Testing Groovy and Java projects - Making Java Groovy - page 212

These tests use the when / then blocks, which are used as a stimulus/response pair. Any
code can be added to the when block, but the then block must consist of Boolean ex-
pressions, as with expect . The expressions are evaluated automatically, using the Groovy
Truth. This means that non-null references, non-empty strings, and non-zero numbers all
evaluate to true.
The charAt methodin String throwsanexceptionifitsargumentisnegativeorbeyond
the end of the string. The previous two tests show both conditions, using the thrown()
and notThrown() methods. The thrown method can return the exception if you want
to process it further, using one of two variations in syntax
Exception e = thrown()
or
e = thrown(Exception)
where the Exception can be any specific exception class.
Consider the following test, which also introduces the extremely useful old method.
Listing 6.27. Another spec, illustrating the old method
class QuoteSpec extends Specification {
String quote = """I am endeavoring, ma'am, to construct a
mnemonic memory circuit, using stone knives and bear skins."""
List<String> strings
def setup() { strings = quote. tokenize (" ,.") }
def "test string has 16 words"() {
expect: strings.size() == 16
}
def "adding a word increases total by 1"() {
when: strings << 'Fascinating'
then: strings.size() == old(strings.size()) + 1
}
}