test that `read_text` keeps symbols

tests/symbols.txt

+THIS IS A (SAMPLE) TEXT, CONTAINING (A LOT OF) PUNCTUATION!!

tests/test_read_text.py

@@ -4,3 +4,4 @@ def test_read_text():
     assert read_text("tests/sample.txt") == "this is a sample text file\n"
     assert read_text("tests/empty.txt") == ""
     assert read_text("tests/multiline.txt") == "i\nam\na\nmultiline\ntext\n"
+    assert read_text("tests/symbols.txt") == "this is a (sample) text, containing (a lot of) punctuation!!\n"