Changed ref code sanitzation to use regex.

BraveShared/Analytics/UserReferralProgram.swift

@@ -194,28 +194,16 @@ public class UserReferralProgram {
     /// Uses very strict matching.
     /// Returns the sanitized code, or nil if no code was found
     public class func sanitize(input: String?) -> String? {
-        guard var code = input, code.hasPrefix(self.clipboardPrefix) else { return nil }
+        guard var input = input, input.hasPrefix(self.clipboardPrefix) else { return nil }
 
         // +1 to strip off `:` that proceeds the defined prefix
-        code.removeFirst(self.clipboardPrefix.count + 1)
+        input.removeFirst(self.clipboardPrefix.count + 1)
         // Add any other potential validation here, e.g. validating the actual ref code string
         
-        if code.count != 6 { return nil }
-        let letters = code.prefix(3)
-        let numbers = code.suffix(3)
-
-        // Cannot use `isLetters` or `isUppercase` b/inc Æ and the like
-        let validLetters = letters.allSatisfy(("A"..."Z").contains)
-
-        // Cannot use `isNumber` b/inc 万 and the like
-        let validNumbers = numbers.allSatisfy(("0"..."9").contains)
-
-        // Both conditions must be met
-        return validLetters && validNumbers ? code : nil
-
-        // Regex solution
-//        let valid = code.range(of: #"\b[A-Z]{3}[0-9]{3}\b"#, options: .regularExpression) != nil // true
+        let valid = input.range(of: #"\b[A-Z]{3}[0-9]{3}\b"#, options: .regularExpression) != nil // true
 
+        // Both conditions must be met
+        return valid ? input : nil
     }
 
     /// Same as `customHeaders` only blocking on result, to gaurantee data is available

ClientTests/UserReferralProgramTests.swift

@@ -0,0 +1,30 @@
+// Copyright 2020 The Brave Authors. All rights reserved.
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import XCTest
+
+class UserReferralProgramTests: XCTestCase {
+
+    override func setUpWithError() throws {
+        // Put setup code here. This method is called before the invocation of each test method in the class.
+    }
+
+    override func tearDownWithError() throws {
+        // Put teardown code here. This method is called after the invocation of each test method in the class.
+    }
+
+    func testExample() throws {
+        // This is an example of a functional test case.
+        // Use XCTAssert and related functions to verify your tests produce the correct results.
+    }
+
+    func testPerformanceExample() throws {
+        // This is an example of a performance test case.
+        self.measure {
+            // Put the code you want to measure the time of here.
+        }
+    }
+
+}