refactor(tests): resolves linter warnings

- add /x flag to regular expressions for readability
- initialize local variables upon declaration
- replace die with croak for better error handling
- split long regular expressions into smaller chunks
- use Capture::Tiny for safer output capturing in tests

tests/security-gate.t

@@ -6,44 +6,46 @@ use Test::More;
 use Test::Exception;
 use Test::MockObject;
 use Test::Output;
+use Carp qw(croak);
+use Capture::Tiny qw(capture);
 use Mojo::JSON qw(encode_json);
 
 local $ENV{TEST_MODE} = 1;
 
-my $mock_ua = Test::MockObject -> new();
-$mock_ua -> fake_module('Mojo::UserAgent');
-$mock_ua -> fake_new('Mojo::UserAgent');
+my $mock_ua = Test::MockObject->new();
+$mock_ua->fake_module('Mojo::UserAgent');
+$mock_ua->fake_new('Mojo::UserAgent');
 
 require_ok('../security-gate.pl');
 
 subtest 'Command-line argument parsing' => sub {
     local @ARGV = ();
     stdout_like(
         sub { main() },
-        qr/Security Gate v0\.0\.3/,
+        qr/Security\ Gate\ v0\.0\.3/x,
         'Help message displayed when no arguments provided'
     );
 };
 
 subtest 'Severity counting' => sub {
-    my $mock_response = Test::MockObject -> new();
-    $mock_response -> set_always('code', 200);
-    $mock_response -> set_always('json', [
+    my $mock_response = Test::MockObject->new();
+    $mock_response->set_always('code', 200);
+    $mock_response->set_always('json', [
         { state => 'open', security_vulnerability => { severity => 'high' } },
         { state => 'open', security_vulnerability => { severity => 'critical' } },
         { state => 'open', security_vulnerability => { severity => 'medium' } },
         { state => 'closed', security_vulnerability => { severity => 'low' } },
     ]);
 
-    my $mock_tx = Test::MockObject -> new();
-    $mock_tx -> set_always('result', $mock_response);
+    my $mock_tx = Test::MockObject->new();
+    $mock_tx->set_always('result', $mock_response);
 
-    $mock_ua -> set_always('get', $mock_tx);
+    $mock_ua->set_always('get', $mock_tx);
 
     local @ARGV = ('-t', 'test_token', '-r', 'test_repo');
     stdout_like(
         sub { main() },
-        qr/critical: 1.*high: 1.*medium: 1.*low: 0/s,
+        qr/critical:\ 1.*high:\ 1.*medium:\ 1.*low:\ 0/xs,
         'Severity counts are correct'
     );
 };
@@ -77,22 +79,27 @@ subtest 'Threshold checking' => sub {
 };
 
 subtest 'Output formatting' => sub {
-    my $mock_response = Test::MockObject -> new();
-    $mock_response -> set_always('code', 200);
-    $mock_response -> set_always('json', [
+    my $mock_response = Test::MockObject->new();
+    $mock_response->set_always('code', 200);
+    $mock_response->set_always('json', [
         { state => 'open', security_vulnerability => { severity => 'high' } },
         { state => 'open', security_vulnerability => { severity => 'critical' } },
     ]);
 
-    my $mock_tx = Test::MockObject -> new();
-    $mock_tx -> set_always('result', $mock_response);
+    my $mock_tx = Test::MockObject->new();
+    $mock_tx->set_always('result', $mock_response);
 
-    $mock_ua -> set_always('get', $mock_tx);
+    $mock_ua->set_always('get', $mock_tx);
 
     local @ARGV = ('-t', 'test_token', '-r', 'test_repo');
+
+    my $total_alerts_re = qr/\[!\]\ Total\ of\ security\ alerts:/x;
+    my $critical_alerts_re = qr/\[-\]\ critical:\ 1/x;
+    my $high_alerts_re = qr/\[-\]\ high:\ 1/x;
+
     stdout_like(
         sub { main() },
-        qr/\[!\] Total of security alerts:.*\[-\] critical: 1.*\[-\] high: 1/s,
+        qr/$total_alerts_re.*$critical_alerts_re.*$high_alerts_re/xs,
         'Output is correctly formatted'
     );
 };
@@ -133,37 +140,40 @@ subtest 'Empty response from GitHub API' => sub {
 };
 
 subtest 'Multiple severity thresholds' => sub {
-    my $mock_response = Test::MockObject -> new();
-    $mock_response -> set_always('code', 200);
-    $mock_response -> set_always('json', [
+    my $mock_response = Test::MockObject->new();
+    $mock_response->set_always('code', 200);
+    $mock_response->set_always('json', [
         { state => 'open', security_vulnerability => { severity => 'high' } },
         { state => 'open', security_vulnerability => { severity => 'critical' } },
         { state => 'open', security_vulnerability => { severity => 'medium' } },
     ]);
 
-    my $mock_tx = Test::MockObject -> new();
-    $mock_tx -> set_always('result', $mock_response);
+    my $mock_tx = Test::MockObject->new();
+    $mock_tx->set_always('result', $mock_response);
 
-    $mock_ua -> set_always('get', $mock_tx);
+    $mock_ua->set_always('get', $mock_tx);
 
     local @ARGV = ('-t', 'test_token', '-r', 'test_repo', '-c', '0', '-h', '0', '-m', '0', '-l', '0');
 
-    my $stdout;
-    {
-        local *STDOUT;
-        open STDOUT, '>', \$stdout;
-
-        my $result = main();
-
-        diag("STDOUT: $stdout");
-        diag("Result: $result");
-
-        is(
-            $result,
-            1,
-            'Script exits with non-zero code when multiple thresholds are exceeded'
-        );
-    }
+     my ($stdout, $stderr, $result) = capture {
+        main();
+    };
+
+    diag("STDOUT: $stdout");
+    diag("STDERR: $stderr");
+    diag("Result: $result");
+
+    is(
+        $result,
+        1,
+        'Script exits with non-zero code when multiple thresholds are exceeded'
+    );
+
+    like(
+        $stdout,
+        qr/Total\ of\ security\ alerts:/x,
+        'Output contains expected content'
+    );
 };
 
-done_testing();
+done_testing();