Replace Objective-C assertions with C++ assertions (#1327)

* Migrate FSTFail to HARD_FAIL
* FSTCFail -> HARD_FAIL
* FSTCAssert -> HARD_ASSERT
* FSTAssert -> HARD_ASSERT
* Replace FSTAssert with NSAssert in dead Objective-C code
* Remove FSTAssert.h

9 files changed, 44 insertions, 157 deletions

diff --git a/Firestore/Example/Firestore.xcodeproj/project.pbxproj b/Firestore/Example/Firestore.xcodeproj/project.pbxproj
index 836017b..ca8b598 100644
--- a/Firestore/Example/Firestore.xcodeproj/project.pbxproj
+++ b/Firestore/Example/Firestore.xcodeproj/project.pbxproj
@@ -43,7 +43,6 @@
 		5492E03420213FFC00B64F25 /* FSTMemorySpecTests.mm in Sources */ = {isa = PBXBuildFile; fileRef = 5492E02F20213FFC00B64F25 /* FSTMemorySpecTests.mm */; };
 		5492E03520213FFC00B64F25 /* FSTSpecTests.mm in Sources */ = {isa = PBXBuildFile; fileRef = 5492E03020213FFC00B64F25 /* FSTSpecTests.mm */; };
 		5492E03C2021401F00B64F25 /* XCTestCase+Await.mm in Sources */ = {isa = PBXBuildFile; fileRef = 5492E0372021401E00B64F25 /* XCTestCase+Await.mm */; };
-		5492E03D2021401F00B64F25 /* FSTAssertTests.mm in Sources */ = {isa = PBXBuildFile; fileRef = 5492E0382021401E00B64F25 /* FSTAssertTests.mm */; };
 		5492E03E2021401F00B64F25 /* FSTEventAccumulator.mm in Sources */ = {isa = PBXBuildFile; fileRef = 5492E0392021401F00B64F25 /* FSTEventAccumulator.mm */; };
 		5492E03F2021401F00B64F25 /* FSTHelpers.mm in Sources */ = {isa = PBXBuildFile; fileRef = 5492E03A2021401F00B64F25 /* FSTHelpers.mm */; };
 		5492E041202143E700B64F25 /* FSTEventAccumulator.mm in Sources */ = {isa = PBXBuildFile; fileRef = 5492E0392021401F00B64F25 /* FSTEventAccumulator.mm */; };
@@ -257,7 +256,7 @@
 		3B843E4A1F3930A400548890 /* remote_store_spec_test.json */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.json; path = remote_store_spec_test.json; sourceTree = "<group>"; };
 		3C81DE3772628FE297055662 /* Pods-Firestore_Example_iOS.debug.xcconfig */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = text.xcconfig; name = "Pods-Firestore_Example_iOS.debug.xcconfig"; path = "Pods/Target Support Files/Pods-Firestore_Example_iOS/Pods-Firestore_Example_iOS.debug.xcconfig"; sourceTree = "<group>"; };
 		3F0992A4B83C60841C52E960 /* Pods-Firestore_Example_iOS.release.xcconfig */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = text.xcconfig; name = "Pods-Firestore_Example_iOS.release.xcconfig"; path = "Pods/Target Support Files/Pods-Firestore_Example_iOS/Pods-Firestore_Example_iOS.release.xcconfig"; sourceTree = "<group>"; };
-		444B7AB3F5A2929070CB1363 /* hard_assert_test.cc */ = {isa = PBXFileReference; includeInIndex = 1; path = hard_assert_test.cc; sourceTree = "<group>"; };
+		444B7AB3F5A2929070CB1363 /* hard_assert_test.cc */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = sourcecode.cpp.cpp; path = hard_assert_test.cc; sourceTree = "<group>"; };
