Fix a couple small issues I tripped over today. (#2806)

* Fix a couple small issues I tripped over today.

1. Fix primeBackend so it uses an isolated FIRFirestore* instance. I ran into
   an issue where tests that try to change .settings would fail if they were the
   very first test run, since primeBackend had already configured the client and
   so settings could no longer be changed.
2. Remove FIRFirestore.client and make api::Firestore.client() assert client is configured.

Author: mikelehen

Firestore/Example/Tests/Util/FSTIntegrationTestCase.mm

@@ -85,6 +85,7 @@ - (void)setUp {
   [super setUp];
 
   [self clearPersistence];
+  [self primeBackend];
 
   _firestores = [NSMutableArray array];
   self.db = [self firestore];
@@ -202,14 +203,13 @@ - (FIRFirestore *)firestoreWithProjectID:(NSString *)projectID {
 
   [_firestores addObject:firestore];
 
-  [self primeBackend:firestore];
-
   return firestore;
 }
 
-- (void)primeBackend:(FIRFirestore *)db {
+- (void)primeBackend {
   static dispatch_once_t onceToken;
   dispatch_once(&onceToken, ^{
+    FIRFirestore *db = [self firestore];
     XCTestExpectation *watchInitialized =
         [self expectationWithDescription:@"Prime backend: Watch initialized"];
     __block XCTestExpectation *watchUpdateReceived;
@@ -247,6 +247,8 @@ - (void)primeBackend:(FIRFirestore *)db {
                                  }];
 
     [listenerRegistration remove];
+
+    [self shutdownFirestore:db];
   });
 }
 
@@ -393,14 +395,13 @@ - (void)mergeDocumentRef:(FIRDocumentReference *)ref
 }
 
 - (void)disableNetwork {
-  [self.db.client
+  [self.db
       disableNetworkWithCompletion:[self completionForExpectationWithName:@"Disable Network."]];
   [self awaitExpectations];
 }
 
 - (void)enableNetwork {
-  [self.db.client
-      enableNetworkWithCompletion:[self completionForExpectationWithName:@"Enable Network."]];
+  [self.db enableNetworkWithCompletion:[self completionForExpectationWithName:@"Enable Network."]];
   [self awaitExpectations];
 }
 

Firestore/Source/API/FIRFirestore+Internal.h

@@ -68,7 +68,6 @@ NS_ASSUME_NONNULL_BEGIN
 
 // FIRFirestore ownes the DatabaseId instance.
 @property(nonatomic, assign, readonly) const firebase::firestore::model::DatabaseId *databaseID;
-@property(nonatomic, strong, readonly) FSTFirestoreClient *client;
 @property(nonatomic, strong, readonly) FSTUserDataConverter *dataConverter;
 
 @end

Firestore/Source/API/FIRFirestore.mm

@@ -174,13 +174,6 @@ - (void)setSettings:(FIRFirestoreSettings *)settings {
   _firestore->set_settings(settings);
 }
 
-/**
- * Ensures that the FirestoreClient is configured and returns it.
- */
-- (FSTFirestoreClient *)client {
-  return _firestore->client();
-}
-
 - (FIRCollectionReference *)collectionWithPath:(NSString *)collectionPath {
   if (!collectionPath) {
     ThrowInvalidArgument("Collection path cannot be nil.");

Firestore/Source/API/FIRQuery.mm

@@ -121,7 +121,7 @@ - (void)getDocumentsWithSource:(FIRFirestoreSource)publicSource
                                          NSError *_Nullable error))completion {
   Source source = MakeSource(publicSource);
   if (source == Source::Cache) {
-    [self.firestore.client getDocumentsFromLocalCache:self completion:completion];
+    [self.firestore.wrapped->client() getDocumentsFromLocalCache:self completion:completion];
     return;
   }
 

Firestore/Source/API/FIRWriteBatch.mm

@@ -133,7 +133,7 @@ - (void)commit {
 - (void)commitWithCompletion:(nullable void (^)(NSError *_Nullable error))completion {
   [self verifyNotCommitted];
   self.committed = TRUE;
-  [self.firestore.client writeMutations:std::move(_mutations) completion:completion];
+  [self.firestore.wrapped->client() writeMutations:std::move(_mutations) completion:completion];
 }
 
 - (void)verifyNotCommitted {

Firestore/core/src/firebase/firestore/api/firestore.h

@@ -32,6 +32,7 @@
 #include "Firestore/core/src/firebase/firestore/auth/credentials_provider.h"
 #include "Firestore/core/src/firebase/firestore/model/database_id.h"
 #include "Firestore/core/src/firebase/firestore/util/async_queue.h"
+#include "Firestore/core/src/firebase/firestore/util/hard_assert.h"
 
 NS_ASSUME_NONNULL_BEGIN
 
@@ -75,6 +76,7 @@ class Firestore {
   }
 
   FSTFirestoreClient* client() {
+    HARD_ASSERT(client_, "Client is not yet configured.");
     return client_;
   }