replacing Auth by C++ auth implementation (#802)

* lazy replacing FST(Firebase)CredentialsProvider by (Firebase)CredentialsProvider

* lazy replacing FSTUser by User

* adding error-code parameter to TokenListener

* actually use const user& instead of pointer; also add an error util

* add HashUser and pass into the unordered_map

* use User in test

* use c++ CredentialsProvider and subclass in test

* fix unit test

* use explicit capture in lambda instead of capture all by reference

* cache currentUser explicitly when reset sync engineer test driver

* objc object should be captured by value in lambda

* replacing Auth/FSTUser by C++ auth implementation

* address changes

* replacing FSTGetTokenResult by C++ Token implementation

* address changes

* fix unintentional change in merging

* patch the change in objc Auth up-stream

* somehow, the lambda-version of set-user-change-listener does not work... fallback to block

* address changes

* fix another const& v.s. dispatch bug

* fix more const& v.s. dispatch bug  zxu123 committed

* fix a bad sync line

* address changes

* address change

* address change

* fix upstream change from merge

* fix upstream changes

* Suggested fixes for cpp/port_auth (#846)

* Get rid of MockDatastore factory

This avoids the need to statically allocate (and leak) a credentials
provider

* Use absl::make_unique

std::make_unique technically does not exist until C++14.

* #include <utility> for std::move

* Use std::future for the initial user

* fix style

3 files changed, 17 insertions, 10 deletions

diff --git a/Firestore/core/test/firebase/firestore/auth/credentials_provider_test.cc b/Firestore/core/test/firebase/firestore/auth/credentials_provider_test.cc
index 9ae71ba..6895061 100644
--- a/Firestore/core/test/firebase/firestore/auth/credentials_provider_test.cc
+++ b/Firestore/core/test/firebase/firestore/auth/credentials_provider_test.cc
@@ -25,10 +25,11 @@ namespace auth {
 #define UNUSED(x) (void)(x)
 
 TEST(CredentialsProvider, Typedef) {
-  TokenListener token_listener = [](Token token,
-                                    const absl::string_view error) {
+  TokenListener token_listener = [](Token token, const int64_t error_code,
+                                    const absl::string_view error_msg) {
     UNUSED(token);
-    UNUSED(error);
+    UNUSED(error_code);
+    UNUSED(error_msg);
   };
   EXPECT_NE(nullptr, token_listener);
   EXPECT_TRUE(token_listener);
diff --git a/Firestore/core/test/firebase/firestore/auth/empty_credentials_provider_test.cc b/Firestore/core/test/firebase/firestore/auth/empty_credentials_provider_test.cc
index 39012f0..3b487f3 100644
--- a/Firestore/core/test/firebase/firestore/auth/empty_credentials_provider_test.cc
+++ b/Firestore/core/test/firebase/firestore/auth/empty_credentials_provider_test.cc
@@ -25,12 +25,14 @@ namespace auth {
 TEST(EmptyCredentialsProvider, GetToken) {
   EmptyCredentialsProvider credentials_provider;
   credentials_provider.GetToken(
-      /*force_refresh=*/true, [](Token token, const absl::string_view error) {
-        EXPECT_EQ("", token.token());
+      /*force_refresh=*/true, [](Token token, const int64_t error_code,
+                                 const absl::string_view error_msg) {
+        EXPECT_FALSE(token.is_valid());
         const User& user = token.user();
         EXPECT_EQ("", user.uid());
         EXPECT_FALSE(user.is_authenticated());
-        EXPECT_EQ("", error);
+        EXPECT_EQ(FirestoreErrorCode::Ok, error_code);
+        EXPECT_EQ("", error_msg);
       });
 }
 
diff --git a/Firestore/core/test/firebase/firestore/auth/firebase_credentials_provider_test.mm b/Firestore/core/test/firebase/firestore/auth/firebase_credentials_provider_test.mm
index a6ccc4a..3660d53 100644
--- a/Firestore/core/test/firebase/firestore/auth/firebase_credentials_provider_test.mm
+++ b/Firestore/core/test/firebase/firestore/auth/firebase_credentials_provider_test.mm
@@ -42,12 +42,14 @@ TEST(FirebaseCredentialsProviderTest, GetTokenUnauthenticated) {
 
   FirebaseCredentialsProvider credentials_provider(app);
   credentials_provider.GetToken(
-      /*force_refresh=*/true, [](Token token, const absl::string_view error) {
+      /*force_refresh=*/true, [](Token token, const int64_t error_code,
+                                 const absl::string_view error_msg) {
         EXPECT_EQ("", token.token());
         const User& user = token.user();
         EXPECT_EQ("", user.uid());
         EXPECT_FALSE(user.is_authenticated());
-        EXPECT_EQ("", error) << error;
+        EXPECT_EQ(FirestoreErrorCode::Ok, error_code) << error_code;
+        EXPECT_EQ("", error_msg) << error_msg;
       });
 }
 
@@ -56,12 +58,14 @@ TEST(FirebaseCredentialsProviderTest, GetToken) {
 
   FirebaseCredentialsProvider credentials_provider(app);
   credentials_provider.GetToken(
-      /*force_refresh=*/true, [](Token token, const absl::string_view error) {
+      /*force_refresh=*/true, [](Token token, const int64_t error_code,
+                                 const absl::string_view error_msg) {
         EXPECT_EQ("", token.token());
         const User& user = token.user();
         EXPECT_EQ("fake uid", user.uid());
         EXPECT_TRUE(user.is_authenticated());
-        EXPECT_EQ("", error) << error;
+        EXPECT_EQ(FirestoreErrorCode::Ok, error_code) << error_code;
+        EXPECT_EQ("", error_msg) << error_msg;
       });
 }