Make sure files exist for our fake assets in tests

tests/Assets/AssetTest.php

@@ -562,6 +562,7 @@ public function it_checks_if_an_extension_matches()
     public function it_gets_the_extension_guessed_extension_and_mime_type()
     {
         Storage::fake('test');
+        Storage::disk('test')->put('foo.mp4a', '');
         Storage::disk('test')->put('.meta/foo.mp4a.yaml', YAML::dump(['mime_type' => 'audio/mp4']));
 
         $container = Facades\AssetContainer::make('test')->disk('test');
@@ -1415,6 +1416,7 @@ public function it_gets_dimensions_for_svgs()
     public function it_gets_no_ratio_when_height_is_zero()
     {
         Storage::fake('test');
+        Storage::disk('test')->put('image.jpg', '');
         Storage::disk('test')->put('.meta/image.jpg.yaml', YAML::dump(['width' => '30', 'height' => '0']));
 
         $container = Facades\AssetContainer::make('test')->disk('test');
@@ -2180,6 +2182,7 @@ public function it_syncs_original_state_with_no_data()
     /** @test */
     public function it_syncs_original_state_with_no_data_but_with_data_in_meta()
     {
+        Storage::disk('test')->put('path/to/test.txt', '');
         Storage::disk('test')->put('path/to/.meta/test.txt.yaml', "data:\n  foo: bar");
         $asset = (new Asset)->container($this->container)->path('path/to/test.txt');
 
@@ -2208,6 +2211,7 @@ public function it_syncs_original_state_with_no_data_but_with_data_in_meta()
     /** @test */
     public function it_syncs_original_state_with_data()
     {
+        Storage::disk('test')->put('path/to/test.txt', '');
         $yaml = <<<'YAML'
 data:
   alfa: bravo
@@ -2249,6 +2253,7 @@ public function it_syncs_original_state_with_data()
     /** @test */
     public function it_resolves_pending_original_meta_values_when_hydrating()
     {
+        Storage::disk('test')->put('path/to/test.txt', '');
         $yaml = <<<'YAML'
 data:
   alfa: bravo