 		54131E9620ADE678001DF3FF /* string_format_test.cc */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = string_format_test.cc; sourceTree = "<group>"; };
 		54511E8D209805F8005BD28F /* hashing_test.cc */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = hashing_test.cc; sourceTree = "<group>"; };
 		5467FAFF203E56F8009C9584 /* FIRFirestoreTests.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; path = FIRFirestoreTests.mm; sourceTree = "<group>"; };
@@ -275,7 +274,6 @@
 		5492E02F20213FFC00B64F25 /* FSTMemorySpecTests.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; path = FSTMemorySpecTests.mm; sourceTree = "<group>"; };
 		5492E03020213FFC00B64F25 /* FSTSpecTests.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; path = FSTSpecTests.mm; sourceTree = "<group>"; };
 		5492E0372021401E00B64F25 /* XCTestCase+Await.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; path = "XCTestCase+Await.mm"; sourceTree = "<group>"; };
-		5492E0382021401E00B64F25 /* FSTAssertTests.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; path = FSTAssertTests.mm; sourceTree = "<group>"; };
 		5492E0392021401F00B64F25 /* FSTEventAccumulator.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; path = FSTEventAccumulator.mm; sourceTree = "<group>"; };
 		5492E03A2021401F00B64F25 /* FSTHelpers.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; path = FSTHelpers.mm; sourceTree = "<group>"; };
 		5492E045202154AA00B64F25 /* FIRCollectionReferenceTests.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; path = FIRCollectionReferenceTests.mm; sourceTree = "<group>"; };
@@ -874,7 +872,6 @@
 		DE51B1851F0D48AC0013853F /* Util */ = {
 			isa = PBXGroup;
 			children = (
-				5492E0382021401E00B64F25 /* FSTAssertTests.mm */,
 				7346E61C20325C6900FD6CEF /* FSTDispatchQueueTests.mm */,
 				54E9281C1F33950B00C1953E /* FSTEventAccumulator.h */,
 				5492E0392021401F00B64F25 /* FSTEventAccumulator.mm */,
@@ -1471,7 +1468,6 @@
 				B65D34A9203C995B0076A5E1 /* FIRTimestampTest.m in Sources */,
 				5492E058202154AB00B64F25 /* FSTAPIHelpers.mm in Sources */,
 				DE2EF0851F3D0B6E003D0CDC /* FSTArraySortedDictionaryTests.m in Sources */,
-				5492E03D2021401F00B64F25 /* FSTAssertTests.mm in Sources */,
 				5492E0C82021557E00B64F25 /* FSTDatastoreTests.mm in Sources */,
 				7346E61D20325C6900FD6CEF /* FSTDispatchQueueTests.mm in Sources */,
 				5492E0B92021555100B64F25 /* FSTDocumentKeyTests.mm in Sources */,
diff --git a/Firestore/Example/Tests/Integration/FSTDatastoreTests.mm b/Firestore/Example/Tests/Integration/FSTDatastoreTests.mm
index 920e3c5..e6e1a19 100644
--- a/Firestore/Example/Tests/Integration/FSTDatastoreTests.mm
+++ b/Firestore/Example/Tests/Integration/FSTDatastoreTests.mm
@@ -33,7 +33,6 @@
 #import "Firestore/Source/Remote/FSTDatastore.h"
 #import "Firestore/Source/Remote/FSTRemoteEvent.h"
 #import "Firestore/Source/Remote/FSTRemoteStore.h"
-#import "Firestore/Source/Util/FSTAssert.h"
 #import "Firestore/Source/Util/FSTDispatchQueue.h"
 
