Groovy Spock File test - unit-testing

Question

I'm about to start learning spock and I'm trying some basic stuff.
I want to check File's: exist() and getText() functionality
So I wrote the following test:
class MyTestSpec extends Specification {
def "test file"() {
given:
def mockFile = Mock(File,constructorArgs :["./doesNotExist.txt"])
mockFile.exists() >> true
mockFile.getText() >> "sampleText"
when:
def res = ""
if(mockFile.exists()) {
res = mockFile.getText()
}
then:
"sampleText" == res
1 * mockFile.exists()
1 * mockFile.getText()
}
}
This fails on:
Too few invocations for:
1 * mockFile.getText() (0 invocations)
Unmatched invocations (ordered by similarity):
None
When I comment the 'verifications' in 'then' block, I get:
java.lang.NullPointerException at
java.io.FileInputStream.(FileInputStream.java:138) at
groovy.util.CharsetToolkit.(CharsetToolkit.java:69) at
MyTestSpec.Test Existing Resource(MyTestSpec.groovy:83)
So my question is: How Exactly I can organize my test? Why does it assume that getText should not be called?
I'm using groovy 2.4 and spock 1.0

Answer 1

The solution will be:
#Grab('org.spockframework:spock-core:0.7-groovy-2.0')
#Grab('cglib:cglib:3.1')
#Grab('org.ow2.asm:asm-all:5.0.3')
import spock.lang.*
class MyTestSpec extends Specification {
def "test file"() {
given:
def mockFile = GroovyMock(File, constructorArgs :["./doesNotExist.txt"])
when:
def res = ""
if(mockFile.exists()) {
res = mockFile.getText()
}
then:
"sampleText" == res
1 * mockFile.exists() >> true
1 * mockFile.getText() >> "sampleText"
}
}
On of the problems is creating a mock. Because of a dynamic nature of groovy some functionality - e.g. getText() method for File class - is added at runtime. It requires mocks to be constructed in a different way. Have a look at spock mock implementation enum and extract:
An implementation specifically targeting Groovy callers. Supports mocking of dynamic methods, constructors, static methods, and "magic" mocking of all objects of a particular type.
The second problem is defining mock behavior and verifying the interactions. When you both mock and stub it must happen in the same interaction (here, in then block), here is he relevant part of the docs.