add tests for nil

Author: cbaker6

Tests/ParseSwiftTests/ParseObjectTests.swift

@@ -491,6 +491,35 @@ class ParseObjectTests: XCTestCase { // swiftlint:disable:this type_body_length
         XCTAssertEqual(mutableScore.player, score.player)
     }
 
+    func testRevertKeyPathUpdatedNil() throws {
+        var score = GameScore(points: 19, name: "fire")
+        score.objectId = "yolo"
+        var mutableScore = score.mergeable
+        mutableScore.points = 50
+        mutableScore.player = nil
+        XCTAssertNotEqual(mutableScore, score)
+        try mutableScore.revertKeyPath(\.player)
+        XCTAssertNotEqual(mutableScore, score)
+        XCTAssertEqual(mutableScore.objectId, score.objectId)
+        XCTAssertNotEqual(mutableScore.points, score.points)
+        XCTAssertEqual(mutableScore.player, score.player)
+    }
+
+    func testRevertKeyPathOriginalNil() throws {
+        var score = GameScore(points: 19, name: "fire")
+        score.objectId = "yolo"
+        score.player = nil
+        var mutableScore = score.mergeable
+        mutableScore.points = 50
+        mutableScore.player = "ali"
+        XCTAssertNotEqual(mutableScore, score)
+        try mutableScore.revertKeyPath(\.player)
+        XCTAssertNotEqual(mutableScore, score)
+        XCTAssertEqual(mutableScore.objectId, score.objectId)
+        XCTAssertNotEqual(mutableScore.points, score.points)
+        XCTAssertEqual(mutableScore.player, score.player)
+    }
+
     func testRevertKeyPathMissingOriginal() throws {
         var score = GameScore(points: 19, name: "fire")
         score.objectId = "yolo"