Assert a std::fs::read_to_string(path) value is less than or equal to an expression.
Pseudocode: std::fs::read_to_string(path) ≤ expr
let path = "alfa.txt"; let value = String::from("bravo\n"); assert_fs_read_to_string_le_expr!(&path, &value);
assert_fs_read_to_string_le_expr
assert_fs_read_to_string_le_expr_as_result
debug_assert_fs_read_to_string_le_expr