core/src/test/java/io/grpc/internal/DnsNameResolverProviderTest.java

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package io.grpc.internal;

import static org.junit.Assert.assertNull;
import static org.junit.Assert.assertSame;
import static org.junit.Assert.assertTrue;
import static org.junit.Assert.fail;

import io.grpc.Attributes;
import io.grpc.NameResolverProvider;

import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.JUnit4;

import java.net.URI;

/** Unit tests for {@link DnsNameResolverProvider}. */
@RunWith(JUnit4.class)
public class DnsNameResolverProviderTest {
  private DnsNameResolverProvider provider = new DnsNameResolverProvider();

  @Test
  public void provided() {
    for (NameResolverProvider current
        : NameResolverProvider.getCandidatesViaServiceLoader(getClass().getClassLoader())) {
      if (current instanceof DnsNameResolverProvider) {
        return;
      }
    }
    fail("DnsNameResolverProvider not registered");
  }

  @Test
  public void providedHardCoded() {
    for (NameResolverProvider current
        : NameResolverProvider.getCandidatesViaHardCoded(getClass().getClassLoader())) {
      if (current instanceof DnsNameResolverProvider) {
        return;
      }
    }
    fail("DnsNameResolverProvider not registered");
  }

  @Test
  public void isAvailable() {
    assertTrue(provider.isAvailable());
  }

  @Test
  public void newNameResolver() {
    assertSame(DnsNameResolver.class,
        provider.newNameResolver(URI.create("dns:///localhost:443"), Attributes.EMPTY).getClass());
    assertNull(
        provider.newNameResolver(URI.create("notdns:///localhost:443"), Attributes.EMPTY));
  }
}