tweak email validation (no functional change)

modules/common/src/main/model.scala

@@ -84,18 +84,11 @@ object EmailAddress {
   private val gmailLikeNormalizedDomains =
     Set("gmail.com", "googlemail.com", "protonmail.com", "protonmail.ch", "pm.me")
 
-  private def hasDotAt(str: String)           = str contains ".@"  // mailgun will reject it
-  private def hasConsecutiveDots(str: String) = str contains ".."  // mailgun will reject it
-  private def startsWithDot(str: String)      = str startsWith "." // mailgun will reject it
-
-  def matches(str: String): Boolean =
-    regex.find(str) &&
-      !hasDotAt(str) &&
-      !hasConsecutiveDots(str) &&
-      !startsWithDot(str)
+  def isValid(str: String) =
+    regex.matches(str) && !str.contains("..") && !str.contains(".@") && !str.startsWith(".")
 
   def from(str: String): Option[EmailAddress] =
-    matches(str) option EmailAddress(str)
+    isValid(str) option EmailAddress(str)
 
   private def isNoReply(str: String) = str.startsWith("noreply.") && str.endsWith("@lichess.org")
 }

modules/common/src/test/EmailTest.scala

@@ -16,4 +16,21 @@ class EmailTest extends Specification {
     }
   }
 
+  "from" should {
+    "accept valid addresses" in {
+      EmailAddress.from("Hello.World+suffix1+suffix2@gmail.com") must beSome
+      EmailAddress.from("kebab-case@example.com") must beSome
+      EmailAddress.from("snake_case@example.com") must beSome
+      EmailAddress.from("_leading.underscore@example.com") must beSome
+      EmailAddress.from("trailing.dash-@example.com") must beSome
+    }
+    "reject invalid addresses" in {
+      EmailAddress.from(".leading.dot@example.com") must beNone
+      EmailAddress.from("trailing.dot.@example.com") must beNone
+      EmailAddress.from("underscore.in@domain_name.com") must beNone
+      EmailAddress.from("consecutive..dots@example.com") must beNone
+      EmailAddress.from("invalid<character@example.com") must beNone
+    }
+  }
+
 }

modules/security/src/main/Signup.scala

@@ -190,7 +190,7 @@ final class Signup(
     } {
       if (
         err.errors.exists(_.messages.contains("error.email_acceptable")) &&
-        err("email").value.exists(EmailAddress.matches)
+        err("email").value.exists(EmailAddress.isValid)
       )
         authLog(username, email, s"Signup with unacceptable email")
     }