Add MultiTenantAuthenticationManagerResolver

A class with a number of handy request-based implementations of
AuthenticationManagerResolver targeted at common multi-tenancy
scenarios.

Fixes: gh-6976

web/src/test/java/org/springframework/security/web/authentication/MultiTenantAuthenticationManagerResolverTests.java

@@ -0,0 +1,159 @@
+/*
+ * Copyright 2002-2019 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
+ *
+ *      https://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.web.authentication;
+
+import java.util.Collections;
+import java.util.Map;
+import javax.servlet.http.HttpServletRequest;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.Mock;
+import org.mockito.junit.MockitoJUnitRunner;
+
+import org.springframework.core.convert.converter.Converter;
+import org.springframework.security.authentication.AuthenticationManager;
+import org.springframework.security.authentication.AuthenticationManagerResolver;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatCode;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+import static org.springframework.security.web.authentication.MultiTenantAuthenticationManagerResolver.resolveFromSubdomain;
+import static org.springframework.security.web.authentication.MultiTenantAuthenticationManagerResolver.resolveFromPath;
+import static org.springframework.security.web.authentication.MultiTenantAuthenticationManagerResolver.resolveFromHeader;
+
+/**
+ * Tests for {@link MultiTenantAuthenticationManagerResolver}
+ */
+@RunWith(MockitoJUnitRunner.class)
+public class MultiTenantAuthenticationManagerResolverTests {
+	private static final String TENANT = "tenant";
+
+	@Mock
+	AuthenticationManager authenticationManager;
+
+	@Mock
+	HttpServletRequest request;
+
+	Map<String, AuthenticationManager> authenticationManagers;
+
+	@Before
+	public void setup() {
+		this.authenticationManagers = Collections.singletonMap(TENANT, this.authenticationManager);
+	}
+
+	@Test
+	public void resolveFromSubdomainWhenGivenResolverThenReturnsSubdomainParsingResolver() {
+		AuthenticationManagerResolver<HttpServletRequest> fromSubdomain =
+				resolveFromSubdomain(this.authenticationManagers::get);
+
+		when(this.request.getServerName()).thenReturn(TENANT + ".example.org");
+
+		AuthenticationManager authenticationManager = fromSubdomain.resolve(this.request);
+		assertThat(authenticationManager).isEqualTo(this.authenticationManager);
+
+		when(this.request.getServerName()).thenReturn("wrong.example.org");
+
+		assertThatCode(() -> fromSubdomain.resolve(this.request))
+				.isInstanceOf(IllegalArgumentException.class);
+
+		when(this.request.getServerName()).thenReturn("example");
+
+		assertThatCode(() -> fromSubdomain.resolve(this.request))
+				.isInstanceOf(IllegalArgumentException.class);
+	}
+
+	@Test
+	public void resolveFromPathWhenGivenResolverThenReturnsPathParsingResolver() {
+		AuthenticationManagerResolver<HttpServletRequest> fromPath =
+				resolveFromPath(this.authenticationManagers::get);
+
+		when(this.request.getRequestURI()).thenReturn("/" + TENANT + "/otherthings");
+
+		AuthenticationManager authenticationManager = fromPath.resolve(this.request);
+		assertThat(authenticationManager).isEqualTo(this.authenticationManager);
+
+		when(this.request.getRequestURI()).thenReturn("/otherthings");
+
+		assertThatCode(() -> fromPath.resolve(this.request))
+				.isInstanceOf(IllegalArgumentException.class);
+
+		when(this.request.getRequestURI()).thenReturn("/");
+
+		assertThatCode(() -> fromPath.resolve(this.request))
+				.isInstanceOf(IllegalArgumentException.class);
+	}
+
+	@Test
+	public void resolveFromHeaderWhenGivenResolverTheReturnsHeaderParsingResolver() {
+		AuthenticationManagerResolver<HttpServletRequest> fromHeader =
+				resolveFromHeader("X-Tenant-Id", this.authenticationManagers::get);
+
+		when(this.request.getHeader("X-Tenant-Id")).thenReturn(TENANT);
+
+		AuthenticationManager authenticationManager = fromHeader.resolve(this.request);
+		assertThat(authenticationManager).isEqualTo(this.authenticationManager);
+
+		when(this.request.getHeader("X-Tenant-Id")).thenReturn("wrong");
+
+		assertThatCode(() -> fromHeader.resolve(this.request))
+				.isInstanceOf(IllegalArgumentException.class);
+
+		when(this.request.getHeader("X-Tenant-Id")).thenReturn(null);
+
+		assertThatCode(() -> fromHeader.resolve(this.request))
+				.isInstanceOf(IllegalArgumentException.class);
+	}
+
+	@Test
+	public void resolveWhenGivenTenantResolverThenResolves() {
+		AuthenticationManagerResolver<HttpServletRequest> byRequestConverter =
+				new MultiTenantAuthenticationManagerResolver<>(HttpServletRequest::getQueryString,
+						this.authenticationManagers::get);
+
+		when(this.request.getQueryString()).thenReturn(TENANT);
+
+		AuthenticationManager authenticationManager = byRequestConverter.resolve(this.request);
+		assertThat(authenticationManager).isEqualTo(this.authenticationManager);
+
+		when(this.request.getQueryString()).thenReturn("wrong");
+
+		assertThatCode(() -> byRequestConverter.resolve(this.request))
+				.isInstanceOf(IllegalArgumentException.class);
+
+		when(this.request.getQueryString()).thenReturn(null);
+
+		assertThatCode(() -> byRequestConverter.resolve(this.request))
+				.isInstanceOf(IllegalArgumentException.class);
+	}
+
+	@Test
+	public void constructorWhenUsingNullTenantResolverThenException() {
+		assertThatCode(() -> new MultiTenantAuthenticationManagerResolver
+				(null, mock(Converter.class)))
+				.isInstanceOf(IllegalArgumentException.class);
+	}
+
+	@Test
+	public void constructorWhenUsingNullAuthenticationManagerResolverThenException() {
+		assertThatCode(() -> new MultiTenantAuthenticationManagerResolver
+				(mock(Converter.class), null))
+				.isInstanceOf(IllegalArgumentException.class);
+	}
+}