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

2 files changed, 10 insertions, 9 deletions

diff --git a/Firestore/Example/Tests/Util/FSTHelpers.h b/Firestore/Example/Tests/Util/FSTHelpers.h
index 91ccbcf..4dbf910 100644
--- a/Firestore/Example/Tests/Util/FSTHelpers.h
+++ b/Firestore/Example/Tests/Util/FSTHelpers.h
@@ -16,7 +16,6 @@
 
 #import <Foundation/Foundation.h>
 
-#import "Firestore/Source/API/FIRDocumentReference+Internal.h"
 #import "Firestore/Source/Core/FSTTypes.h"
 #import "Firestore/Source/Model/FSTDocumentDictionary.h"
 #import "Firestore/Source/Model/FSTDocumentKeySet.h"
@@ -33,7 +32,6 @@
 @class FSTPatchMutation;
 @class FSTQuery;
 @class FSTRemoteEvent;
-@class FSTResourceName;
 @class FSTResourcePath;
 @class FSTSetMutation;
 @class FSTSnapshotVersion;
@@ -145,6 +143,8 @@ NSDate *FSTTestDate(int year, int month, int day, int hour, int minute, int seco
  */
 NSData *FSTTestData(int bytes, ...);
 
+// Note that FIRGeoPoint is a model class in addition to an API class, so we put this helper here
+// instead of FSTAPIHelpers.h
 /** Creates a new GeoPoint from the latitude and longitude values */
 FIRGeoPoint *FSTTestGeoPoint(double latitude, double longitude);
 
diff --git a/Firestore/Example/Tests/Util/FSTHelpers.m b/Firestore/Example/Tests/Util/FSTHelpers.m
index f01bddb..f2b3605 100644
--- a/Firestore/Example/Tests/Util/FSTHelpers.m
+++ b/Firestore/Example/Tests/Util/FSTHelpers.m
@@ -24,6 +24,7 @@
 #import "Firestore/Source/Core/FSTSnapshotVersion.h"
 #import "Firestore/Source/Core/FSTTimestamp.h"
 #import "Firestore/Source/Core/FSTView.h"
+#import "Firestore/Source/Core/FSTViewSnapshot.h"
 #import "Firestore/Source/Local/FSTLocalViewChanges.h"
 #import "Firestore/Source/Local/FSTQueryData.h"
 #import "Firestore/Source/Model/FSTDatabaseID.h"
@@ -138,7 +139,7 @@ FSTDocument *FSTTestDoc(NSString *path,
                         FSTTestSnapshotVersion version,
                         NSDictionary<NSString *, id> *data,
                         BOOL hasMutations) {
-  FSTDocumentKey *key = [FSTDocumentKey keyWithPathString:path];
+  FSTDocumentKey *key = FSTTestDocKey(path);
   return [FSTDocument documentWithData:FSTTestObjectValue(data)
                                    key:key
                                version:FSTTestVersion(version)
@@ -146,7 +147,7 @@ FSTDocument *FSTTestDoc(NSString *path,
 }
 
 FSTDeletedDocument *FSTTestDeletedDoc(NSString *path, FSTTestSnapshotVersion version) {
-  FSTDocumentKey *key = [FSTDocumentKey keyWithPathString:path];
+  FSTDocumentKey *key = FSTTestDocKey(path);
   return [FSTDeletedDocument documentWithKey:key version:FSTTestVersion(version)];
 }
 
@@ -214,7 +215,7 @@ FSTSortOrder *FSTTestOrderBy(NSString *field, NSString *direction) {
 }
 
 NSComparator FSTTestDocComparator(NSString *fieldPath) {
-  FSTQuery *query = [[FSTQuery queryWithPath:[FSTResourcePath pathWithSegments:@[ @"docs" ]]]
+  FSTQuery *query = [FSTTestQuery(@"docs")
       queryByAddingSortOrder:[FSTSortOrder sortOrderWithFieldPath:FSTTestFieldPath(fieldPath)
                                                         ascending:YES]];
   return [query comparator];
@@ -229,7 +230,7 @@ FSTDocumentSet *FSTTestDocSet(NSComparator comp, NSArray<FSTDocument *> *docs) {
 }
 
 FSTSetMutation *FSTTestSetMutation(NSString *path, NSDictionary<NSString *, id> *values) {
-  return [[FSTSetMutation alloc] initWithKey:[FSTDocumentKey keyWithPathString:path]
+  return [[FSTSetMutation alloc] initWithKey:FSTTestDocKey(path)
                                        value:FSTTestObjectValue(values)
                                 precondition:[FSTPrecondition none]];
 }
@@ -274,7 +275,7 @@ FSTTransformMutation *FSTTestTransformMutation(NSString *path,
 }
 
 FSTDeleteMutation *FSTTestDeleteMutation(NSString *path) {
-  return [[FSTDeleteMutation alloc] initWithKey:[FSTDocumentKey keyWithPathString:path]
+  return [[FSTDeleteMutation alloc] initWithKey:FSTTestDocKey(path)
                                    precondition:[FSTPrecondition none]];
 }
 
@@ -334,12 +335,12 @@ FSTLocalViewChanges *FSTTestViewChanges(FSTQuery *query,
                                         NSArray<NSString *> *removedKeys) {
   FSTDocumentKeySet *added = [FSTDocumentKeySet keySet];
   for (NSString *keyPath in addedKeys) {
-    FSTDocumentKey *key = [FSTDocumentKey keyWithPathString:keyPath];
+    FSTDocumentKey *key = FSTTestDocKey(keyPath);
     added = [added setByAddingObject:key];
   }
   FSTDocumentKeySet *removed = [FSTDocumentKeySet keySet];
   for (NSString *keyPath in removedKeys) {
-    FSTDocumentKey *key = [FSTDocumentKey keyWithPathString:keyPath];
+    FSTDocumentKey *key = FSTTestDocKey(keyPath);
     removed = [removed setByAddingObject:key];
   }
   return [FSTLocalViewChanges changesForQuery:query addedKeys:added removedKeys:removed];