Create TenantManager class and wire through listTenants operation.

src/main/java/com/google/firebase/auth/AbstractFirebaseAuth.java

@@ -690,8 +690,7 @@ protected UserRecord execute() throws FirebaseAuthException {
    * UpdateRequest}.
    *
    * @param request A non-null {@link UpdateRequest} instance.
-   * @return A {@link UserRecord} instance corresponding to the updated user account. account, the
-   *     task fails with a {@link FirebaseAuthException}.
+   * @return A {@link UserRecord} instance corresponding to the updated user account.
    * @throws NullPointerException if the provided update request is null.
    * @throws FirebaseAuthException if an error occurs while updating the user account.
    */
@@ -1053,7 +1052,6 @@ public ApiFuture<String> generateSignInWithEmailLinkAsync(
         .callAsync(firebaseApp);
   }
 
-  @VisibleForTesting
   FirebaseUserManager getUserManager() {
     return this.userManager.get();
   }
@@ -1074,7 +1072,7 @@ protected String execute() throws FirebaseAuthException {
     };
   }
 
-  private <T> Supplier<T> threadSafeMemoize(final Supplier<T> supplier) {
+  protected <T> Supplier<T> threadSafeMemoize(final Supplier<T> supplier) {
     checkNotNull(supplier);
     return Suppliers.memoize(
         new Supplier<T>() {

src/main/java/com/google/firebase/auth/FirebaseAuth.java

@@ -31,19 +31,29 @@
  * then use it to perform a variety of authentication-related operations, including generating
  * custom tokens for use by client-side code, verifying Firebase ID Tokens received from clients, or
  * creating new FirebaseApp instances that are scoped to a particular authentication UID.
- * 
- * <p>TODO(micahstairs): Add getTenantManager() method.
  */
 public class FirebaseAuth extends AbstractFirebaseAuth {
 
   private static final String SERVICE_ID = FirebaseAuth.class.getName();
 
-  private FirebaseAuth(Builder builder) {
+  private final Supplier<TenantManager> tenantManager;
+
+  private FirebaseAuth(final Builder builder) {
     super(
         builder.firebaseApp,
         builder.tokenFactory,
         builder.idTokenVerifier,
         builder.cookieVerifier);
+    tenantManager = threadSafeMemoize(new Supplier<TenantManager>() {
+      @Override
+      public TenantManager get() {
+        return new TenantManager(builder.firebaseApp, getUserManager());
+      }
+    });
+  }
+
+  public TenantManager getTenantManager() {
+    return tenantManager.get();
   }
 
   /**

src/main/java/com/google/firebase/auth/FirebaseUserManager.java

@@ -57,9 +57,8 @@
 /**
  * FirebaseUserManager provides methods for interacting with the Google Identity Toolkit via its
  * REST API. This class does not hold any mutable state, and is thread safe.
- * 
- * <p>TODO(micahstairs): Consider renaming this to FirebaseAuthManager since this also supports
- * tenants.
+ *
+ * <p>TODO(micahstairs): Rename this class to IdentityToolkitClient.
  *
  * @see <a href="https://developers.google.com/identity/toolkit/web/reference/relyingparty">
  *   Google Identity Toolkit</a>
@@ -227,7 +226,8 @@ UserImportResult importUsers(UserImportRequest request) throws FirebaseAuthExcep
     return new UserImportResult(request.getUsersCount(), response);
   }
 
-  ListTenantsResponse listTenants(int maxResults, String pageToken) throws FirebaseAuthException {
+  ListTenantsResponse listTenants(int maxResults, String pageToken)
+      throws FirebaseAuthException {
     ImmutableMap.Builder<String, Object> builder = ImmutableMap.<String, Object>builder()
         .put("pageSize", maxResults);
     if (pageToken != null) {

src/main/java/com/google/firebase/auth/ListTenantsPage.java

@@ -32,10 +32,10 @@
 
 /**
  * Represents a page of {@link Tenant} instances.
- * 
+ *
  * <p>Provides methods for iterating over the tenants in the current page, and calling up
  * subsequent pages of tenants.
- * 
+ *
  * <p>Instances of this class are thread-safe and immutable.
  */
 public class ListTenantsPage implements Page<Tenant> {
@@ -65,7 +65,7 @@ public boolean hasNextPage() {
 
