Is there a way to bind properties from one instance of a class to the properties of an instance of another class (the common fields between the two). See the example below:
class One {
String foo
String bar
}
class Two {
String foo
String bar
String baz
}
def one = new One(foo:'one-foo', bar:'one-bar')
def two = new Two()
two.properties = one.properties
assert "one-foo" == two.foo
assert "one-bar" == two.bar
assert !two.baz
The result is an error: Cannot set readonly property: properties for class: Two
I would choose InvokerHelper.setProperties as I suggesed here.
use(InvokerHelper) {
two.setProperties(one.properties)
}
The problem is that for every object, .properties includes two built-in Groovy-defined properties, these are the metaClass and class. What you want to do is only set the user-defined properties. You can easily do this using code such as that shown below:
class One {
String foo
String bar
}
class Two {
String foo
String bar
String baz
}
def one = new One(foo:'one-foo', bar:'one-bar')
// You'll probably want to define a helper method that does the following 3 lines for any Groovy object
def propsMap = one.properties
propsMap.remove('metaClass')
propsMap.remove('class')
def two = new Two(propsMap)
assert "one-foo" == two.foo
assert "one-bar" == two.bar
assert !two.baz
Related
When I'm trying to use snakeyaml to dump out Yaml out of Groovy interpolated strings, it ends up printing a class name instead.
For example:
#Grab(group='org.yaml', module='snakeyaml', version='1.16')
import org.yaml.snakeyaml.Yaml
Yaml yaml = new Yaml();
def a = "a"
def list = ["$a"]
def s = yaml.dump(list)
Prints:
- !!org.codehaus.groovy.runtime.GStringImpl
metaClass: !!groovy.lang.MetaClassImpl {}
I'm guessing it has something to do with the fact that GStrings get transformed to Strings when they used and I suspect snakeyaml uses some sort of introspection to determine the class of the object.
Is there a better solution than calling toString() on all GStrings?
Try to create a new Representer :
public class GroovyRepresenter extends Representer {
public GroovyRepresenter() {
this.representers.put(GString.class, new StringRepresenter());
}
}
Yaml yaml = new Yaml(new GroovyRepresenter())
...
You could add type info to your variables
Yaml yaml = new Yaml();
def a = "a"
String aStr = "$a"
def list = [aStr]
def s = yaml.dump(list)
I'm writing Groovy scripts that are pasted into a web-based system to be run. There is a
class available to scripts run in this environment which I'll call BrokenClass. It has a
bug where it will only accept a string literal as its first parameter, but not a variable
with a string in it. So, this will work (it returns a list):
BrokenClass.reflist('something', 'name')
However, if I try to use a variable as the first parameter I get an error:
list_name = 'something'
BrokenClass.reflist(list_name, 'name')
This produces the message Metadata RefList[something] cannot be accessed.
I don't have any control over BrokenClass (aside from filing a bug on it). I tried to work
around the problem with something like this:
list_name = "foo"
list_call = "BrokenClass.reflist(${list_name}, 'name')"
list_values = Eval.me(list_call)
However, that produces an error:
groovy.lang.MissingPropertyException: No such property: BrokenClass for class: Script1
I tried adding an import to my string, but then I get unable to resolve class BrokenClass.
Is there a way to use BrokenClass inside the eval'd string? Or some other way I haven't
considered to work around the bug in BrokenClass.reflist? A really long switch block
is out, because the possible list names change.
The method signature for BrokenClass.reflist is:
public static List<Object> reflist(String reflistName, String field);
I have a suspicion that BrokenClass.reflist() is directly or indirectly doing an improper String comparison by using the == operator rather than String.equals(). See this article for an explanation of the difference.
The problem
Here's a demonstration of the problem:
def a = 'whatever'
def b = 'what' + 'ever'
assert doSomething('whatever') == 'OK'
assert doSomething(a) == 'OK'
assert doSomething(b) == 'ERROR'
def doSomething(String value) {
if(value.is('whatever')) { // In Java this would be: value == "whatever"
'OK'
} else {
'ERROR'
}
}
Because it's using reference equality, which in Groovy is done by the Object.is(Object) method, BrokenClass.reflist() was inadvertently coded to work only with String literals: all String literals with the same value refer to the same String instance, resulting in an evaluation of True. A String composed at run time with the same value of a literal does not refer to the same String instance.
