Drop SubscriberFormBase email validation, add test

Assigned to me.

I tried something but is not correct...

+    if (!$validation) {
+      $this->setErrorByName('mail[0][value]', t('The e-mail address you supplied is not valid.'));
+    }

First, you should start with this line. The reason you have an error is $this->setErrorByName does not exist

I changed..

I forgot 'Needs review'

+++ b/src/Tests/SimplenewsSubscribeTest.php
@@ -863,4 +863,57 @@ class SimplenewsSubscribeTest extends SimplenewsTestBase {
 
+  function testSubscribeAnonymousWithInvalidEmail() {
+    // 0. Preparation

You should add a dock block here to explain what your method is doing.

Also add visibility before function, "public" should be ok.

+++ b/src/Tests/SimplenewsSubscribeTest.php
@@ -863,4 +863,57 @@ class SimplenewsSubscribeTest extends SimplenewsTestBase {
+      'administer newsletters',
+      'administer permissions')
+    );

Parenthesis should be on a new line here. Should look like this:
'administer newsletters',
'administer permissions',
)

+++ b/src/Tests/SimplenewsSubscribeTest.php
@@ -863,4 +863,57 @@ class SimplenewsSubscribeTest extends SimplenewsTestBase {
+    );
+    $single_block = $this->setupSubscriptionBlock($block_settings);
+

$single_block is not used anywhere after this code. You can remove it.

+++ b/src/Tests/SimplenewsSubscribeTest.php
@@ -863,4 +863,57 @@ class SimplenewsSubscribeTest extends SimplenewsTestBase {
+
+    // Testing invalid email
+    // Testing invalid email

Remove one of these.

+++ b/src/Tests/SimplenewsSubscribeTest.php
@@ -863,4 +863,57 @@ class SimplenewsSubscribeTest extends SimplenewsTestBase {
+    $this->assertText(t("The email address $mail is not valid"), t("Correct"));

This line could be more descriptive. Instead of "Correct" you can say "Invalid email shows error"

With changes..

A separate test just to test invalid mail addresses seems a bit much overhead to me.
I would prefer to extend one of the existing subscription tests with an invalid address and check the message. 2..5 extra lines, not more.

Miro, I took your advice and made changes.

Looks fine now!

Yes, looks good.