[Remote Config] add useEmulator to Remote Config SDK

firebase-config/api.txt

@@ -37,6 +37,7 @@ package com.google.firebase.remoteconfig {
     method @NonNull public com.google.android.gms.tasks.Task<java.lang.Void> setConfigSettingsAsync(@NonNull com.google.firebase.remoteconfig.FirebaseRemoteConfigSettings);
     method @NonNull public com.google.android.gms.tasks.Task<java.lang.Void> setDefaultsAsync(@NonNull java.util.Map<java.lang.String,java.lang.Object>);
     method @NonNull public com.google.android.gms.tasks.Task<java.lang.Void> setDefaultsAsync(@XmlRes int);
+    method public void useEmulator(@NonNull String, int);
     field public static final boolean DEFAULT_VALUE_FOR_BOOLEAN = false;
     field public static final byte[] DEFAULT_VALUE_FOR_BYTE_ARRAY;
     field public static final double DEFAULT_VALUE_FOR_DOUBLE = 0.0;

firebase-config/src/main/java/com/google/firebase/remoteconfig/FirebaseRemoteConfig.java

@@ -26,6 +26,7 @@
 import com.google.firebase.abt.AbtException;
 import com.google.firebase.abt.FirebaseABTesting;
 import com.google.firebase.concurrent.FirebaseExecutors;
+import com.google.firebase.emulators.EmulatedServiceSettings;
 import com.google.firebase.installations.FirebaseInstallationsApi;
 import com.google.firebase.installations.InstallationTokenResult;
 import com.google.firebase.remoteconfig.internal.ConfigCacheClient;
@@ -571,6 +572,24 @@ public ConfigUpdateListenerRegistration addOnConfigUpdateListener(
     return configRealtimeHandler.addRealtimeConfigUpdateListener(configUpdateListener);
   }
 
+  /**
+   * Modifies this FirebaseRemoteConfig instance to communicate with the Firebase Remote Config
+   * emulator.
+   *
+   * <p>Note: Call this method before using the instance to do any Remote Config operations.
+   *
+   * @param host the emulator host (for example, 10.0.2.2)
+   * @param port the emulator port (for example, 9299)
+   * @exception FirebaseRemoteConfigClientException Thrown when useEmulator is called after a fetch.
+   */
+  public void useEmulator(@NonNull String host, int port) {
+    if (this.frcMetadata.getInfo().getLastFetchStatus() != LAST_FETCH_STATUS_NO_FETCH_YET) {
+      throw new IllegalStateException(
+          "Cannot connect to emulator after a fetch has been made.");
+    }
+    fetchHandler.setEmulatedServiceSettings(new EmulatedServiceSettings(host, port));
+  }
+
   /**
    * Loads all the configs from disk by calling {@link ConfigCacheClient#get} on each cache client.
    *

firebase-config/src/main/java/com/google/firebase/remoteconfig/internal/ConfigFetchHandler.java

@@ -35,6 +35,7 @@
 import com.google.android.gms.tasks.Task;
 import com.google.android.gms.tasks.Tasks;
 import com.google.firebase.analytics.connector.AnalyticsConnector;
+import com.google.firebase.emulators.EmulatedServiceSettings;
 import com.google.firebase.inject.Provider;
 import com.google.firebase.installations.FirebaseInstallationsApi;
 import com.google.firebase.installations.InstallationTokenResult;
@@ -223,6 +224,10 @@ public Task<FetchResponse> fetchNowWithTypeAndAttemptNumber(
                     copyOfCustomHttpHeaders));
   }
 
+  public void setEmulatedServiceSettings(EmulatedServiceSettings emulatedServiceSettings) {
+    frcBackendApiClient.setEmulatedServiceSettings(emulatedServiceSettings);
+  }
+
   /**
    * Fetches from the backend if the fetched configs cache has expired and the client is not
    * currently throttled.

firebase-config/src/main/java/com/google/firebase/remoteconfig/internal/ConfigFetchHttpClient.java