 #import "Firestore/Example/Tests/Util/FSTIntegrationTestCase.h"
@@ -42,6 +41,7 @@
 #include "Firestore/core/src/firebase/firestore/core/database_info.h"
 #include "Firestore/core/src/firebase/firestore/model/database_id.h"
 #include "Firestore/core/src/firebase/firestore/model/precondition.h"
+#include "Firestore/core/src/firebase/firestore/util/hard_assert.h"
 #include "Firestore/core/src/firebase/firestore/util/string_apple.h"
 
 namespace util = firebase::firestore::util;
@@ -118,7 +118,7 @@ NS_ASSUME_NONNULL_BEGIN
 }
 
 - (void)rejectFailedWriteWithBatchID:(FSTBatchID)batchID error:(NSError *)error {
-  FSTFail(@"Not implemented");
+  HARD_FAIL("Not implemented");
 }
 
 - (void)applyRemoteEvent:(FSTRemoteEvent *)remoteEvent {
@@ -129,7 +129,7 @@ NS_ASSUME_NONNULL_BEGIN
 }
 
 - (void)rejectListenWithTargetID:(const TargetId)targetID error:(NSError *)error {
-  FSTFail(@"Not implemented");
+  HARD_FAIL("Not implemented");
 }
 
 @end
diff --git a/Firestore/Example/Tests/Integration/FSTStreamTests.mm b/Firestore/Example/Tests/Integration/FSTStreamTests.mm
index 2e5c9b6..b944a93 100644
--- a/Firestore/Example/Tests/Integration/FSTStreamTests.mm
+++ b/Firestore/Example/Tests/Integration/FSTStreamTests.mm
@@ -24,12 +24,12 @@
 #import "Firestore/Example/Tests/Util/FSTIntegrationTestCase.h"
 #import "Firestore/Source/Remote/FSTDatastore.h"
 #import "Firestore/Source/Remote/FSTStream.h"
-#import "Firestore/Source/Util/FSTAssert.h"
 
 #include "Firestore/core/src/firebase/firestore/auth/empty_credentials_provider.h"
 #include "Firestore/core/src/firebase/firestore/core/database_info.h"
 #include "Firestore/core/src/firebase/firestore/model/database_id.h"
 #include "Firestore/core/src/firebase/firestore/model/snapshot_version.h"
+#include "Firestore/core/src/firebase/firestore/util/hard_assert.h"
 #include "Firestore/core/src/firebase/firestore/util/string_apple.h"
 
 namespace util = firebase::firestore::util;
@@ -121,7 +121,7 @@ using firebase::firestore::model::SnapshotVersion;
  * to be called.
  */
 - (void)awaitNotificationFromBlock:(void (^)(void))block {
-  FSTAssert(_expectation == nil, @"Previous expectation still active");
+  HARD_ASSERT(_expectation == nil, "Previous expectation still active");
   XCTestExpectation *expectation =
       [self.testCase expectationWithDescription:@"awaitCallbackInBlock"];
   _expectation = expectation;
diff --git a/Firestore/Example/Tests/SpecTests/FSTMockDatastore.mm b/Firestore/Example/Tests/SpecTests/FSTMockDatastore.mm
index 3c7f46a..63c3d72 100644
--- a/Firestore/Example/Tests/SpecTests/FSTMockDatastore.mm
+++ b/Firestore/Example/Tests/SpecTests/FSTMockDatastore.mm
@@ -21,7 +21,6 @@
 #import "Firestore/Source/Model/FSTMutation.h"
 #import "Firestore/Source/Remote/FSTSerializerBeta.h"
 #import "Firestore/Source/Remote/FSTStream.h"
-#import "Firestore/Source/Util/FSTAssert.h"
 
 #import "Firestore/Example/Tests/Remote/FSTWatchChange+Testing.h"
 
@@ -80,7 +79,7 @@ NS_ASSUME_NONNULL_BEGIN
                      credentials:credentials
                       serializer:serializer];
   if (self) {
-    FSTAssert(datastore, @"Datastore must not be nil");
+    HARD_ASSERT(datastore, "Datastore must not be nil");
     _datastore = datastore;
     _activeTargets = [NSMutableDictionary dictionary];
   }
@@ -90,7 +89,7 @@ NS_ASSUME_NONNULL_BEGIN
 #pragma mark - Overridden FSTWatchStream methods.
 
 - (void)startWithDelegate:(id<FSTWatchStreamDelegate>)delegate {
-  FSTAssert(!self.open, @"Trying to start already started watch stream");
+  HARD_ASSERT(!self.open, "Trying to start already started watch stream");
   self.open = YES;
   self.delegate = delegate;
   [self notifyStreamOpen];
@@ -148,7 +147,7 @@ NS_ASSUME_NONNULL_BEGIN
           // Technically removing an unknown target is valid (e.g. it could race with a
           // server-side removal), but we want to pay extra careful attention in tests
           // that we only remove targets we listened too.
-          FSTFail(@"Removing a non-active target");
+          HARD_FAIL("Removing a non-active target");
         }
         [self.activeTargets removeObjectForKey:targetID];
       }
@@ -204,7 +203,7 @@ NS_ASSUME_NONNULL_BEGIN
                      credentials:credentials
                       serializer:serializer];
   if (self) {
-    FSTAssert(datastore, @"Datastore must not be nil");
+    HARD_ASSERT(datastore, "Datastore must not be nil");
     _datastore = datastore;
     _sentMutations = [NSMutableArray array];
   }
@@ -214,7 +213,7 @@ NS_ASSUME_NONNULL_BEGIN
 #pragma mark - Overridden FSTWriteStream methods.
 
