xds: allow injecting bootstrapOverride in xdsNameResolverProvider

xds/src/main/java/io/grpc/xds/SharedXdsClientPoolProvider.java

@@ -52,7 +52,7 @@ final class SharedXdsClientPoolProvider implements XdsClientPoolFactory {
   private final AtomicReference<Map<String, ?>> bootstrapOverride = new AtomicReference<>();
   private volatile ObjectPool<XdsClient> xdsClientPool;
 
-  private SharedXdsClientPoolProvider() {
+  SharedXdsClientPoolProvider() {
     this(new BootstrapperImpl());
   }
 

xds/src/main/java/io/grpc/xds/XdsNameResolver.java

@@ -140,7 +140,8 @@ final class XdsNameResolver extends NameResolver {
     this.serviceConfigParser = checkNotNull(serviceConfigParser, "serviceConfigParser");
     this.syncContext = checkNotNull(syncContext, "syncContext");
     this.scheduler = checkNotNull(scheduler, "scheduler");
-    this.xdsClientPoolFactory = checkNotNull(xdsClientPoolFactory, "xdsClientPoolFactory");
+    this.xdsClientPoolFactory = bootstrapOverride == null ? checkNotNull(xdsClientPoolFactory,
+            "xdsClientPoolFactory") : new SharedXdsClientPoolProvider();
     this.xdsClientPoolFactory.setBootstrapOverride(bootstrapOverride);
     this.random = checkNotNull(random, "random");
     this.filterRegistry = checkNotNull(filterRegistry, "filterRegistry");

xds/src/main/java/io/grpc/xds/XdsNameResolverProvider.java

@@ -41,19 +41,22 @@
 @Internal
 public final class XdsNameResolverProvider extends NameResolverProvider {
 
-  private String scheme = "xds";
-  private Map<String, ?> bootstrapOverride;
+  private static final String SCHEME = "xds";
+  private final String scheme;
+  private final Map<String, ?> bootstrapOverride;
+
+  public XdsNameResolverProvider() {
+    this(SCHEME, null);
+  }
 
   /**
-   * A convenient method to create a {@link XdsNameResolverProvider} with custom scheme and
-   * bootstrap.
+   * A convenient constructor to allow creating a {@link XdsNameResolverProvider} with custom scheme
+   * and bootstrap.
    */
-  public static XdsNameResolverProvider createForTest(String scheme,
-                                               @Nullable Map<String, ?> bootstrapOverride) {
-    XdsNameResolverProvider provider = new XdsNameResolverProvider();
-    provider.scheme = checkNotNull(scheme, "scheme");
-    provider.bootstrapOverride = bootstrapOverride;
-    return provider;
+  public XdsNameResolverProvider(String scheme,
+                                 @Nullable Map<String, ?> bootstrapOverride) {
+    this.scheme = checkNotNull(scheme, "scheme");
+    this.bootstrapOverride = bootstrapOverride;
   }
 
   @Override

xds/src/test/java/io/grpc/xds/XdsNameResolverProviderTest.java

@@ -121,13 +121,15 @@ public void invalidName_hostnameContainsUnderscore() {
   }
 
   @Test
-  public void newProvider_createForTest() {
-    NameResolverRegistry registry = new NameResolverRegistry();
-    XdsNameResolverProvider provider0 = XdsNameResolverProvider.createForTest("no-scheme", null);
+  public void newProvider_multipleScheme() {
+    NameResolverRegistry registry = NameResolverRegistry.getDefaultRegistry();
+    XdsNameResolverProvider provider0 = new XdsNameResolverProvider("no-scheme", null);
     registry.register(provider0);
-    XdsNameResolverProvider provider1 = XdsNameResolverProvider.createForTest("new-xds-scheme",
+    XdsNameResolverProvider provider1 = new XdsNameResolverProvider("new-xds-scheme",
             new HashMap<String, String>());
     registry.register(provider1);
+    assertThat(registry.asFactory()
+            .newNameResolver(URI.create("xds:///localhost"), args)).isNotNull();
     assertThat(registry.asFactory()
             .newNameResolver(URI.create("new-xds-scheme:///localhost"), args)).isNotNull();
     assertThat(registry.asFactory()
@@ -136,10 +138,12 @@ public void newProvider_createForTest() {
     assertThat(registry.asFactory()
             .newNameResolver(URI.create("new-xds-scheme:///localhost"), args)).isNull();
     registry.deregister(provider0);
+    assertThat(registry.asFactory()
+            .newNameResolver(URI.create("xds:///localhost"), args)).isNotNull();
   }
 
   @Test
-  public void newProvider_createForTest_overrideBootstrap() {
+  public void newProvider_overrideBootstrap() {
     Map<String, ?> b = ImmutableMap.of(
             "node", ImmutableMap.of(
                     "id", "ENVOY_NODE_ID",
@@ -154,14 +158,15 @@ public void newProvider_createForTest_overrideBootstrap() {
             )
     );
     NameResolverRegistry registry = new NameResolverRegistry();
-    XdsNameResolverProvider provider = XdsNameResolverProvider.createForTest("no-scheme", b);
+    XdsNameResolverProvider provider = new XdsNameResolverProvider("no-scheme", b);
     registry.register(provider);
     NameResolver resolver = registry.asFactory()
             .newNameResolver(URI.create("no-scheme:///localhost"), args);
     resolver.start(mock(NameResolver.Listener2.class));
     assertThat(resolver).isInstanceOf(XdsNameResolver.class);
     assertThat(((XdsNameResolver)resolver).getXdsClient().getBootstrapInfo().getNode().getId())
             .isEqualTo("ENVOY_NODE_ID");
+    resolver.shutdown();
     registry.deregister(provider);
   }
 }

xds/src/test/java/io/grpc/xds/XdsNameResolverTest.java

@@ -83,7 +83,6 @@
 import java.io.IOException;
 import java.util.Arrays;
 import java.util.Collections;
-import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.concurrent.ScheduledExecutorService;
@@ -186,9 +185,8 @@ public ObjectPool<XdsClient> getOrCreate() throws XdsInitializationException {
         throw new XdsInitializationException("Fail to read bootstrap file");
       }
     };
-    Map<String, String> b = new HashMap<>();
     resolver = new XdsNameResolver(AUTHORITY, serviceConfigParser, syncContext, scheduler,
-        xdsClientPoolFactory, mockRandom, FilterRegistry.getDefaultRegistry(), b);
+        xdsClientPoolFactory, mockRandom, FilterRegistry.getDefaultRegistry(), null);
     resolver.start(mockListener);
     verify(mockListener).onError(errorCaptor.capture());
     Status error = errorCaptor.getValue();