   /**
    * Returns the string token that identifies the next page.
-   * 
+   *
    * <p>Never returns null. Returns empty string if there are no more pages available to be
    * retrieved.
    *
@@ -99,7 +99,7 @@ public ListTenantsPage getNextPage() {
   /**
    * Returns an {@link Iterable} that facilitates transparently iterating over all the tenants in
    * the current Firebase project, starting from this page.
-   * 
+   *
    * <p>The {@link Iterator} instances produced by the returned {@link Iterable} never buffers more
    * than one page of tenants at a time. It is safe to abandon the iterators (i.e. break the loops)
    * at any time.
@@ -139,7 +139,7 @@ public Iterator<Tenant> iterator() {
 
     /**
      * An {@link Iterator} that cycles through tenants, one at a time.
-     * 
+     *
      * <p>It buffers the last retrieved batch of tenants in memory. The {@code maxResults} parameter
      * is an upper bound on the batch size.
      */
@@ -199,11 +199,9 @@ ListTenantsResponse fetch(int maxResults, String pageToken)
   static class DefaultTenantSource implements TenantSource {
 
     private final FirebaseUserManager userManager;
-    private final JsonFactory jsonFactory;
 
-    DefaultTenantSource(FirebaseUserManager userManager, JsonFactory jsonFactory) {
+    DefaultTenantSource(FirebaseUserManager userManager) {
       this.userManager = checkNotNull(userManager, "user manager must not be null");
-      this.jsonFactory = checkNotNull(jsonFactory, "json factory must not be null");
     }
 
     @Override
@@ -215,7 +213,7 @@ public ListTenantsResponse fetch(int maxResults, String pageToken)
 
   /**
    * A simple factory class for {@link ListTenantsPage} instances.
-   * 
+   *
    * <p>Performs argument validation before attempting to load any tenant data (which is expensive,
    * and hence may be performed asynchronously on a separate thread).
    */