 - (void)startWithDelegate:(id<FSTWriteStreamDelegate>)delegate {
-  FSTAssert(!self.open, @"Trying to start already started write stream");
+  HARD_ASSERT(!self.open, "Trying to start already started write stream");
   self.open = YES;
   [self.sentMutations removeAllObjects];
   self.delegate = delegate;
@@ -258,8 +257,8 @@ NS_ASSUME_NONNULL_BEGIN
  * Returns the next write that was "sent to the backend", failing if there are no queued sent
  */
 - (NSArray<FSTMutation *> *)nextSentWrite {
-  FSTAssert(self.sentMutations.count > 0,
-            @"Writes need to happen before you can call nextSentWrite.");
+  HARD_ASSERT(self.sentMutations.count > 0,
+              "Writes need to happen before you can call nextSentWrite.");
   NSArray<FSTMutation *> *result = [self.sentMutations objectAtIndex:0];
   [self.sentMutations removeObjectAtIndex:0];
   return result;
@@ -292,7 +291,6 @@ NS_ASSUME_NONNULL_BEGIN
 #pragma mark - Overridden FSTDatastore methods.
 
 - (FSTWatchStream *)createWatchStream {
-  // FSTAssert(self.databaseInfo, @"DatabaseInfo must not be nil");
   self.watchStream = [[FSTMockWatchStream alloc]
         initWithDatastore:self
       workerDispatchQueue:self.workerDispatchQueue
@@ -303,7 +301,6 @@ NS_ASSUME_NONNULL_BEGIN
 }
 
 - (FSTWriteStream *)createWriteStream {
-  // FSTAssert(self.databaseInfo, @"DatabaseInfo must not be nil");
   self.writeStream = [[FSTMockWriteStream alloc]
         initWithDatastore:self
       workerDispatchQueue:self.workerDispatchQueue
@@ -314,7 +311,7 @@ NS_ASSUME_NONNULL_BEGIN
 }
 
 - (void)authorizeAndStartRPC:(GRPCProtoCall *)rpc completion:(FSTVoidErrorBlock)completion {
-  FSTFail(@"FSTMockDatastore shouldn't be starting any RPCs.");
+  HARD_FAIL("FSTMockDatastore shouldn't be starting any RPCs.");
 }
 
 #pragma mark - Method exposed for tests to call.
diff --git a/Firestore/Example/Tests/SpecTests/FSTSpecTests.mm b/Firestore/Example/Tests/SpecTests/FSTSpecTests.mm
index 7b10bd4..77010e5 100644
--- a/Firestore/Example/Tests/SpecTests/FSTSpecTests.mm
+++ b/Firestore/Example/Tests/SpecTests/FSTSpecTests.mm
@@ -34,7 +34,6 @@
 #import "Firestore/Source/Model/FSTMutation.h"
 #import "Firestore/Source/Remote/FSTExistenceFilter.h"
 #import "Firestore/Source/Remote/FSTWatchChange.h"
-#import "Firestore/Source/Util/FSTAssert.h"
 #import "Firestore/Source/Util/FSTClasses.h"
 #import "Firestore/Source/Util/FSTDispatchQueue.h"
 
@@ -45,6 +44,7 @@
 #include "Firestore/core/src/firebase/firestore/auth/user.h"
 #include "Firestore/core/src/firebase/firestore/model/document_key.h"
 #include "Firestore/core/src/firebase/firestore/model/snapshot_version.h"
+#include "Firestore/core/src/firebase/firestore/util/hard_assert.h"
 #include "Firestore/core/src/firebase/firestore/util/log.h"
 #include "Firestore/core/src/firebase/firestore/util/string_apple.h"
 #include "Firestore/core/test/firebase/firestore/testutil/testutil.h"
@@ -233,7 +233,7 @@ static NSString *const kNoIOSTag = @"no-ios";
 
