minor symfony#25907 Improve assertions (carusogabriel)

This PR was merged into the 2.7 branch.

Discussion
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Improve assertions

| Q             | A
| ------------- | ---
| Branch?       | 2.7
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| License       | MIT
| Doc PR        | -

Following symfony#25420 before start other branches.

Btw, the other branches are 2.8, 3.3, 3.4, 4.0 and master?

Commits
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3d90a22 Improve assertions

Author: fabpot

src/Symfony/Component/Finder/Tests/FinderTest.php

@@ -12,7 +12,6 @@
 namespace Symfony\Component\Finder\Tests;
 
 use Symfony\Component\Finder\Adapter\AdapterInterface;
-use Symfony\Component\Finder\Adapter\GnuFindAdapter;
 use Symfony\Component\Finder\Adapter\PhpAdapter;
 use Symfony\Component\Finder\Finder;
 
@@ -610,15 +609,15 @@ public function testAdapterSelection()
     {
         // test that by default, PhpAdapter is selected
         $adapters = Finder::create()->getAdapters();
-        $this->assertTrue($adapters[0] instanceof PhpAdapter);
+        $this->assertInstanceOf('Symfony\Component\Finder\Adapter\PhpAdapter', $adapters[0]);
 
         // test another adapter selection
         $adapters = Finder::create()->setAdapter('gnu_find')->getAdapters();
-        $this->assertTrue($adapters[0] instanceof GnuFindAdapter);
+        $this->assertInstanceOf('Symfony\Component\Finder\Adapter\GnuFindAdapter', $adapters[0]);
 
         // test that useBestAdapter method removes selection
         $adapters = Finder::create()->useBestAdapter()->getAdapters();
-        $this->assertFalse($adapters[0] instanceof PhpAdapter);
+        $this->assertNotInstanceOf('Symfony\Component\Finder\Adapter\PhpAdapter', $adapters[0]);
     }
 
     public function getTestPathData()