How to give System property to my test via Gradle and -D

I have a a Java program which reads a System property

System.getProperty("cassandra.ip");

and I have a Gradle build file that I start with

gradle test -Pcassandra.ip=192.168.33.13

or

gradle test -Dcassandra.ip=192.168.33.13

however System.getProperty will always return null.

The only way I found was to add that in my Gradle build file via

test {
    systemProperty "cassandra.ip", "192.168.33.13"
}

How Do I do it via -D

The -P flag is for gradle properties, and the -D flag is for JVM properties. Because the test may be forked in a new JVM, the -D argument passed to gradle will not be propagated to the test - it sounds like that is the behavior you are seeing.

You can use the systemProperty in your test block as you have done but base it on the incoming gradle property by passing it with it -P:

test {
    systemProperty "cassandra.ip", project.getProperty("cassandra.ip")
}

or alternatively, if you are passing it in via -D

test {
    systemProperty "cassandra.ip", System.getProperty("cassandra.ip")
}

Came across this very much problem, except i don't want to list all properties given on the commandline in the gradle script again. Therefore i send all system properties to my test

task integrationTest(type: Test) {
    useTestNG()
    options {
        systemProperties(System.getProperties())
    }
}

I had a case where I needed to pass multiple system properties into the test JVM but not all (didn't want to pass in irrelevant ones). Based on the above answers, and by using subMap to filter the ones I needed, this worked for me:

task integrationTest(type: Test) {
    // ... Do stuff here ...
    systemProperties System.getProperties().subMap(['PROP1', 'PROP2'])
}

In this example, only PROP1 and PROP2 will be passed in, if they exist in gradle's JVM.

Here's a variant that passes numerous project properties to the test JVM as system properties. I prefer project properties over system properties to increase flexibility.

task intTest(type: Test) {
    systemProperties project.properties.subMap(["foo", "bar"])
}

Which may be passed on the command-line:

 $ gradle intTest -Pfoo=1 -Pbar=2

And retrieved in your test:

String foo = System.getProperty("foo");

So I've stumbled on that issue today as well, and what worked for me was the following:

ext.env='prod'
test {
  systemProperty 'env', System.properties['env'] ?: "${env}"
  println "# test environment: " + systemProperties['env']
  ...
}

I'm calling my test task using -Penv=dev and I get my 'dev' value in my print, or 'prod' if I do not send any value, which is the expected behavior for me.

Value is also accessible on java side, using System.getProperty("env").

My conclusion on the matter is that input value (parameter) is actually stored under System, making it accessible through either System.properties['env'] or System.getProperty("env"), whereas output (system property) is stored in a systemProperties array, making it readable through systemProperties['env'].

Here is something that worked for me

//in build.gradle file

    tasks.withType(Test) {
        systemProperties = [           ip: System.getProperty('ip', '192.168.33.13'),        ]
    }

    task integrationTests(type: Test){
        useTestNG()
    }

Suppose if you are using TestNG, you can add the annotation @Parameters as shown below

  public class IpAddress {
    @Test
    @Parameters("ip")
    public void printIpAddress(String ip) {
        System.out.println(ip);
    }
 }

Now you are good to execute a gradlew command

./gradlew clean -Dip="xx.xx.xx.xx" integrationTests --tests "IpAddress"

If you want to use @DataProvider to pass the test data, you can pass it like below and execute the same above gradle command to run the test

 public class IpAddress {
    @DataProvider(name = "GetIP")
    private static Object[][] getIp() {
        return new Object[][]{
                //if -Dip is not provided in command, then by default it gets the value assigned in build.gradle file i.e.'192.168.33.13'
                {System.getProperty("ip")}, 
        };
    }

    @Test(dataProvider = "GetIP")
    public void printIpAddress(String ip) {
        System.out.println(ip);
    }
}