minor symfony#38235 [Yaml] simplify the test (xabbuh)

This PR was merged into the 3.4 branch.

Discussion
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[Yaml] simplify the test

| Q             | A
| ------------- | ---
| Branch?       | 3.4
| Bug fix?      | no
| New feature?  | no
| Deprecations? | no
| Tickets       | symfony#38228 (comment)
| License       | MIT
| Doc PR        |

Commits
-------

bb64fc9 [Yaml] simplify the test

Author: xabbuh

src/Symfony/Component/Yaml/Tests/ParserTest.php

@@ -2381,19 +2381,13 @@ public function testParsingMultipleDocuments()
 c: d
 YAML;
 
-        $expected = ['a' => ['b' => "row\nrow2\n"], 'c' => 'd'];
-
-        // The parser was not used before, so there is a new line after row2
-        $this->assertSame($expected, $this->parser->parse($longDocument));
-
-        $parser = new Parser();
         // The first parsing set and fixed the totalNumberOfLines in the Parser before, so parsing the short document here
         // to reproduce the issue. If the issue would not have been fixed, the next assertion will fail
-        $parser->parse($shortDocument);
+        $this->parser->parse($shortDocument);
 
-        // After the total number of lines has been rset the result will be the same as if a new parser was used
+        // After the total number of lines has been reset the result will be the same as if a new parser was used
         // (before, there was no \n after row2)
-        $this->assertSame($expected, $parser->parse($longDocument));
+        $this->assertSame(['a' => ['b' => "row\nrow2\n"], 'c' => 'd'], $this->parser->parse($longDocument));
     }
 }