feat: add dedicated test cases to ensure copy and move methods to alw…

…ays overwrite target

InMemoryFilesystemAdapter.php

@@ -223,12 +223,14 @@ public function move(string $source, string $destination, Config $config): void
         $sourcePath = $this->preparePath($source);
         $destinationPath = $this->preparePath($destination);
 
-        if ( ! $this->fileExists($source) || $this->fileExists($destination)) {
+        if ( ! $this->fileExists($source)) {
             throw UnableToMoveFile::fromLocationTo($source, $destination);
         }
 
-        $this->files[$destinationPath] = $this->files[$sourcePath];
-        unset($this->files[$sourcePath]);
+        if ($sourcePath !== $destinationPath) {
+            $this->files[$destinationPath] = $this->files[$sourcePath];
+            unset($this->files[$sourcePath]);
+        }
 
         if ($visibility = $config->get(Config::OPTION_VISIBILITY)) {
             $this->setVisibility($destination, $visibility);

InMemoryFilesystemAdapterTest.php

@@ -190,18 +190,6 @@ public function moving_a_file_successfully(): void
         $this->assertTrue($adapter->fileExists('new-path.txt'));
     }
 
-    /**
-     * @test
-     */
-    public function moving_a_file_with_collision(): void
-    {
-        $this->expectException(UnableToMoveFile::class);
-        $adapter = $this->adapter();
-        $adapter->write('path.txt', 'contents', new Config());
-        $adapter->write('new-path.txt', 'contents', new Config());
-        $adapter->move('path.txt', 'new-path.txt', new Config());
-    }
-
     /**
      * @test
      */