 - (void)doWatchEntity:(NSDictionary *)watchEntity snapshot:(NSNumber *_Nullable)watchSnapshot {
   if (watchEntity[@"docs"]) {
-    FSTAssert(!watchEntity[@"doc"], @"Exactly one of |doc| or |docs| needs to be set.");
+    HARD_ASSERT(!watchEntity[@"doc"], "Exactly one of |doc| or |docs| needs to be set.");
     int count = 0;
     NSArray *docs = watchEntity[@"docs"];
     for (NSDictionary *doc in docs) {
@@ -277,13 +277,13 @@ static NSString *const kNoIOSTag = @"no-ios";
                                                         document:nil];
     [self.driver receiveWatchChange:change snapshotVersion:[self parseVersion:watchSnapshot]];
   } else {
-    FSTFail(@"Either key, doc or docs must be set.");
+    HARD_FAIL("Either key, doc or docs must be set.");
   }
 }
 
 - (void)doWatchFilter:(NSArray *)watchFilter snapshot:(NSNumber *_Nullable)watchSnapshot {
   NSArray<NSNumber *> *targets = watchFilter[0];
-  FSTAssert(targets.count == 1, @"ExistenceFilters currently support exactly one target only.");
+  HARD_ASSERT(targets.count == 1, "ExistenceFilters currently support exactly one target only.");
 
   int keyCount = watchFilter.count == 0 ? 0 : (int)watchFilter.count - 1;
 
@@ -308,7 +308,7 @@ static NSString *const kNoIOSTag = @"no-ios";
 
   NSNumber *runBackoffTimer = closeSpec[@"runBackoffTimer"];
   // TODO(b/72313632): Incorporate backoff in iOS Spec Tests.
-  FSTAssert(runBackoffTimer.boolValue, @"iOS Spec Tests don't support backoff.");
+  HARD_ASSERT(runBackoffTimer.boolValue, "iOS Spec Tests don't support backoff.");
 
   [self.driver receiveWatchStreamError:code userInfo:errorSpec];
 }
@@ -323,8 +323,8 @@ static NSString *const kNoIOSTag = @"no-ios";
       [self.driver receiveWriteAckWithVersion:version mutationResults:@[ mutationResult ]];
 
   if (expectUserCallback.boolValue) {
-    FSTAssert(write.done, @"Write should be done");
-    FSTAssert(!write.error, @"Ack should not fail");
+    HARD_ASSERT(write.done, "Write should be done");
+    HARD_ASSERT(!write.error, "Ack should not fail");
   }
 }
 
@@ -336,7 +336,7 @@ static NSString *const kNoIOSTag = @"no-ios";
   FSTOutstandingWrite *write = [self.driver receiveWriteError:code userInfo:errorSpec];
 
   if (expectUserCallback.boolValue) {
-    FSTAssert(write.done, @"Write should be done");
+    HARD_ASSERT(write.done, "Write should be done");
     XCTAssertNotNil(write.error, @"Write should have failed");
     XCTAssertEqualObjects(write.error.domain, FIRFirestoreErrorDomain);
     XCTAssertEqual(write.error.code, code);
@@ -358,7 +358,7 @@ static NSString *const kNoIOSTag = @"no-ios";
   } else if ([timer isEqualToString:@"online_state_timeout"]) {
     timerID = FSTTimerIDOnlineStateTimeout;
   } else {
-    FSTFail(@"runTimer spec step specified unknown timer: %@", timer);
+    HARD_FAIL("runTimer spec step specified unknown timer: %s", timer);
   }
 
   [self.driver runTimer:timerID];
@@ -427,7 +427,7 @@ static NSString *const kNoIOSTag = @"no-ios";
     [self doWatchStreamClose:step[@"watchStreamClose"]];
   } else if (step[@"watchProto"]) {
     // watchProto isn't yet used, and it's unclear how to create arbitrary protos from JSON.
-    FSTFail(@"watchProto is not yet supported.");
+    HARD_FAIL("watchProto is not yet supported.");
   } else if (step[@"writeAck"]) {
     [self doWriteAck:step[@"writeAck"]];
   } else if (step[@"failWrite"]) {
diff --git a/Firestore/Example/Tests/SpecTests/FSTSyncEngineTestDriver.mm b/Firestore/Example/Tests/SpecTests/FSTSyncEngineTestDriver.mm
index 40ebfb9..d346197 100644
--- a/Firestore/Example/Tests/SpecTests/FSTSyncEngineTestDriver.mm
+++ b/Firestore/Example/Tests/SpecTests/FSTSyncEngineTestDriver.mm
@@ -30,7 +30,6 @@
 #import "Firestore/Source/Model/FSTMutation.h"
 #import "Firestore/Source/Remote/FSTDatastore.h"
 #import "Firestore/Source/Remote/FSTWatchChange.h"
-#import "Firestore/Source/Util/FSTAssert.h"
 
