Merge pull request #65 from fredeil/copilot/add-unit-tests

Add unit tests for email validation edge cases

Author: fredeil

test/email_validator_test.dart

@@ -136,4 +136,231 @@ void main() {
           reason: 'E-mail: ' + actual);
     }
   });
+
+  test('Validate empty and whitespace-only input is invalid', () {
+    expect(EmailValidator.validate(''), equals(false));
+    expect(EmailValidator.validate(' '), equals(false));
+    expect(EmailValidator.validate('\t'), equals(false));
+  });
+
+  test('Validate default parameter values', () {
+    // Default: allowTopLevelDomains = false, allowInternational = true
+    expect(EmailValidator.validate('user@example.com'), equals(true),
+        reason: 'Standard email with defaults should be valid');
+    expect(EmailValidator.validate('user@example'), equals(false),
+        reason: 'Top-level domain should be rejected by default');
+    expect(EmailValidator.validate('伊昭傑@郵件.商務'), equals(true),
+        reason: 'International email should be valid by default');
+  });
+
+  test('Validate allowTopLevelDomains parameter', () {
+    expect(EmailValidator.validate('admin@mailserver', false), equals(false),
+        reason:
+            'TLD-only address should be invalid when allowTopLevelDomains is false');
+    expect(EmailValidator.validate('admin@mailserver', true), equals(true),
+        reason:
+            'TLD-only address should be valid when allowTopLevelDomains is true');
+    expect(EmailValidator.validate('user@example', true), equals(true),
+        reason:
+            'Single-label domain should be valid when allowTopLevelDomains is true');
+  });
+
+  test('Validate allowInternational parameter rejects non-ASCII when false',
+      () {
+    expect(EmailValidator.validate('伊昭傑@郵件.商務', false, false), equals(false),
+        reason:
+            'International email should be invalid when allowInternational is false');
+    expect(
+        EmailValidator.validate('user@example.com', false, false), equals(true),
+        reason: 'ASCII email should be valid regardless of allowInternational');
+  });
+
+  test('Validate local-part length boundary', () {
+    final local64 = 'a' * 64;
+    final local65 = 'a' * 65;
+    expect(EmailValidator.validate('$local64@x.org'), equals(true),
+        reason: '64-character local-part should be valid');
+    expect(EmailValidator.validate('$local65@x.org'), equals(false),
+        reason: '65-character local-part should be invalid');
+  });
+
+  test('Validate total email length boundary', () {
+    // The validator rejects emails with length >= 255, so 254 is max valid
+    const valid254 =
+        'the-total-length@of-an-entire-address.cannot-be-longer-than-two-hundred-and-fifty-four-characters.and-this-address-is-254-characters-exactly.so-it-should-be-valid.and-im-going-to-add-some-more-words-here.to-increase-the-length-blah-blah-blah-blah-bla.org';
+    const invalid255 =
+        'the-total-length@of-an-entire-address.cannot-be-longer-than-two-hundred-and-fifty-four-characters.and-this-address-is-255-characters-exactly.so-it-should-be-invalid.and-im-going-to-add-some-more-words-here.to-increase-the-lenght-blah-blah-blah-blah-bl.org';
+    expect(valid254.length, equals(254));
+    expect(EmailValidator.validate(valid254), equals(true),
+        reason: '254-character email should be valid');
+    expect(invalid255.length, equals(255));
+    expect(EmailValidator.validate(invalid255), equals(false),
+        reason: '255-character email should be invalid');
+  });
+
+  test('Validate domain label length boundary', () {
+    expect(
+        EmailValidator.validate(
+            'the-character-limit@for-each-part.of-the-domain.is-sixty-three-characters.this-is-exactly-sixty-three-characters-so-it-is-valid-blah-blah.com'),
+        equals(true),
