Set new candidates date when autologging is off

Summary:
During testing, we noticed an edge case where if the app has autologging turned off and then re-enables it, all of a user's transaction history will be logged, which would likely result in over reporting of events. We should assume that these transactions have already been handled and only consider the transactions that occur after the advertiser enables autologging. To achieve this, we set the new candidates date to ```now``` whenever we observe that autologging is turned off. In doing this, we will only consider transactions that have occurred after this date.

This diff implements this functionality.

Reviewed By: jjiang10

Differential Revision: D66309371

fbshipit-source-id: b578b5782e8b4ead3bc58569a3bc3d9c17b1762e

FBSDKCoreKit/FBSDKCoreKit/AppEvents/FBSDKAppEvents.m

@@ -991,6 +991,7 @@ - (void)fetchServerConfiguration:(FBSDKCodeBlock)callback
           }
         }];
       } else {
+        [self.iapTransactionCache setNewCandidatesDate:[NSDate date]];
         [self.iapDedupeProcessor disable];
         [self.paymentObserver stopObservingTransactions];
         [self.transactionObserver stopObserving];

FBSDKCoreKit/FBSDKCoreKit/AppEvents/Internal/IAP/IAPTransactionCache.swift

@@ -130,6 +130,7 @@ extension IAPTransactionCache: _IAPTransactionCaching {
         return
       }
       guard let newValue else {
+        dependencies.dataStore.fb_removeObject(forKey: IAPConstants.newCandidatesDateCacheKey)
         return
       }
       dependencies.dataStore.fb_setObject(newValue, forKey: IAPConstants.newCandidatesDateCacheKey)

FBSDKCoreKit/FBSDKCoreKitTests/Internal/AppEvents/AppEventsTests.swift

@@ -152,7 +152,7 @@ final class AppEventsTests: XCTestCase {
     iapDedupeProcessor = nil
 
     resetTestHelpers()
-
+    IAPTransactionCache.shared.reset()
     super.tearDown()
   }
 
@@ -1797,6 +1797,7 @@ final class AppEventsTests: XCTestCase {
   }
 
   func testFetchingConfigurationStopPaymentObservingIfAutoLogAppEventsDisabled() {
+    let now = Date()
     settings.isAutoLogAppEventsEnabled = false
     let serverConfiguration = ServerConfigurationFixtures.configuration(
       withDictionary: ["implicitPurchaseLoggingEnabled": true]
@@ -1820,6 +1821,11 @@ final class AppEventsTests: XCTestCase {
       transactionObserver.didStopObserving,
       "Fetching a configuration should stop transaction observing if auto log app events is disabled"
     )
+    guard let newCandidatesDate = IAPTransactionCache.shared.newCandidatesDate else {
+      XCTFail("newCandidatesDate should have been set")
+      return
+    }
+    XCTAssertTrue(newCandidatesDate > now)
   }
 
   func testEnablingIAPDedupeShouldEnableIAPDedupe() {
@@ -1883,6 +1889,7 @@ final class AppEventsTests: XCTestCase {
   }
 
   func testEnablingIAPDedupeShouldNotEnableIAPDedupeWhenImplicitPurchaseIsDiabled() {
+    let now = Date()
     settings.isAutoLogAppEventsEnabled = true
     let serverConfiguration = ServerConfigurationFixtures.configuration(
       withDictionary: ["implicitPurchaseLoggingEnabled": 0]
@@ -1895,6 +1902,11 @@ final class AppEventsTests: XCTestCase {
 
     XCTAssertFalse(iapDedupeProcessor.enableWasCalled)
     XCTAssertTrue(iapDedupeProcessor.disableWasCalled)
+    guard let newCandidatesDate = IAPTransactionCache.shared.newCandidatesDate else {
+      XCTFail("newCandidatesDate should have been set")
+      return
+    }
+    XCTAssertTrue(newCandidatesDate > now)
   }
 
   func testFetchingConfigurationIncludingSKAdNetworkIfSKAdNetworkReportEnabled() {