Design and Architectural Principles - Java 8 Lambdas - page 135

specification . specifyBehaviour ( expect );
Runner . current . recordSuccess ( suite , description );
} catch catch ( AssertionError cause ) {

Runner . current . recordFailure ( suite , description , cause );
} catch catch ( Throwable cause ) {

Runner . current . recordError ( suite , description , cause );

}

}

When our specifications want to describe an actual expectation, they use the expect.that
clause. This means that our Expect class needs to have a method called that for users to
call, shown in Example 8-33 . This wraps up the object that gets passed in and can then ex-
pose fluent methods such as isEqualTo that throw the appropriate assertions if there's a spe-
cification failure.

Example 8-33. The start of the fluent expect chain
public

public final final class class Expect Expect {

public public BoundExpectation that ( Object value ) {

return

return new new BoundExpectation ( value );

}

// Rest of class omitted

You may have noticed one more detail that I've so far ignored and that has nothing to do
with lambda expressions. Our StackSpec class didn't have any methods directly implemen-
ted on it, and I wrote the code inside. I've been a bit sneaky here and used double braces at
the beginning and end of the class definition:

public public class class StackSpec StackSpec {{

...

}}

These start an anonymous constructor that lets us execute an arbitrary block of Java code, so
it's really just like writing out the constructor in full, but with a bit less boilerplate. I could
have written the following instead:

public public class class StackSpec StackSpec {

public public StackSpec () {

...