@@ -43,10 +43,12 @@
 import android.os.Build;
 import android.util.Log;
 import androidx.annotation.Keep;
+import androidx.annotation.Nullable;
 import androidx.annotation.VisibleForTesting;
 import androidx.core.content.pm.PackageInfoCompat;
 import com.google.android.gms.common.util.AndroidUtilsLight;
 import com.google.android.gms.common.util.Hex;
+import com.google.firebase.emulators.EmulatedServiceSettings;
 import com.google.firebase.remoteconfig.BuildConfig;
 import com.google.firebase.remoteconfig.FirebaseRemoteConfigClientException;
 import com.google.firebase.remoteconfig.FirebaseRemoteConfigException;
@@ -94,6 +96,7 @@ public class ConfigFetchHttpClient {
   private final String namespace;
   private final long connectTimeoutInSeconds;
   private final long readTimeoutInSeconds;
+  @Nullable private EmulatedServiceSettings emulatedServiceSettings;
 
   /** ISO-8601 UTC timestamp format. */
   private static final String ISO_DATE_PATTERN = "yyyy-MM-dd'T'HH:mm:ss.SSS'Z'";
@@ -127,6 +130,10 @@ public long getReadTimeoutInSeconds() {
     return readTimeoutInSeconds;
   }
 
+  void setEmulatedServiceSettings(EmulatedServiceSettings emulatedServiceSettings) {
+    this.emulatedServiceSettings = emulatedServiceSettings;
+  }
+
   /**
    * A regular expression for the GMP App Id format. The first group (index 1) is the project
    * number.
@@ -243,6 +250,17 @@ private void setUpUrlConnection(
   }
 
   private String getFetchUrl(String projectNumber, String namespace) {
+    if (emulatedServiceSettings != null) {
+      return "http://"
+          + emulatedServiceSettings.getHost()
+          + ":"
+          + emulatedServiceSettings.getPort()
+          + "/v1/projects/"
+          + projectNumber
+          + "/namespaces/"
+          + namespace
+          + ":fetch";
+    }
     return String.format(FETCH_REGEX_URL, projectNumber, namespace);
   }
 

firebase-config/src/test/java/com/google/firebase/remoteconfig/internal/ConfigFetchHttpClientTest.java

@@ -46,6 +46,7 @@
 import com.google.android.gms.common.util.MockClock;
 import com.google.common.base.Charsets;
 import com.google.common.collect.ImmutableMap;
+import com.google.firebase.emulators.EmulatedServiceSettings;
 import com.google.firebase.remoteconfig.BuildConfig;
 import com.google.firebase.remoteconfig.FirebaseRemoteConfigClientException;
 import com.google.firebase.remoteconfig.FirebaseRemoteConfigException;
@@ -85,6 +86,8 @@ public class ConfigFetchHttpClientTest {
       "etag-" + PROJECT_NUMBER + "-" + DEFAULT_NAMESPACE + "-fetch-%d";
   private static final String FIRST_ETAG = String.format(ETAG_FORMAT, 1);
   private static final String SECOND_ETAG = String.format(ETAG_FORMAT, 2);
+  private static final String FETCH_EMULATOR_REGEX_URL =
+      "http://10.0.2.2:9299/v1/projects/%s/namespaces/%s:fetch";
 
   private Context context;
   private ConfigFetchHttpClient configFetchHttpClient;
@@ -144,6 +147,16 @@ public void createHttpURLConnection_returnsHttpURLConnectionWithValidFetchURL()
         .isEqualTo(String.format(FETCH_REGEX_URL, PROJECT_NUMBER, DEFAULT_NAMESPACE));
   }
 
+  @Test
+  public void createHttpURLConnection_withEmulator() throws Exception {
+    configFetchHttpClient.setEmulatedServiceSettings(new EmulatedServiceSettings("10.0.2.2", 9299));
+
+    HttpURLConnection urlConnection = configFetchHttpClient.createHttpURLConnection();
+
+    assertThat(urlConnection.getURL().toString())
+        .isEqualTo(String.format(FETCH_EMULATOR_REGEX_URL, PROJECT_NUMBER, DEFAULT_NAMESPACE));
+  }
+
   @Test
   public void fetch_newValues_responseSet() throws Exception {
     setServerResponseTo(hasChangeResponseBody, SECOND_ETAG);