Work around
Obviously BrokenClass.reflist() should be fixed. But you can work around the problem by using an interned String.
def b = 'what' + 'ever'
assert doSomething(b.intern()) == 'OK'
def doSomething(String value) {
if(value.is('whatever')) {
'OK'
} else {
'ERROR'
}
}
If the variable's value matches that of a String literal, then variable.intern() will return the same String instance as the matching literal. This would allow the Java == operator to work as you need it to.
For example, instance of the following following class produces string A(x:7, values:[hello, world])
#ToString( includeNames=true )
class A {
def x
def values = []
}
How can I transform this String back to an instance of the class?
Based on the comments by #cfrick, this is not possible.
(Answering my own question for the sake of closing this topic.)
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.
You are right: since Console class is final, it could not be extended. So, the solution should go in another direction:
Create new class MockConsole, not inherited from Console, but having the same methods.
Change the constructor of MyClass this way:
MyClass(cons = null) {
this.cons = cons ?: System.console()
}
Instantiate MockConsole in spock test and pass it to MyClass constructor.
update-201312272156
I played with spock a little bit. The problem with mocking "readLine(String fmt, Object ... args)" seems to be specific to varargs (or to last arg being a list, which is the same to groovy). I managed to reduce a problem to the following scenario:
Define an interface:
interface IConsole {
String readLine(String fmt, Object ... args)
}
Define test:
class TestInputMethods extends Specification {
def 'test console input'() {
setup:
def consoleMock = GroovyMock(IConsole)
1 * consoleMock.readLine(_) >> 'validResponse'
when:
// here we get exception "wrong number of arguments":
def testResult = consoleMock.readLine('testPrompt')
then:
testResult == 'validResponse'
}
}
this variant of test fails with exception "wrong number of arguments". Particularly, spock thinks that readLine accepts 2 arguments and ignores the fact that second argument is vararg. Proof: if we remove "Object ... args" from IConsole.readLine, the test completes successfully.
Here is Workaround for this (hopefully temporary) problem: change the call to readLine to:
def testResult = consoleMock.readLine('testPrompt', [] as Object[])
then test completes successfully.
I also tried the same code against spock 1.0-groovy-2.0-SNAPSHOT - the problem is the same.
update-201312280030
The problem with varargs is solved! Many thanks to #charlesg, who answered my related question at: Spock: mock a method with varargs
The solution is the following: replace GroovyMock with Mock, then varargs are properly interpreted.
I am wondering if I can pass variable to be evaluated as String inside gstring evaluation.
simplest example will be some thing like
def var ='person.lName'
def value = "${var}"
println(value)
I am looking to get output the value of lastName in the person instance. As a last resort I can use reflection, but wondering there should be some thing simpler in groovy, that I am not aware of.
Can you try:
def var = Eval.me( 'new Date()' )
In place of the first line in your example.
The Eval class is documented here
edit
I am guessing (from your updated question) that you have a person variable, and then people are passing in a String like person.lName , and you want to return the lName property of that class?
Can you try something like this using GroovyShell?
// Assuming we have a Person class
class Person {
String fName
String lName
}
// And a variable 'person' stored in the binding of the script
person = new Person( fName:'tim', lName:'yates' )
// And given a command string to execute
def commandString = 'person.lName'
GroovyShell shell = new GroovyShell( binding )
def result = shell.evaluate( commandString )
Or this, using direct string parsing and property access
// Assuming we have a Person class
class Person {
String fName
String lName
}
// And a variable 'person' stored in the binding of the script
person = new Person( fName:'tim', lName:'yates' )
// And given a command string to execute
def commandString = 'person.lName'
// Split the command string into a list based on '.', and inject starting with null
def result = commandString.split( /\./ ).inject( null ) { curr, prop ->
// if curr is null, then return the property from the binding
// Otherwise try to get the given property from the curr object
curr?."$prop" ?: binding[ prop ]
}