Java Reference
In-Depth Information
The
out
property of the binding is assigned to a
PrintWriter
wrapped around a
StringWriter
, so that when the
println
method in the script is executed, the output
goes to the writer instead of the console. Then, after executing the script using the shell, I
can check that the proper statement was printed by accessing the writer and trimming its
output.
Normally a binding is used to pass input variables into a script. Here's a slight variation on
the previous example, using a
name
variable.
Listing 6.10. A script with a binding variable
package mjg
println "Hello, $name!"
Again, the only real difference here is that the
print
statement uses a
name
variable that
is not declared inside the script. That means it can be passed in from outside, as shown in
the following test.
Listing 6.11. Setting a binding variable to test a script
@Test
void testHelloName() {
Binding binding = new Binding()
binding.name = 'Dolly'
def content = new StringWriter()
binding.out = new PrintWriter(content)
GroovyShell shell = new GroovyShell(binding)
shell.evaluate(new File('src/main/groovy/mjg/hello_name.groovy'))
assert
"Hello, Dolly!" == content.toString().trim()
}
The
name
variable is set to Dolly, and the result is confirmed as before.
6.2.1. Useful subclasses of GroovyTestCase: GroovyShellTestCase
The combination of script and binding is sufficiently common that the Groovy API now
includes the class
groovy.util.GroovyShellTestCase
. This is a subclass of
GroovyTestCase
that instantiates a
GroovyShell
inside the
setUp
method. The
shell is provided as a protected attribute, but the class also includes a
withBinding
method that takes a
Map
of parameters and a closure to execute. The following listing
shows tests for the Groovy scripts in this section.
