Test Groovy class that uses System.console()

Question

I have a groovy script that asks some questions from the user via a java.io.console object using the readline method. In addition, I use it to ask for a password (for setting up HTTPS). How might I use Spock to Unit Test this code? Currently it complains that the object is a Java final object and can not be tested. Obviously, I'm not the first one trying this, so thought I would ask.

A sketch of the code would look something like:

class MyClass {

   def cons

   MyClass() {
     cons = System.console()
   }

   def getInput = { prompt, defValue ->
     def input = (cons.readLine(prompt).trim()?:defValue)?.toString()
     def inputTest = input?.toLowerCase()
     input
   }
}

I would like Unit Tests to test that some mock response can be returned and that the default value can be returned. Note: this is simplified so I can figure out how to do the Unit Tests, there is more code in the getInput method that needs to be tested too, but once I clear this hurdle that should be no problem.

EDITED PER ANSWER BY akhikhl Following the suggestion, I made a simple interface:

interface TestConsole {
    String readLine(String fmt, Object ... args)
    String readLine()
    char[] readPassword(String fmt, Object ... args)
    char[] readPassword()
}

Then I tried a test like this:

def "Verify get input method mocking works"() {

    def consoleMock = GroovyMock(TestConsole)
    1 * consoleMock.readLine(_) >> 'validResponse'

    inputMethods = new MyClass()
    inputMethods.cons = consoleMock

    when:
    def testResult = inputMethods.getInput('testPrompt', 'testDefaultValue')
    then:
    testResult == 'validResponse'
}

I opted to not alter the constructor as I don't like having to alter my actual code just to test it. Fortunately, Groovy let me define the console with just a 'def' so what I did worked fine.

The problem is that the above does not work!!! I can't resist - this is NOT LOGICAL! Spock gets 'Lost' in GroovyMockMetaClass somewhere. If I change one line in the code and one line in the test it works.

Code change:

From:
    def input = (cons.readLine(prompt).trim()?:defValue)?.toString()
To: (add the null param)
    def input = (cons.readLine(prompt, null).trim()?:defValue)?.toString()

Test change:

From:
    1 * consoleMock.readLine(_) >> 'validResponse'
To: (again, add a null param)
    1 * consoleMock.readLine(_, null) >> 'validResponse'

Then the test finally works. Is this a bug in Spock or am I just out in left field? I don't mind needing to do whatever might be required in the test harness, but having to modify the code to make this work is really, really bad.

Test Groovy class that uses System.console()

1 Answers