 #import "Firestore/Example/Tests/Core/FSTSyncEngine+Testing.h"
 #import "Firestore/Example/Tests/SpecTests/FSTMockDatastore.h"
@@ -40,6 +39,7 @@
 #include "Firestore/core/src/firebase/firestore/core/database_info.h"
 #include "Firestore/core/src/firebase/firestore/model/database_id.h"
 #include "Firestore/core/src/firebase/firestore/model/document_key.h"
+#include "Firestore/core/src/firebase/firestore/util/hard_assert.h"
 #include "Firestore/core/src/firebase/firestore/util/log.h"
 
 using firebase::firestore::auth::EmptyCredentialsProvider;
@@ -183,9 +183,9 @@ NS_ASSUME_NONNULL_BEGIN
 
 - (void)validateUsage {
   // We could relax this if we found a reason to.
-  FSTAssert(self.events.count == 0,
-            @"You must clear all pending events by calling"
-             " capturedEventsSinceLastCall before calling shutdown.");
+  HARD_ASSERT(self.events.count == 0,
+              "You must clear all pending events by calling"
+              " capturedEventsSinceLastCall before calling shutdown.");
 }
 
 - (void)shutdown {
@@ -197,11 +197,11 @@ NS_ASSUME_NONNULL_BEGIN
 - (void)validateNextWriteSent:(FSTMutation *)expectedWrite {
   NSArray<FSTMutation *> *request = [self.datastore nextSentWrite];
   // Make sure the write went through the pipe like we expected it to.
-  FSTAssert(request.count == 1, @"Only single mutation requests are supported at the moment");
+  HARD_ASSERT(request.count == 1, "Only single mutation requests are supported at the moment");
   FSTMutation *actualWrite = request[0];
-  FSTAssert([actualWrite isEqual:expectedWrite],
-            @"Mock datastore received write %@ but first outstanding mutation was %@", actualWrite,
-            expectedWrite);
+  HARD_ASSERT([actualWrite isEqual:expectedWrite],
+              "Mock datastore received write %s but first outstanding mutation was %s", actualWrite,
+              expectedWrite);
   LOG_DEBUG("A write was sent: %s", actualWrite);
 }
 
