Fix StrongPassword validation and refactor it (+readability)

Addresses #48

Sources/Sugar/Validators/StrongPassword.swift

@@ -1,30 +1,47 @@
 import Vapor
 import Validation
 
-private let regex = "^.*(?=.{3,})(?=.*[a-zA-Z])(?=.*[0-9])(?=.*[\\d\\X])(?=.*[^a-zA-Z\\d\\s:]).*$"
-
 /*The password contains characters from at least three of the following four categories:
 
  English uppercase characters (A – Z)
  English lowercase characters (a – z)
  Base 10 digits (0 – 9)
  Non-alphanumeric (For example: !, $, #, or %)
- Unicode characters
+
  */
 
 public struct StrongPassword: Validator {
+
+    static let lowerCaseRegex = "^.*[a-z].*$"
+    static let upperCaseRegex = "^.*[A-Z].*$"
+    static let digitsRegex = "^.*[0-9].*$"
+    static let specialCharRegex = "^.*[^a-zA-Z0-9].*$"
+
+    static let standardRegexes = [lowerCaseRegex, upperCaseRegex, digitsRegex, specialCharRegex]
+
     internal let minLength: Int
+    internal let minMatchingRegexes: Int
+    internal let regexes: [String]
+
+    public init(minLength: Int = 6,
+                regexes: [String] = standardRegexes,
+                minMatchingRegexes: Int = 3) {
 
-    public init(minLength: Int = 6) {
         self.minLength = minLength
+        self.regexes = regexes
+        self.minMatchingRegexes = minMatchingRegexes
     }
 
     public func validate(_ input: String) throws {
+
+        let matchingRegexesCount = regexes
+            .reduce(0, {$0 + ((input.range(of: $1, options: .regularExpression) == nil) ? 0 : 1) })
+
         guard
-            input.range(of: regex, options: .regularExpression) != nil
-            && input.count >= minLength
-        else {
-            throw error("Password is not strong enough. It must be be at least \(minLength) characters long and contain a number, a capital letter and a small letter.")
+            input.count >= minLength,
+            matchingRegexesCount >= minMatchingRegexes
+            else {
+                throw error("Password is not strong enough. It must be be at least \(minLength) characters long and contain a number, a capital letter and a small letter.")
         }
     }
 }

Tests/SugarTests/ValidatorsTests.swift

@@ -21,7 +21,13 @@ class ValidatorsTests: XCTestCase {
         XCTAssertThrowsError(try StrongPassword().validate("p4ssw0rd"))  // Only two categories
         XCTAssertThrowsError(try StrongPassword().validate("Aa1!"))      // Three categories, but too short
         XCTAssertNoThrow(try StrongPassword().validate("p@ssw0rd"))      // Three categories, and long enough
-
+        XCTAssertNoThrow(try StrongPassword().validate("Qwer123"))      // Three categories, and long enough
+        XCTAssertThrowsError(try StrongPassword(minLength: 10).validate("Qwer123"))      // Too short
+        XCTAssertNoThrow(try StrongPassword(minMatchingRegexes: 3).validate("Qwer123"))      // 3/3 should work
+        XCTAssertNoThrow(try StrongPassword(minMatchingRegexes: 2).validate("123_pp"))      // 2/3 should work
+        XCTAssertNoThrow(try StrongPassword(minMatchingRegexes: 1).validate("!234DD"))      // 1/3 should work
+        XCTAssertThrowsError(try StrongPassword(minMatchingRegexes: 4).validate("werQ1c"))  // 4/3 should not work
+        XCTAssertThrowsError(try StrongPassword(regexes: [StrongPassword.specialCharRegex], minMatchingRegexes: 4).validate("aA1🔥🔥🔥"))  // Emoji as special char
     }
 
     func testThatURLValidatorWorks() {