return the value of the option if it is defined,
or throw TestFailedException
if not.
This construct allows you to express in one statement that an option should be defined and that its value should meet some expectation. Here's an example:
opt.value should be > 9
Or, using an assertion instead of a matcher expression:
assert(opt.value > 9)
Were you to simply invoke get
on the Option
,
if the option wasn't defined, it would throw a NoSuchElementException
:
val opt: Option[Int] = None
opt.get should be > 9 // opt.get throws NoSuchElementException
The NoSuchElementException
would cause the test to fail, but without providing a stack depth pointing
to the failing line of test code. This stack depth, provided by TestFailedException
(and a
few other ScalaTest exceptions), makes it quicker for
users to navigate to the cause of the failure. Without OptionValues
, to get
a stack depth exception you would need to make two statements, like this:
val opt: Option[Int] = None
opt should be ('defined) // throws TestFailedException opt.get should be > 9
The OptionValues
trait allows you to state that more concisely:
val opt: Option[Int] = None
opt.value should be > 9 // opt.value throws TestFailedException
- Source
- OptionValues.scala
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Implicit conversion that adds a
value
method toOption
.Implicit conversion that adds a
value
method toOption
.- opt
the
Option
on which to add thevalue
method
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