Firestore `isEqual()` on Public Types (#569)

* add bone code for new isEqual and unit test for old isEqual

*   add bone code for `FIRCollectionReference`, `FIRDocumentSnapshot`, `FIRFieldValue`, `FIRQuerySnapshot`, `FIRSnapshotMetadata`;
*   change inconsistenciness of `FIRFieldPath.isEqual` implementation;
*   add unit test (and file) for `FIRDocumentReferenceTest.m`, `FIRFieldPathTest.m`, `FIRQueryTests.testEquals`; `FIRGeoPoint` already has test and Blob is internal type.

* Implement isEqual for FIRCollectionReference

adding the working code and unit test.

* implement isEqual for FIRSnapshotMetadata

* Implement isEqual for FIRDocumentSnapshot

* Implement isEqual for FIRQuerySnapshot

* (un)implement `isEqual` for `FIRFieldValue`

Since `FIRFieldValue` both types are singleton, we do not need override `isEqual`. Add test to test the default `NSObject` `isEqual` works just fine.

* fix style with `scripts/style.sh`

* Implement hash for those with overridden isEqual without hash yet.

* refactor to use test helper functions -- FSTTestFirestore, FSTTestPath, FSTTestDocKey

* refactor using test helper `FSTTestDocSnapshot`, `FSTTestFieldPath`, `FSTTestQuery`, `FSTTestDoc`

* refactoring to use test helper method `FSTTestQuerySnapshot`,

* remove unneccessary nil-check, check isKindOfClass instead of isEqual

* refactoring: adding `FSTAPIHelpers.{h,m}`, `FSTTest{Collection,Document}Ref`,  better naming and style fix

* a file forgot in last commit

* mainly clean up import and some minor refactoring

* fix style via style.sh

* minor style fix

* add pragma ignored -Wnonnull

1 files changed, 1 insertions, 1 deletions

diff --git a/Firestore/Source/Remote/FSTStream.m b/Firestore/Source/Remote/FSTStream.m
index 2c039be..5719ec8 100644
--- a/Firestore/Source/Remote/FSTStream.m
+++ b/Firestore/Source/Remote/FSTStream.m
@@ -542,7 +542,7 @@ static const NSTimeInterval kIdleTimeout = 60.0;
   FSTWeakify(self);
   [self.workerDispatchQueue dispatchAsync:^{
     FSTStrongify(self);
-    if (!self || ![self isStarted]) {
+    if (![self isStarted]) {
       FSTLog(@"%@ Ignoring stream message from inactive stream.", NSStringFromClass([self class]));
     }