/
InstanceIdentifierSupplierTest.java
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/
InstanceIdentifierSupplierTest.java
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/*
* Copyright (c) 2019 Contributors to the Eclipse Foundation
*
* See the NOTICE file(s) distributed with this work for additional
* information regarding copyright ownership.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License 2.0 which is available at
* http://www.eclipse.org/legal/epl-2.0
*
* SPDX-License-Identifier: EPL-2.0
*/
package org.eclipse.ditto.services.utils.config;
import static org.assertj.core.api.Assertions.assertThat;
import static org.mutabilitydetector.unittesting.AllowedReason.assumingFields;
import static org.mutabilitydetector.unittesting.MutabilityAssert.assertInstancesOf;
import static org.mutabilitydetector.unittesting.MutabilityMatchers.areImmutable;
import java.lang.reflect.Constructor;
import org.junit.Before;
import org.junit.Rule;
import org.junit.Test;
import org.junit.contrib.java.lang.system.EnvironmentVariables;
/**
* Unit test for {@link InstanceIdentifierSupplier}.
*/
public final class InstanceIdentifierSupplierTest {
@Rule
public EnvironmentVariables environmentVariables = new EnvironmentVariables();
@Before
public void setUp() {
environmentVariables.clear(InstanceIdentifierSupplier.ENV_INSTANCE_INDEX);
}
@Test
public void assertImmutability() {
assertInstancesOf(InstanceIdentifierSupplier.class,
areImmutable(),
assumingFields("instanceIdentifier").areModifiedAsPartOfAnUnobservableCachingStrategy());
}
@Test
public void getInstanceReturnsSingleton() {
final InstanceIdentifierSupplier firstObtainedInstance = InstanceIdentifierSupplier.getInstance();
final InstanceIdentifierSupplier secondObtainedInstance = InstanceIdentifierSupplier.getInstance();
assertThat(firstObtainedInstance).isSameAs(secondObtainedInstance);
}
@Test
public void instanceIndexIsObtainedFromEnvironmentVariable() {
final String instanceIndex = "foo-service:3";
environmentVariables.set(InstanceIdentifierSupplier.ENV_INSTANCE_INDEX, instanceIndex);
final InstanceIdentifierSupplier underTest = InstanceIdentifierSupplier.getInstance();
assertThat(underTest.get()).isEqualTo(instanceIndex);
}
@Test
public void instanceIndexIsObtainedFromHostNameSupplier() {
final HostNameSupplier hostNameSupplier = HostNameSupplier.getInstance();
final String instanceIndex = hostNameSupplier.get();
final InstanceIdentifierSupplier underTest = tryToGetInstancePerReflection();
assertThat(underTest.get()).isEqualTo(instanceIndex);
}
private static InstanceIdentifierSupplier tryToGetInstancePerReflection() {
try {
return getInstancePerReflection();
} catch (final Exception e) {
throw new IllegalStateException("Failed to create object of InstanceIdentifierSupplier per reflection!", e);
}
}
/**
* Returns an object of {@link InstanceIdentifierSupplier} which was created by reflection to circumvent a
* possibly cached instance index.
*/
private static InstanceIdentifierSupplier getInstancePerReflection() throws Exception {
final Constructor<InstanceIdentifierSupplier> ctor = InstanceIdentifierSupplier.class.getDeclaredConstructor();
ctor.setAccessible(true);
return ctor.newInstance();
}
}