Microprofile | Config - Testing with dynamic values

Question

I am using Microprofile Config (@Inject, not ConfigProvider) in my application. I have a configuration that takes different branches for different values. In order to test (Arquillian) all paths in my code, I need to be able to change this value at runtime. Can someone offer tips on how to achieve this? My properties are set using system properties, but I'm open to ideas on how to handle this.

Answer 1

You could register a ConfigSource which can be configured easily. You can look at the one I wrote one for the mp-config TCK itself: https://github.com/eclipse/microprofile-config/blob/master/tck/src/main/java/org/eclipse/microprofile/config/tck/configsources/ConfigurableConfigSource.java

For adding this ConfigSource to your Arquillian @Deployment check this test: https://github.com/eclipse/microprofile-config/blob/1499b7bf734eb1710fe3b7fbdbbcb1ca0983e4cd/tck/src/main/java/org/eclipse/microprofile/config/tck/ConfigAccessorTest.java#L52

The important lines are:

.addClass(ConfigurableConfigSource.class)
.addAsServiceProvider(ConfigSource.class, ConfigurableConfigSource.class)

And then tweak the values

ConfigurableConfigSource.configure(config, "my.config.entry", "some new value");

Answer 2

Regarding to the Microprofile Config: Spec: Configsource which mentions as the following: -

System properties (default ordinal=400).

Environment variables (default ordinal=300).

A ConfigSource for each property file META-INF/microprofile-config.properties found on the classpath. (default ordinal = 100).

This means the system properties is a highest priority here. Then we may set the default value at the META-INF/microprofile-config.properties and override it if needed by the system properties instead.

During the integration test we are able to set the system properties together with use the javax.inject.Provider to make it retrieving dynamically so that the default value is overridden as the following example :-

# META-INF/microprofile-config.properties
my.key=original

import javax.inject.Inject;
import javax.inject.Provider;

import org.eclipse.microprofile.config.inject.ConfigProperty;

public class SomeClass {
    @Inject
    @ConfigProperty(
        name = "my.key"
    )
    private Provider<String> key1;

    public String doSomethingWithConfig() {
        return key1.get();
    }
}

import javax.inject.Inject;
import org.jboss.arquillian.junit.Arquillian;
import org.jboss.arquillian.junit.InSequence;
import org.junit.Test;
import org.junit.Assert;

@RunWith(Arquillian.class)
public class SomeClassTester {

    @Inject
    private SomeClass someclass;

    @Test
    @InSequence(1)
    public void whenTestDefaultConfig() {
        Assert.assertEquals("The value must be a defualt.",
                            "original", 
                            this.someclass.doSomethingWithConfig());
    }

    @Test
    @InSequence(2)
    public void whenTestOverrideMPConfig() {

        System.setProperty("my.key",
                           "new-value");
        Assert.assertEquals("The value must be overridden",
                            "new-value", 
                            this.someclass.doSomethingWithConfig());
    }

}

EDIT1

Furthermore if we would like to take control over the system properites, the System Rules will make our live easier. They provide ClearSystemProperties, ProvideSystemProperty and RestoreSystemProperties as the following example from their document.

public class MyTest {
    @Rule
    public final RestoreSystemProperties restoreSystemProperties
     = new RestoreSystemProperties();

    @Test
    public void overrideProperty() {
        //after the test the original value of "MyProperty" will be restored.
        System.setProperty("MyProperty", "other value");
        ...
    }

}