Tests: Use FileSystem instead of DeprecatedFile

Author: https://github.com/cammo1123
Commit: 03008ec4e0
Pull-request: https://github.com/SerenityOS/serenity/pull/18026
Reviewed-by: https://github.com/ADKaster ✅
Reviewed-by: https://github.com/caoimhebyrne ✅
Reviewed-by: https://github.com/kleinesfilmroellchen ✅
Reviewed-by: https://github.com/linusg

Tests/LibC/TestIo.cpp

@@ -7,7 +7,7 @@
 
 #include <AK/Assertions.h>
 #include <AK/Types.h>
-#include <LibCore/DeprecatedFile.h>
+#include <LibFileSystem/FileSystem.h>
 #include <LibTest/TestCase.h>
 #include <fcntl.h>
 #include <stdio.h>
@@ -217,11 +217,11 @@ TEST_CASE(unlink_symlink)
         perror("symlink");
     }
 
-    auto target_or_error = Core::DeprecatedFile::read_link("/tmp/linky");
+    auto target_or_error = FileSystem::read_link("/tmp/linky"sv);
     EXPECT(!target_or_error.is_error());
 
     auto target = target_or_error.release_value();
-    EXPECT_EQ(target, "/proc/2/foo");
+    EXPECT_EQ(target.bytes_as_string_view(), "/proc/2/foo"sv);
 
     rc = unlink("/tmp/linky");
     EXPECT(rc >= 0);