Add DelegatingReactiveAuthenticationManager

Fixes: gh-5448

core/src/main/java/org/springframework/security/authentication/DelegatingReactiveAuthenticationManager.java

@@ -0,0 +1,55 @@
+/*
+ * Copyright 2002-2018 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.security.authentication;
+
+import java.util.Arrays;
+import java.util.List;
+
+import org.springframework.security.core.Authentication;
+import org.springframework.util.Assert;
+
+import reactor.core.publisher.Flux;
+import reactor.core.publisher.Mono;
+
+/**
+ * A {@link ReactiveAuthenticationManager} that delegates to other {@link ReactiveAuthenticationManager} instances using
+ * the result from the first non empty result.
+ *
+ * @author Rob Winch
+ * @since 5.1
+ */
+public class DelegatingReactiveAuthenticationManager
+		implements ReactiveAuthenticationManager {
+	private final List<ReactiveAuthenticationManager> delegates;
+
+	public DelegatingReactiveAuthenticationManager(
+			ReactiveAuthenticationManager... entryPoints) {
+		this(Arrays.asList(entryPoints));
+	}
+
+	public DelegatingReactiveAuthenticationManager(
+			List<ReactiveAuthenticationManager> entryPoints) {
+		Assert.notEmpty(entryPoints, "entryPoints cannot be null");
+		this.delegates = entryPoints;
+	}
+
+	public Mono<Authentication> authenticate(Authentication authentication) {
+		return Flux.fromIterable(this.delegates)
+				.concatMap(m -> m.authenticate(authentication))
+				.next();
+	}
+}

core/src/test/java/org/springframework/security/authentication/DelegatingReactiveAuthenticationManagerTests.java

@@ -0,0 +1,80 @@
+/*
+ * Copyright 2002-2018 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.security.authentication;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.Mock;
+import org.mockito.junit.MockitoJUnitRunner;
+import org.springframework.security.core.Authentication;
+import reactor.core.publisher.Mono;
+import reactor.test.StepVerifier;
+
+import java.time.Duration;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.when;
+
+/**
+ * @author Rob Winch
+ * @since 5.1
+ */
+@RunWith(MockitoJUnitRunner.class)
+public class DelegatingReactiveAuthenticationManagerTests {
+	@Mock
+	ReactiveAuthenticationManager delegate1;
+
+	@Mock
+	ReactiveAuthenticationManager delegate2;
+
+	@Mock
+	Authentication authentication;
+
+	@Test
+	public void authenticateWhenEmptyAndNotThenReturnsNotEmpty() {
+		when(this.delegate1.authenticate(any())).thenReturn(Mono.empty());
+		when(this.delegate2.authenticate(any())).thenReturn(Mono.just(this.authentication));
+
+		DelegatingReactiveAuthenticationManager manager = new DelegatingReactiveAuthenticationManager(this.delegate1, this.delegate2);
+
+		assertThat(manager.authenticate(this.authentication).block()).isEqualTo(this.authentication);
+	}
+
+	@Test
+	public void authenticateWhenNotEmptyThenOtherDelegatesNotSubscribed() {
+		// delay to try and force delegate2 to finish (i.e. make sure we didn't use flatMap)
+		when(this.delegate1.authenticate(any())).thenReturn(Mono.just(this.authentication).delayElement(Duration.ofMillis(100)));
+
+		DelegatingReactiveAuthenticationManager manager = new DelegatingReactiveAuthenticationManager(this.delegate1, this.delegate2);
+
+		StepVerifier.create(manager.authenticate(this.authentication))
+			.expectNext(this.authentication)
+			.verifyComplete();
+	}
+
+	@Test
+	public void authenticateWhenBadCredentialsThenDelegate2NotInvokedAndError() {
+		when(this.delegate1.authenticate(any())).thenReturn(Mono.error(new BadCredentialsException("Test")));
+
+		DelegatingReactiveAuthenticationManager manager = new DelegatingReactiveAuthenticationManager(this.delegate1, this.delegate2);
+
+		StepVerifier.create(manager.authenticate(this.authentication))
+			.expectError(BadCredentialsException.class)
+			.verify();
+	}
+}