def test_substr_at_the_begin(self):
assert TextScanner("").substr(0) == ""
assert TextScanner("a").substr(1) == "a"
assert TextScanner("ab").substr(1) == "a", \
"do not return the char at the index itself"
assert TextScanner("ab").substr(2) == "ab"
assert TextScanner("ab").substr(3) == "ab"
def test_substr_from_consumed_string(self):
s = TextScanner("abcdef")
s.consume(2)
assert s.substr(2) == ""
assert s.substr(3) == "c"
assert s.substr(4) == "cd"
assert s.substr(10) == "cdef"
def test_substr_index_error(self):
with pytest.raises(IndexError):
TextScanner("").substr(-1)
s = TextScanner("abcd")
s.consume(2)
with pytest.raises(IndexError):
s.substr(1)
def test_can_not_consume_zero_chars(self):
s = TextScanner("w")
pytest.raises(ValueError, s.consume, 0)
def test_not_find_next(self):
assert TextScanner("").find(';') == -1
assert TextScanner("word").find(';') == -1
assert TextScanner("\\;").find(';', escape=True) == -1
def test_peeking_next_letter(self):
s = TextScanner("word")
assert s.peek() == "w"
def test_find_next_backslash(self):
assert TextScanner("\\").find('\\') == 0
assert TextScanner("a\\").find('\\', escape=False) == 1
assert TextScanner("a\\").find('\\', escape=True) == 1
assert TextScanner("a\\\\").find('\\', escape=True) == -1
assert TextScanner("a\\\\\\").find('\\', escape=True) == 3
def test_scan_empty_text(self):
s = TextScanner("")
assert s.is_empty is True
assert s.has_data is False
assert s.peek() == "" # empty string signals end of text
assert s.get() == ""
def test_find_next_char(self):
assert TextScanner(";").find(';') == 0
assert TextScanner("word;").find(';') == 4
assert TextScanner("word;;").find(';') == 4
def test_find_ignores_escaped_chars(self):
assert TextScanner("word\\;;").find(';', escape=True) == 6
assert TextScanner("word\\n;").find(';', escape=True) == 6
assert TextScanner("word\\;\\;;").find(';', escape=True) == 8
def test_can_not_consume_negative_chars(self):
s = TextScanner("w")
pytest.raises(ValueError, s.consume, -1)
def test_can_not_peek_in_reverse_direction(self):
s = TextScanner("w")
pytest.raises(ValueError, s.peek, -1)
def test_getting_all_letters_empties_scanner(self):
s = TextScanner("w")
s.get()
assert s.is_empty is True
assert s.has_data is False
def test_non_empty_string_is_not_empty(self):
s = TextScanner("word")
assert s.is_empty is False
assert s.has_data is True
def test_consume_two_letter(self):
s = TextScanner("word")
s.consume(2)
assert s.peek() == "r"
def test_consume_one_letter(self):
s = TextScanner("word")
s.consume()
assert s.peek() == "o"
def test_getting_next_letter_forwards_scan_position(self):
s = TextScanner("word")
assert s.get() == "w"
assert s.peek() == "o"
def test_peeking_beyond_word_boundaries_returns_empty_string(self):
s = TextScanner("word")
assert s.peek(4) == ""
def test_peeking_more_letters_ahead(self):
s = TextScanner("word")
assert s.peek(1) == "o"
assert s.peek(2) == "r"