Assume NG -- Assumptions for TestNG

Using Assume NG it becomes possible to add JUnit-like assumptions to TestNG.

Usage

Assume NG can work in one of either two ways:

• Using the @Assumption annotation and the AssumptionListener
• Using the Assumes.assumeThat(...) method

When a assumption fails, TestNG will be instructed to ignore the test case and will thus not execute it.

Which one you choose is mostly personal preference. The biggest difference is that with the @Assumption annotation Assume NG will inform you of all the failed assumptions, whereas with the assumeThat method call it will only inform you that a single assumption failed. On the other hand with the assumeThat method you can give more comprehensive messages on why the test was skipped.

@Assumption annotation

The @Assumption annotation is defined on a @Test method, and calls out to one or more assumption methods which decide whether or not the @Test annotated method needs to run in the current context. Only if all of the assumption methods pass, the @Test method will actually be invoked, otherwise it will be marked as skipped.

The AssumptionListener scans for @Assumption annotations and handles the actual invocation of the assumption method.

The signature of an assumption method should return a boolean and take no arguments. Such as:

public boolean checkWhetherXHolds() { ... }

A simple usage example is:

@Listeners(AssumptionListener.class)
public class WeatherTest {
    @Test
    @Assumption(methods = "assumeWeatherIsNice")
    public void shouldNotRunWhenItsRaining() {
        // Do some stuff, like going to the beach...
    }

    public boolean assumeWeatherIsNice() {
        // check the weather bulletin...
    }
}

"Real world" use case:

public class HostFactoryItest {
    @Factory
    public Object[] createTestInstances() {
        Object[] instances = new Object[6];
        object[0] = new HostItest("localhost", "local");
        object[1] = new HostItest("unix-host", "sftp");
        object[2] = new HostItest("unix-host", "ssh");
        object[3] = new HostItest("windows-host", "sftp");
        object[4] = new HostItest("windows-host", "cifs-telnet");
        object[5] = new HostItest("windows-host", "cifs-winrm");
    }
}

@Listeners(AssumptionListener.class)
public class HostItest() {
    private String host;
    private String protocol;

    public HostItest(String host, String protocol) {
        ...
    }

    @Test
    @Assumption(methods = "notLocal")
    public void shouldNotConnectUsingWrongPassword() {
        ...
    }

    @Test
    public void shouldGetFileFromHost() {
        ...
    }

    ...more tests...

    public boolean notLocal() {
        return !this.host.equals("localhost");
    }
}

Assumptions.assumeThat(...)

Similarly to JUnit, we've added a few variants of the assumeThat(...) method call that can be used in order to verify assumptions. A small usage example:

public class WeatherTest {
    @Test
    public void shouldNotRunWhenItsRaining() {
        assumeThat("It's raining outside, let's not run this test now.", assumeWeatherIsNice());
        // Do some stuff, like going to the beach...
    }

    public boolean assumeWeatherIsNice() {
        // check the weather bulletin...
    }
}