+        reason: '63-character domain label should be valid');
+    expect(
+        EmailValidator.validate(
+            'the-character-limit@for-each-part.of-the-domain.is-sixty-three-characters.this-is-exactly-sixty-four-characters-so-it-is-invalid-blah-blah.com'),
+        equals(false),
+        reason: '64-character domain label should be invalid');
+  });
+
+  test('Validate domain starting or ending with hyphen is invalid', () {
+    expect(EmailValidator.validate('user@-example.com'), equals(false),
+        reason: 'Domain starting with hyphen should be invalid');
+    expect(EmailValidator.validate('user@example-.com'), equals(false),
+        reason: 'Domain label ending with hyphen should be invalid');
+  });
+
+  test('Validate double hyphens within domain are valid', () {
+    expect(EmailValidator.validate('user@a--b.com'), equals(true),
+        reason: 'Double hyphens within a domain label should be valid');
+  });
+
+  test('Validate numeric-only TLD is invalid', () {
+    expect(EmailValidator.validate('user@example.123'), equals(false),
+        reason: 'Numeric-only TLD should be invalid');
+    expect(EmailValidator.validate('user@123', true), equals(false),
+        reason: 'Numeric-only single-label domain should be invalid');
+  });
+
+  test('Validate domain with leading dot or trailing dot is invalid', () {
+    expect(EmailValidator.validate('user@.com'), equals(false),
+        reason: 'Domain with leading dot should be invalid');
+    expect(EmailValidator.validate('user@com.'), equals(false),
+        reason: 'Domain with trailing dot should be invalid');
+  });
+
+  test('Validate multiple subdomains are valid', () {
+    expect(EmailValidator.validate('user@sub.domain.example.com'), equals(true),
+        reason: 'Multiple subdomains should be valid');
+    expect(EmailValidator.validate('user@a.b.c.d.e.com'), equals(true),
+        reason: 'Many subdomain levels should be valid');
+    expect(EmailValidator.validate('user@example.co.uk'), equals(true),
+        reason: 'Country code TLD with SLD should be valid');
+  });
+
+  test('Validate local-part with dots', () {
+    expect(EmailValidator.validate('.user@example.com'), equals(false),
+        reason: 'Local-part starting with dot should be invalid');
+    expect(EmailValidator.validate('user.@example.com'), equals(false),
+        reason: 'Local-part ending with dot should be invalid');
+    expect(EmailValidator.validate('user..name@example.com'), equals(false),
+        reason: 'Consecutive dots in local-part should be invalid');
+    expect(EmailValidator.validate('user.name@example.com'), equals(true),
+        reason: 'Single dot in local-part should be valid');
+  });
+
+  test('Validate missing local-part or domain is invalid', () {
+    expect(EmailValidator.validate('@example.com'), equals(false),
+        reason: 'Missing local-part should be invalid');
+    expect(EmailValidator.validate('user@'), equals(false),
+        reason: 'Missing domain should be invalid');
+    expect(EmailValidator.validate('@'), equals(false),
+        reason: 'Only @ sign should be invalid');
+  });
+
+  test('Validate multiple @ signs is invalid', () {
+    expect(EmailValidator.validate('user@@example.com'), equals(false),
+        reason: 'Double @ should be invalid');
+  });
+
+  test('Validate spaces in email are invalid', () {
+    expect(EmailValidator.validate('user name@example.com'), equals(false),
+        reason: 'Space in local-part should be invalid');
+    expect(EmailValidator.validate('user@exam ple.com'), equals(false),
+        reason: 'Space in domain should be invalid');
+  });
+
+  test('Validate special characters in local-part', () {
+    expect(EmailValidator.validate('user+tag@example.com'), equals(true),
+        reason: 'Plus sign in local-part should be valid');
