Tests/NullsafeObjectOperatorTest: use named data sets

With non-named data sets, when a test fails, PHPUnit will display the number of the test which failed.

With tests which have a _lot_ of data sets, this makes it _interesting_ (and time-consuming) to debug those, as one now has to figure out which of the data sets in the data provider corresponds to that number.

Using named data sets makes debugging failing tests more straight forward as PHPUnit will display the data set name instead of the number.
Using named data sets also documents what exactly each data set is testing.

Includes minor array normalization.
Include making the data type in the docblock more specific.

Author: jrfnl

tests/Core/Tokenizer/NullsafeObjectOperatorTest.php

@@ -18,7 +18,7 @@ final class NullsafeObjectOperatorTest extends AbstractMethodUnitTest
     /**
      * Tokens to search for.
      *
-     * @var array
+     * @var array<int|string>
      */
     protected $find = [
         T_NULLSAFE_OBJECT_OPERATOR,
@@ -71,13 +71,13 @@ public function testNullsafeObjectOperator($testMarker)
      *
      * @see testNullsafeObjectOperator()
      *
-     * @return array
+     * @return array<string, array<string>>
      */
     public static function dataNullsafeObjectOperator()
     {
         return [
-            ['/* testNullsafeObjectOperator */'],
-            ['/* testNullsafeObjectOperatorWriteContext */'],
+            'nullsafe operator'                         => ['/* testNullsafeObjectOperator */'],
+            'illegal nullsafe operator (write context)' => ['/* testNullsafeObjectOperatorWriteContext */'],
         ];
 
     }//end dataNullsafeObjectOperator()
@@ -117,21 +117,25 @@ public function testTernaryThen($testMarker, $testObjectOperator=false)
      *
      * @see testTernaryThen()
      *
-     * @return array
+     * @return array<string, array<string, string|bool>>
      */
     public static function dataTernaryThen()
     {
         return [
-            ['/* testTernaryThen */'],
-            [
-                '/* testParseErrorWhitespaceNotAllowed */',
-                true,
+            'ternary then'                                         => [
+                'testMarker' => '/* testTernaryThen */',
             ],
-            [
-                '/* testParseErrorCommentNotAllowed */',
-                true,
+            'whitespace between question mark and object operator' => [
+                'testMarker'         => '/* testParseErrorWhitespaceNotAllowed */',
+                'testObjectOperator' => true,
+            ],
+            'comment between question mark and object operator'    => [
+                'testMarker'         => '/* testParseErrorCommentNotAllowed */',
+                'testObjectOperator' => true,
+            ],
+            'parse error/live coding'                              => [
+                'testMarker' => '/* testLiveCoding */',
             ],
-            ['/* testLiveCoding */'],
         ];
 
     }//end dataTernaryThen()