src/main/java/com/google/firebase/auth/TenantManager.java

@@ -0,0 +1,118 @@
+/*
+ * Copyright 2020 Google LLC
+ *
+ * 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 com.google.firebase.auth;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+
+import com.google.api.client.json.JsonFactory;
+import com.google.api.core.ApiFuture;
+import com.google.firebase.FirebaseApp;
+import com.google.firebase.auth.ListTenantsPage.DefaultTenantSource;
+import com.google.firebase.auth.ListTenantsPage.PageFactory;
+import com.google.firebase.auth.ListTenantsPage.TenantSource;
+import com.google.firebase.auth.Tenant.CreateRequest;
+import com.google.firebase.auth.Tenant.UpdateRequest;
+import com.google.firebase.internal.CallableOperation;
+import com.google.firebase.internal.NonNull;
+import com.google.firebase.internal.Nullable;
+
+/**
+ * This class can be used to perform a variety of tenant-related operations, including creating,
+ * updating, and listing tenants.
+ *
+ * <p>TODO(micahstairs): Implement the following methods: getAuthForTenant(), getTenant(),
+ * deleteTenant(), createTenant(), and updateTenant().
+ */
+public final class TenantManager {
+
+  private final FirebaseApp firebaseApp;
+  private final FirebaseUserManager userManager;
+
+  TenantManager(FirebaseApp firebaseApp, FirebaseUserManager userManager) {
+    this.firebaseApp = firebaseApp;
+    this.userManager = userManager;
+  }
+
+  /**
+   * Gets a page of tenants starting from the specified {@code pageToken}. Page size will be limited
+   * to 1000 tenants.
+   *
+   * @param pageToken A non-empty page token string, or null to retrieve the first page of tenants.
+   * @return A {@link ListTenantsPage} instance.
+   * @throws IllegalArgumentException If the specified page token is empty.
+   * @throws FirebaseAuthException If an error occurs while retrieving tenant data.
+   */
+  public ListTenantsPage listTenants(@Nullable String pageToken) throws FirebaseAuthException {
+    return listTenants(pageToken, FirebaseUserManager.MAX_LIST_TENANTS_RESULTS);
+  }
+
+  /**
+   * Gets a page of tenants starting from the specified {@code pageToken}.
+   *
+   * @param pageToken A non-empty page token string, or null to retrieve the first page of tenants.
+   * @param maxResults Maximum number of tenants to include in the returned page. This may not
+   *     exceed 1000.
+   * @return A {@link ListTenantsPage} instance.
+   * @throws IllegalArgumentException If the specified page token is empty, or max results value is
+   *     invalid.
+   * @throws FirebaseAuthException If an error occurs while retrieving tenant data.
+   */
+  public ListTenantsPage listTenants(@Nullable String pageToken, int maxResults)
+      throws FirebaseAuthException {
+    return listTenantsOp(pageToken, maxResults).call();
+  }
+
+  /**
+   * Similar to {@link #listTenants(String)} but performs the operation asynchronously.
+   *
+   * @param pageToken A non-empty page token string, or null to retrieve the first page of tenants.
+   * @return An {@code ApiFuture} which will complete successfully with a {@link ListTenantsPage}
+   *     instance. If an error occurs while retrieving tenant data, the future throws an exception.
+   * @throws IllegalArgumentException If the specified page token is empty.
+   */
+  public ApiFuture<ListTenantsPage> listTenantsAsync(@Nullable String pageToken) {
+    return listTenantsAsync(pageToken, FirebaseUserManager.MAX_LIST_TENANTS_RESULTS);
+  }
+
+  /**
+   * Similar to {@link #listTenants(String, int)} but performs the operation asynchronously.
+   *
+   * @param pageToken A non-empty page token string, or null to retrieve the first page of tenants.
+   * @param maxResults Maximum number of tenants to include in the returned page. This may not
+   *     exceed 1000.
+   * @return An {@code ApiFuture} which will complete successfully with a {@link ListTenantsPage}
+   *     instance. If an error occurs while retrieving tenant data, the future throws an exception.
+   * @throws IllegalArgumentException If the specified page token is empty, or max results value is
+   *     invalid.
+   */
+  public ApiFuture<ListTenantsPage> listTenantsAsync(@Nullable String pageToken, int maxResults) {
+    return listTenantsOp(pageToken, maxResults).callAsync(firebaseApp);
+  }
+
+  private CallableOperation<ListTenantsPage, FirebaseAuthException> listTenantsOp(
+      @Nullable final String pageToken, final int maxResults) {
+    // TODO(micahstairs): Add a check to make sure the app has not been destroyed yet.
+    final TenantSource tenantSource = new DefaultTenantSource(userManager);
+    final PageFactory factory = new PageFactory(tenantSource, maxResults, pageToken);
+    return new CallableOperation<ListTenantsPage, FirebaseAuthException>() {
+      @Override
+      protected ListTenantsPage execute() throws FirebaseAuthException {
+        return factory.create();
+      }
+    };
+  }
+}

src/main/java/com/google/firebase/auth/internal/ListTenantsResponse.java

@@ -17,20 +17,24 @@
 package com.google.firebase.auth.internal;
 
 import com.google.api.client.util.Key;
+import com.google.common.annotations.VisibleForTesting;
+import com.google.common.collect.ImmutableList;
+import com.google.firebase.auth.ListTenantsPage;
 import com.google.firebase.auth.Tenant;
 import java.util.List;
 
 /**
  * JSON data binding for ListTenantsResponse messages sent by Google identity toolkit service.
  */
-public class ListTenantsResponse {
+public final class ListTenantsResponse {
 
   @Key("tenants")
   private List<Tenant> tenants;
 
   @Key("pageToken")
   private String pageToken;
 
+  @VisibleForTesting
   public ListTenantsResponse(List<Tenant> tenants, String pageToken) {
     this.tenants = tenants;
     this.pageToken = pageToken;
@@ -39,14 +43,14 @@ public ListTenantsResponse(List<Tenant> tenants, String pageToken) {
   public ListTenantsResponse() { }
 
   public List<Tenant> getTenants() {
-    return tenants;
+    return tenants == null ? ImmutableList.<Tenant>of() : tenants;
   }
 
   public boolean hasTenants() {
     return tenants != null && !tenants.isEmpty();
   }
 
   public String getPageToken() {
-    return pageToken;
+    return pageToken == null ? "" : pageToken;
   }
 }

