Generic/UnnecessaryStringConcat: improve code coverage

Also removes `?>` from the end of UnnecessaryStringConcatUnitTest.1.inc
as this token was not relevant for the tests.

src/Standards/Generic/Tests/Strings/UnnecessaryStringConcatUnitTest.1.inc

@@ -18,4 +18,17 @@ $code = '<'.'?php ';
 $string = 'This is a really long string. '
         . 'It is being used for errors. '
         . 'The message is not translated.';
-?>
+
+$shouldBail = 1 + 1;
+
+$shouldNotTrigger = 'My' . /* comment */ 'string';
+$shouldNotTrigger = 'My' /* comment */ . 'string';
+
+// phpcs:set Generic.Strings.UnnecessaryStringConcat allowMultiline true
+$string = 'Multiline strings are allowed '
+        . 'when setting is enabled.';
+// phpcs:set Generic.Strings.UnnecessaryStringConcat allowMultiline false
+
+// phpcs:set Generic.Strings.UnnecessaryStringConcat error false
+$throwWarning = 'My' . 'string';
+// phpcs:set Generic.Strings.UnnecessaryStringConcat error true

src/Standards/Generic/Tests/Strings/UnnecessaryStringConcatUnitTest.2.inc

@@ -0,0 +1,7 @@
+<?php
+
+// Intentional parse error (only empty tokens after T_STRING_CONCAT).
+// This should be the only test in this file.
+// Testing that the sniff is *not* triggered.
+
+$parseError = 'String' .

src/Standards/Generic/Tests/Strings/UnnecessaryStringConcatUnitTest.php

@@ -65,11 +65,21 @@ public function getErrorList($testFile='')
      * The key of the array should represent the line number and the value
      * should represent the number of warnings that should occur on that line.
      *
+     * @param string $testFile The name of the file being tested.
+     *
      * @return array<int, int>
      */
-    public function getWarningList()
+    public function getWarningList($testFile='')
     {
-        return [];
+        switch ($testFile) {
+        case 'UnnecessaryStringConcatUnitTest.1.inc':
+            return [
+                33 => 1,
+            ];
+
+        default:
+            return [];
+        }
 
     }//end getWarningList()