test/sandbox: parse full test case

This makes declaring multiple tests much cleaner.

Signed-off-by: Ophestra <cat@gensokyo.uk>

test/sandbox/fs_test.go

@@ -75,10 +75,4 @@ func TestCompare(t *testing.T) {
 			}
 		})
 	}
-
-	t.Run("assert", func(t *testing.T) {
-		oldFatal := sandbox.SwapFatal(t.Fatalf)
-		t.Cleanup(func() { sandbox.SwapFatal(oldFatal) })
-		sandbox.MustAssertFS(make(fstest.MapFS), sandbox.MustWantFile(t, &sandbox.FS{Mode: 0xDEADBEEF}))
-	})
 }