src/test/java/com/google/firebase/auth/FirebaseUserManagerTest.java

@@ -430,6 +430,52 @@ public void testImportUsersLargeList() {
     }
   }
 
+  @Test
+  public void testListTenants() throws Exception {
+    final TestResponseInterceptor interceptor = initializeAppForUserManagement(
+        TestUtils.loadResource("listTenants.json"));
+    ListTenantsPage page =
+        FirebaseAuth.getInstance().getTenantManager().listTenantsAsync(null, 999).get();
+    ImmutableList<Tenant> tenants = ImmutableList.copyOf(page.getValues());
+    assertEquals(2, tenants.size());
+    checkTenant(tenants.get(0), "TENANT_1");
+    checkTenant(tenants.get(1), "TENANT_2");
+    assertEquals("", page.getNextPageToken());
+    checkRequestHeaders(interceptor);
+
+    GenericUrl url = interceptor.getResponse().getRequest().getUrl();
+    assertEquals(999, url.getFirst("pageSize"));
+    assertNull(url.getFirst("pageToken"));
+  }
+
+  @Test
+  public void testListTenantsWithPageToken() throws Exception {
+    final TestResponseInterceptor interceptor = initializeAppForUserManagement(
+        TestUtils.loadResource("listTenants.json"));
+    ListTenantsPage page =
+        FirebaseAuth.getInstance().getTenantManager().listTenantsAsync("token", 999).get();
+    ImmutableList<Tenant> tenants = ImmutableList.copyOf(page.getValues());
+    assertEquals(2, tenants.size());
+    checkTenant(tenants.get(0), "TENANT_1");
+    checkTenant(tenants.get(1), "TENANT_2");
+    assertEquals("", page.getNextPageToken());
+    checkRequestHeaders(interceptor);
+
+    GenericUrl url = interceptor.getResponse().getRequest().getUrl();
+    assertEquals(999, url.getFirst("pageSize"));
+    assertEquals("token", url.getFirst("pageToken"));
+  }
+
+  @Test
+  public void testListZeroTenants() throws Exception {
+    final TestResponseInterceptor interceptor = initializeAppForUserManagement("{}");
+    ListTenantsPage page =
+        FirebaseAuth.getInstance().getTenantManager().listTenantsAsync(null).get();
+    assertTrue(Iterables.isEmpty(page.getValues()));
+    assertEquals("", page.getNextPageToken());
+    checkRequestHeaders(interceptor);
+  }
+
   @Test
   public void testCreateSessionCookie() throws Exception {
     TestResponseInterceptor interceptor = initializeAppForUserManagement(
@@ -1264,6 +1310,13 @@ private static void checkUserRecord(UserRecord userRecord) {
     assertEquals("gold", claims.get("package"));
   }
 
+  private static void checkTenant(Tenant tenant, String tenantId) {
+    assertEquals(tenantId, tenant.getTenantId());
+    assertEquals("DISPLAY_NAME", tenant.getDisplayName());
+    assertTrue(tenant.isPasswordSignInAllowed());
+    assertFalse(tenant.isEmailLinkSignInEnabled());
+  }
+
   private static void checkRequestHeaders(TestResponseInterceptor interceptor) {
     HttpHeaders headers = interceptor.getResponse().getRequest().getHeaders();
     String auth = "Bearer " + TEST_TOKEN;
@@ -1276,5 +1329,5 @@ private static void checkRequestHeaders(TestResponseInterceptor interceptor) {
   private interface UserManagerOp {
     void call(FirebaseAuth auth) throws Exception;
   }
-  
+
 }

src/test/resources/listTenants.json

@@ -0,0 +1,17 @@
+{
+  "tenants" : [ {
+    "name" : "TENANT_1",
+    "displayName" : "DISPLAY_NAME",
+    "allowPasswordSignup" : true,
+    "enableEmailLinkSignin" : false,
+    "disableAuth" : true,
+    "enableAnonymousUser" : false
+  }, {
+    "name" : "TENANT_2",
+    "displayName" : "DISPLAY_NAME",
+    "allowPasswordSignup" : true,
+    "enableEmailLinkSignin" : false,
+    "disableAuth" : true,
+    "enableAnonymousUser" : false
+  } ]
+}