@@ -347,7 +347,7 @@ NS_ASSUME_NONNULL_BEGIN
     [self.datastore failWatchStreamWithError:error];
     // Unlike web, stream should re-open synchronously (if we have any listeners)
     if (self.queryListeners.count > 0) {
-      FSTAssert(self.datastore.isWatchStreamOpen, @"Watch stream is open");
+      HARD_ASSERT(self.datastore.isWatchStreamOpen, "Watch stream is open");
     }
   }];
 }
diff --git a/Firestore/Example/Tests/Util/FSTAssertTests.mm b/Firestore/Example/Tests/Util/FSTAssertTests.mm
deleted file mode 100644
index 0cba03f..0000000
--- a/Firestore/Example/Tests/Util/FSTAssertTests.mm
+++ /dev/null
@@ -1,105 +0,0 @@
-/*
- * Copyright 2017 Google
- *
- * 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.
- */
-
-#import "Firestore/Source/Util/FSTAssert.h"
-
-#import <XCTest/XCTest.h>
-
-@interface FSTAssertTests : XCTestCase
-@end
-
-@implementation FSTAssertTests
-
-- (void)testFail {
-  @try {
-    [self failingMethod];
-    XCTFail("Should not have succeeded");
-  } @catch (NSException *ex) {
-    XCTAssertEqualObjects(ex.name, NSInternalInconsistencyException);
-    XCTAssertEqualObjects(ex.reason, @"FIRESTORE INTERNAL ASSERTION FAILED: 0:foo:bar");
-  }
-}
-
-// A method guaranteed to fail. Note that the return type is intentionally something that is
-// not actually returned in the body to ensure that the function attribute declarations in the
-// macro properly mark this macro invocation as never returning.
-- (int)failingMethod {
-  FSTFail(@"%d:%s:%@", 0, "foo", @"bar");
-}
-
-- (void)testCFail {
-  @try {
-    failingFunction();
-    XCTFail("Should not have succeeded");
-  } @catch (NSException *ex) {
-    XCTAssertEqualObjects(ex.name, NSInternalInconsistencyException);
-    XCTAssertEqualObjects(ex.reason, @"FIRESTORE INTERNAL ASSERTION FAILED: 0:foo:bar");
-  }
-}
-
-// A function guaranteed to fail. Note that the return type is intentionally something that is
-// not actually returned in the body to ensure that the function attribute declarations in the
-// macro properly mark this macro invocation as never returning.
-int failingFunction() {
-  FSTCFail(@"%d:%s:%@", 0, "foo", @"bar");
-}
-
-- (void)testAssertNonFailing {
-  @try {
-    FSTAssert(YES, @"shouldn't fail");
-  } @catch (NSException *ex) {
-    XCTFail("Should not have failed, but got %@", ex);
-  }
-}
-
-- (void)testAssertFailing {
-  @try {
-    FSTAssert(NO, @"should fail");
-    XCTFail("Should not have succeeded");
-  } @catch (NSException *ex) {
-    XCTAssertEqualObjects(ex.name, NSInternalInconsistencyException);
-    XCTAssertEqualObjects(ex.reason, @"FIRESTORE INTERNAL ASSERTION FAILED: should fail");
-  }
-}
-
-- (void)testCAssertNonFailing {
-  @try {
-    nonAssertingFunction();
-  } @catch (NSException *ex) {
-    XCTFail("Should not have failed, but got %@", ex);
-  }
-}
-
-int nonAssertingFunction() {
-  FSTCAssert(YES, @"shouldn't fail");
-  return 0;
-}
-
-- (void)testCAssertFailing {
-  @try {
-    assertingFunction();
-    XCTFail("Should not have succeeded");
-  } @catch (NSException *ex) {
-    XCTAssertEqualObjects(ex.name, NSInternalInconsistencyException);
-    XCTAssertEqualObjects(ex.reason, @"FIRESTORE INTERNAL ASSERTION FAILED: should fail");
-  }
-}
-
-int assertingFunction() {
-  FSTCAssert(NO, @"should fail");
-}
-
-@end
diff --git a/Firestore/Example/Tests/Util/FSTEventAccumulator.mm b/Firestore/Example/Tests/Util/FSTEventAccumulator.mm
index 3ab6035..835dc68 100644
--- a/Firestore/Example/Tests/Util/FSTEventAccumulator.mm
+++ b/Firestore/Example/Tests/Util/FSTEventAccumulator.mm
@@ -18,12 +18,12 @@
 
 #import <XCTest/XCTest.h>
 
+#import "Firestore/Example/Tests/Util/XCTestCase+Await.h"
 #import "Firestore/Source/Public/FIRDocumentSnapshot.h"
 #import "Firestore/Source/Public/FIRQuerySnapshot.h"
 #import "Firestore/Source/Public/FIRSnapshotMetadata.h"
-#import "Firestore/Source/Util/FSTAssert.h"
 
-#import "Firestore/Example/Tests/Util/XCTestCase+Await.h"
+#include "Firestore/core/src/firebase/firestore/util/hard_assert.h"
 
