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, 4 insertions, 4 deletions

diff --git a/Firestore/Example/Tests/SpecTests/FSTSpecTests.m b/Firestore/Example/Tests/SpecTests/FSTSpecTests.m
index 0bd7b43..3abcb48 100644
--- a/Firestore/Example/Tests/SpecTests/FSTSpecTests.m
+++ b/Firestore/Example/Tests/SpecTests/FSTSpecTests.m
@@ -103,11 +103,11 @@ static NSString *const kNoIOSTag = @"no-ios";
 
 - (nullable FSTQuery *)parseQuery:(id)querySpec {
   if ([querySpec isKindOfClass:[NSString class]]) {
-    return [FSTQuery queryWithPath:[FSTResourcePath pathWithString:querySpec]];
+    return FSTTestQuery(querySpec);
   } else if ([querySpec isKindOfClass:[NSDictionary class]]) {
     NSDictionary *queryDict = (NSDictionary *)querySpec;
     NSString *path = queryDict[@"path"];
-    __block FSTQuery *query = [FSTQuery queryWithPath:[FSTResourcePath pathWithString:path]];
+    __block FSTQuery *query = FSTTestQuery(path);
     if (queryDict[@"limit"]) {
       NSNumber *limit = queryDict[@"limit"];
       query = [query queryBySettingLimit:limit.integerValue];
@@ -237,7 +237,7 @@ static NSString *const kNoIOSTag = @"no-ios";
     }
   } else if (watchEntity[@"doc"]) {
     NSArray *docSpec = watchEntity[@"doc"];
-    FSTDocumentKey *key = [FSTDocumentKey keyWithPathString:docSpec[0]];
+    FSTDocumentKey *key = FSTTestDocKey(docSpec[0]);
     FSTObjectValue *value = FSTTestObjectValue(docSpec[2]);
     FSTSnapshotVersion *version = [self parseVersion:docSpec[1]];
     FSTMaybeDocument *doc =
@@ -249,7 +249,7 @@ static NSString *const kNoIOSTag = @"no-ios";
                                                         document:doc];
     [self.driver receiveWatchChange:change snapshotVersion:[self parseVersion:watchSnapshot]];
   } else if (watchEntity[@"key"]) {
-    FSTDocumentKey *docKey = [FSTDocumentKey keyWithPathString:watchEntity[@"key"]];
+    FSTDocumentKey *docKey = FSTTestDocKey(watchEntity[@"key"]);
     FSTWatchChange *change =
         [[FSTDocumentWatchChange alloc] initWithUpdatedTargetIDs:@[]
                                                 removedTargetIDs:watchEntity[@"removedTargets"]