+    expect(EmailValidator.validate('user+tag+tag2@example.com'), equals(true),
+        reason: 'Multiple plus signs in local-part should be valid');
+  });
+
+  test('Validate quoted strings edge cases', () {
+    expect(EmailValidator.validate('"test"@example.com', true), equals(true),
+        reason: 'Quoted local-part should be valid');
+    expect(EmailValidator.validate('""@example.com', true), equals(true),
+        reason: 'Empty quoted local-part should be valid');
+    expect(EmailValidator.validate('"@"@example.com', true), equals(true),
+        reason: 'Quoted @ sign in local-part should be valid');
+    expect(EmailValidator.validate('"unclosed@example.com', true), equals(false),
+        reason: 'Unclosed quote should be invalid');
+  });
+
+  test('Validate IPv4 literal edge cases', () {
+    expect(EmailValidator.validate('user@[255.255.255.255]'), equals(true),
+        reason: 'Max octets IPv4 should be valid');
+    expect(EmailValidator.validate('user@[256.0.0.0]'), equals(false),
+        reason: 'IPv4 octet > 255 should be invalid');
+    expect(EmailValidator.validate('user@[1.2.3]'), equals(false),
+        reason: 'IPv4 with only 3 octets should be invalid');
+    expect(EmailValidator.validate('user@[1.2.3.4.5]'), equals(false),
+        reason: 'IPv4 with 5 octets should be invalid');
+    expect(EmailValidator.validate('user@[1.2.3.]'), equals(false),
+        reason: 'IPv4 with trailing dot should be invalid');
+  });
+
+  test('Validate IPv6 literal edge cases', () {
+    expect(EmailValidator.validate('user@[IPv6:::1]'), equals(true),
+        reason: 'IPv6 loopback should be valid');
+    expect(EmailValidator.validate('user@[IPv6:1::1]'), equals(true),
+        reason: 'IPv6 compact form should be valid');
+    expect(EmailValidator.validate('user@[IPv6:1:2:3:4:5:6:7:8]'), equals(true),
+        reason: 'IPv6 full form should be valid');
+    expect(
+        EmailValidator.validate('user@[IPv6:1:2:3:4:5:6:7:8:9]'), equals(false),
+        reason: 'IPv6 with too many groups should be invalid');
+  });
+
+  test('Validate IPv6v4 literal edge cases', () {
+    expect(
+        EmailValidator.validate(
+            'user@[IPv6:aaaa:aaaa:aaaa:aaaa:aaaa:aaaa:127.0.0.1]'),
+        equals(true),
+        reason: 'Valid IPv6v4 address should be valid');
+    expect(
+        EmailValidator.validate(
+            'user@[IPv6:aaaa:aaaa:aaaa:aaaa:aaaa:aaaa:256.0.0.0]'),
+        equals(false),
+        reason: 'IPv6v4 with invalid IPv4 part should be invalid');
+  });
+
+  test('Validate unbracketed IP domain is invalid', () {
+    expect(EmailValidator.validate('user@123.123.123.123'), equals(false),
+        reason:
+            'Unbracketed IP should be treated as numeric domain and be invalid');
+  });
+
+  test('Validate underscore in domain is invalid', () {
+    expect(EmailValidator.validate('user@exam_ple.com'), equals(false),
+        reason: 'Underscore in domain should be invalid');
+  });
+
+  test('Validate single-character TLD is invalid', () {
+    expect(EmailValidator.validate('a@b.c'), equals(false),
+        reason: 'Single-character TLD should be invalid');
+  });
+
+  test('Validate minimal valid email addresses', () {
+    expect(EmailValidator.validate('a@b.cc'), equals(true),
+        reason: 'Minimal valid email should pass');
+    expect(EmailValidator.validate('a@bb.cc'), equals(true),
+        reason: 'Minimal email with 2-char SLD should pass');
+  });
+
+  test('Validate domain with numeric subdomain and alpha TLD', () {
+    expect(EmailValidator.validate('user@123.com'), equals(true),
+        reason: 'Numeric subdomain with alphabetic TLD should be valid');
+    expect(EmailValidator.validate('user@123abc.com'), equals(true),
+        reason: 'Alphanumeric subdomain should be valid');
+  });
 }