 NS_ASSUME_NONNULL_BEGIN
 
@@ -54,7 +54,7 @@ NS_ASSUME_NONNULL_BEGIN
 
 - (NSArray<id> *)awaitEvents:(NSUInteger)events name:(NSString *)name {
   @synchronized(self) {
-    FSTAssert(!self.expectation, @"Existing expectation still pending?");
+    HARD_ASSERT(!self.expectation, "Existing expectation still pending?");
     self.expectation = [self.testCase expectationWithDescription:name];
     self.maxEvents = self.maxEvents + events;
     [self checkFulfilled];
@@ -91,7 +91,7 @@ NS_ASSUME_NONNULL_BEGIN
   if ([event isKindOfClass:[FIRDocumentSnapshot class]]) {
     return ((FIRDocumentSnapshot *)event).metadata.hasPendingWrites;
   } else {
-    FSTAssert([event isKindOfClass:[FIRQuerySnapshot class]], @"Unexpected event: %@", event);
+    HARD_ASSERT([event isKindOfClass:[FIRQuerySnapshot class]], "Unexpected event: %s", event);
     return ((FIRQuerySnapshot *)event).metadata.hasPendingWrites;
   }
 }
diff --git a/Firestore/Example/Tests/Util/FSTHelpers.mm b/Firestore/Example/Tests/Util/FSTHelpers.mm
index bc2f005..5ed4fd5 100644
--- a/Firestore/Example/Tests/Util/FSTHelpers.mm
+++ b/Firestore/Example/Tests/Util/FSTHelpers.mm
@@ -40,7 +40,6 @@
 #import "Firestore/Source/Model/FSTMutation.h"
 #import "Firestore/Source/Remote/FSTRemoteEvent.h"
 #import "Firestore/Source/Remote/FSTWatchChange.h"
-#import "Firestore/Source/Util/FSTAssert.h"
 
 #include "Firestore/core/src/firebase/firestore/model/database_id.h"
 #include "Firestore/core/src/firebase/firestore/model/document_key.h"
@@ -140,7 +139,7 @@ FSTFieldValue *FSTTestFieldValue(id _Nullable value) {
 
 FSTObjectValue *FSTTestObjectValue(NSDictionary<NSString *, id> *data) {
   FSTFieldValue *wrapped = FSTTestFieldValue(data);
-  FSTCAssert([wrapped isKindOfClass:[FSTObjectValue class]], @"Unsupported value: %@", data);
+  HARD_ASSERT([wrapped isKindOfClass:[FSTObjectValue class]], "Unsupported value: %s", data);
   return (FSTObjectValue *)wrapped;
 }
 
@@ -195,15 +194,15 @@ id<FSTFilter> FSTTestFilter(const absl::string_view field, NSString *opString, i
   } else if ([opString isEqualToString:@"array_contains"]) {
     op = FSTRelationFilterOperatorArrayContains;
   } else {
-    FSTCFail(@"Unsupported operator type: %@", opString);
+    HARD_FAIL("Unsupported operator type: %s", opString);
   }
 
   FSTFieldValue *data = FSTTestFieldValue(value);
   if ([data isEqual:[FSTDoubleValue nanValue]]) {
-    FSTCAssert(op == FSTRelationFilterOperatorEqual, @"Must use == with NAN.");
+    HARD_ASSERT(op == FSTRelationFilterOperatorEqual, "Must use == with NAN.");
     return [[FSTNanFilter alloc] initWithField:path];
   } else if ([data isEqual:[FSTNullValue nullValue]]) {
-    FSTCAssert(op == FSTRelationFilterOperatorEqual, @"Must use == with Null.");
+    HARD_ASSERT(op == FSTRelationFilterOperatorEqual, "Must use == with Null.");
     return [[FSTNullFilter alloc] initWithField:path];
   } else {
     return [FSTRelationFilter filterWithField:path filterOperator:op value:data];
@@ -218,7 +217,7 @@ FSTSortOrder *FSTTestOrderBy(const absl::string_view field, NSString *direction)
   } else if ([direction isEqualToString:@"desc"]) {
     ascending = NO;
   } else {
-    FSTCFail(@"Unsupported direction: %@", direction);
+    HARD_FAIL("Unsupported direction: %s", direction);
   }
   return [FSTSortOrder sortOrderWithFieldPath:path ascending:ascending];
 }
@@ -272,8 +271,8 @@ FSTTransformMutation *FSTTestTransformMutation(NSString *path, NSDictionary<NSSt
   FSTDocumentKey *key = [FSTDocumentKey keyWithPath:testutil::Resource(util::MakeStringView(path))];
   FSTUserDataConverter *converter = FSTTestUserDataConverter();
   FSTParsedUpdateData *result = [converter parsedUpdateData:data];
-  FSTCAssert(result.data.value.count == 0,
-             @"FSTTestTransformMutation() only expects transforms; no other data");
+  HARD_ASSERT(result.data.value.count == 0,
+              "FSTTestTransformMutation() only expects transforms; no other data");
   return [[FSTTransformMutation alloc] initWithKey:key
                                    fieldTransforms:std::move(result.fieldTransforms)];
 }