Smaller changes before merging

+ changed `getInputFile` to `getInputFiles`
+ added `clearInputFiles` to reset input file list
+ added test for `clearInputFiles`
+ small tweaks on `testInputFiles`

Author: DaanDeSmedt

src/PHPGhostscript/Ghostscript.php

@@ -342,11 +342,21 @@ public function setInputFile($file) : Ghostscript
      *
      * @return array
      */
-    public function getInputFile() : array
+    public function getInputFiles() : array
     {
         return $this->files;
     }
 
+    /**
+     * Clear inputfiles
+     *
+     * @return self
+     */
+    public function clearInputFiles() : Ghostscript
+    {
+        $this->files = [];
+        return $this;
+    }
 
     /**
      * Set output file

tests/PHPGhostscript/PHPGhostscriptTest.php

@@ -94,7 +94,9 @@ public function testInputFile()
     {
         $ghostscript = new Ghostscript();
         $ghostscript->setInputFile(__DIR__ . DIRECTORY_SEPARATOR . 'assets' . DIRECTORY_SEPARATOR . 'Helicopter.ps');
-        $this->assertEquals([__DIR__ . DIRECTORY_SEPARATOR . 'assets' . DIRECTORY_SEPARATOR . 'Helicopter.ps'], $ghostscript->getInputFile());
+        $this->assertEquals([__DIR__ . DIRECTORY_SEPARATOR . 'assets' . DIRECTORY_SEPARATOR . 'Helicopter.ps'], $ghostscript->getInputFiles());
+        $ghostscript->setInputFile(__DIR__ . DIRECTORY_SEPARATOR . 'assets' . DIRECTORY_SEPARATOR . 'Helicopter.ps');
+        $this->assertEquals([__DIR__ . DIRECTORY_SEPARATOR . 'assets' . DIRECTORY_SEPARATOR . 'Helicopter.ps', __DIR__ . DIRECTORY_SEPARATOR . 'assets' . DIRECTORY_SEPARATOR . 'Helicopter.ps'], $ghostscript->getInputFiles());
     }
 
     public function testOutputFile()
@@ -168,4 +170,14 @@ public function testMerging()
         $this->assertEquals("application/pdf", mime_content_type($outputFile));
         $this->assertTrue($result);
     }
+
+    public function testClearInputFiles()
+    {
+        $ghostscript = new Ghostscript();
+        $ghostscript->setInputFile(__DIR__ . DIRECTORY_SEPARATOR . 'assets' . DIRECTORY_SEPARATOR . 'Helicopter.ps');
+        $this->assertEquals([__DIR__ . DIRECTORY_SEPARATOR . 'assets' . DIRECTORY_SEPARATOR . 'Helicopter.ps'], $ghostscript->getInputFiles());
+        $ghostscript->clearInputFiles();
+        $this->assertEquals([], $ghostscript->getInputFiles());
+    }
+
 }