update timestamp

Author: DellaBitta

packages/firestore/src/lite-api/timestamp.ts

@@ -16,6 +16,9 @@
  */
 
 import { Code, FirestoreError } from '../util/error';
+// API extractor fails importing 'property' unless we also explicitly import 'Property'.
+// eslint-disable-next-line @typescript-eslint/no-unused-vars, unused-imports/no-unused-imports-ts
+import { Property, property, validateJSON } from '../util/json_validation';
 import { primitiveComparator } from '../util/misc';
 
 // The earliest date supported by Firestore timestamps (0001-01-01T00:00:00Z).
@@ -174,53 +177,31 @@ export class Timestamp {
     );
   }
 
+  static _jsonSchemaVersion: string = 'firestore/timestamp/1.0';
+  static _jsonSchema = {
+    type: property('string', Timestamp._jsonSchemaVersion),
+    seconds: property('number'),
+    nanoseconds: property('number')
+  };
+
   /** Returns a JSON-serializable representation of this `Timestamp`. */
   toJSON(): { seconds: number; nanoseconds: number; type: string } {
     return {
+      type: Timestamp._jsonSchemaVersion,
       seconds: this.seconds,
-      nanoseconds: this.nanoseconds,
-      type: 'firestore/timestamp/1.0'
+      nanoseconds: this.nanoseconds
     };
   }
 
   /** Builds a `Timestamp` instance from a JSON serialized version of `Bytes`. */
   static fromJSON(json: object): Timestamp {
-    const requiredFields = ['type', 'seconds', 'nanoseconds'];
-    let error: string | undefined = undefined;
-    let seconds: number = 0;
-    let nanoseconds: number = 0;
-    for (const key of requiredFields) {
-      if (!(key in json)) {
-        error = `json missing required field: ${key}`;
-      }
-      // eslint-disable-next-line @typescript-eslint/no-explicit-any
-      const value = (json as any)[key];
-      if (key === 'type') {
-        if (typeof value !== 'string') {
-          error = `json field 'type' must be a string.`;
-          break;
-        } else if (value !== 'firestore/timestamp/1.0') {
-          error = "Expected 'type' field to equal 'firestore/timestamp/1.0'";
-          break;
-        }
-      } else if (key === 'seconds') {
-        if (typeof value !== 'number') {
-          error = `json field 'seconds' must be a number.`;
-          break;
-        }
-        seconds = value;
-      } else {
-        if (typeof value !== 'number') {
-          error = `json field 'nanoseconds' must be a number.`;
-          break;
-        }
-        nanoseconds = value;
-      }
-    }
-    if (error) {
-      throw new FirestoreError(Code.INVALID_ARGUMENT, error);
+    if (validateJSON(json, Timestamp._jsonSchema)) {
+      return new Timestamp(json.seconds, json.nanoseconds);
     }
-    return new Timestamp(seconds, nanoseconds);
+    throw new FirestoreError(
+      Code.INTERNAL,
+      'Unexpected error creating Timestamp from JSON.'
+    );
   }
 
   /**