Fix #413 parse entities positioning

[unintended]

Description

Please include a summary of the change and which issue is fixed. Please also include relevant motivation and context.

Fixes #413

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)

[JrooTJunior]

LGTM

Can you also make backport to dev-3.x branch with adding corresponding test that prove you changes?

And that is something strange. When i check entity length after adding MarkdownV2 i didn't see the need to use utf-16-le and then i remove it. So as i an see in your description i was wrong... Thanks

[unintended]

I updated the code: added tests, refactored encoding to methods, but didn't manage to put surrogates methods inside _unparse_entities. Maybe someone will try to make make it one day :)
Also tried to port to dev-3.x, but with no luck yet (couldn't port the tests properly becoase of different nature of api classes) and I don't have much time to do it, I'm sorry.

[JrooTJunior]

in dev-3.x you can add test-case to parameterized test of decorations:

aiogram/tests/test_utils/test_text_decorations.py

Lines 110 to 231 in 6f53f15

	@pytest.mark.parametrize(
	"decorator,text,entities,result",
	[
	[html_decoration, "test", None, "test"],
	[html_decoration, "test", [], "test"],
	[
	html_decoration,
	"test1 test2 test3 test4 test5 test6 test7",
	[
	MessageEntity(type="bold", offset=6, length=29),
	MessageEntity(type="underline", offset=12, length=5),
	MessageEntity(type="italic", offset=24, length=5),
	],
	"test1 <b>test2 <u>test3</u> test4 <i>test5</i> test6</b> test7",
	],
	[
	html_decoration,
	"test1 test2 test3 test4 test5",
	[
	MessageEntity(type="bold", offset=6, length=17),
	MessageEntity(type="underline", offset=12, length=5),
	],
	"test1 <b>test2 <u>test3</u> test4</b> test5",
	],
	[
	html_decoration,
	"test1 test2 test3 test4",
	[
	MessageEntity(type="bold", offset=6, length=11),
	MessageEntity(type="underline", offset=12, length=5),
	],
	"test1 <b>test2 <u>test3</u></b> test4",
	],
	[
	html_decoration,
	"test1 test2 test3",
	[MessageEntity(type="bold", offset=6, length=5)],
	"test1 <b>test2</b> test3",
	],
	[
	html_decoration,
	"test1 test2",
	[MessageEntity(type="bold", offset=0, length=5)],
	"<b>test1</b> test2",
	],
	[
	html_decoration,
	"strike bold",
	[
	MessageEntity(type="strikethrough", offset=0, length=6),
	MessageEntity(type="bold", offset=7, length=4),
	],
	"<s>strike</s> <b>bold</b>",
	],
	[
	html_decoration,
	"test",
	[
	MessageEntity(type="strikethrough", offset=0, length=5),
	MessageEntity(type="bold", offset=0, length=5),
	],
	"<s><b>test</b></s>",
	],
	[
	html_decoration,
	"strikeboldunder",
	[
	MessageEntity(type="strikethrough", offset=0, length=15),
	MessageEntity(type="bold", offset=6, length=9),
	MessageEntity(type="underline", offset=10, length=5),
	],
	"<s>strike<b>bold<u>under</u></b></s>",
	],
	[
	html_decoration,
	"@username",
	[
	MessageEntity(type="mention", offset=0, length=9),
	MessageEntity(type="bold", offset=0, length=9),
	],
	"<b>@username</b>",
	],
	[
	html_decoration,
	"/command",
	[
	MessageEntity(type="bot_command", offset=0, length=8),
	MessageEntity(type="bold", offset=0, length=8),
	],
	"<b>/command</b>",
	],
	[
	html_decoration,
	"+1-212-555-0123",
	[
	MessageEntity(type="phone_number", offset=0, length=15),
	MessageEntity(type="bold", offset=0, length=15),
	],
	"<b>+1-212-555-0123</b>",
	],
	[
	html_decoration,
	"test te👍🏿st test",
	[MessageEntity(type="bold", offset=5, length=6, url=None, user=None)],
	"test <b>te👍🏿st</b> test",
	],
	[
	html_decoration,
	"👋🏾 Hi!",
	[MessageEntity(type="bold", offset=0, length=8, url=None, user=None)],
	"<b>👋🏾 Hi!</b>",
	],
	],
	)
	def test_unparse(
	self,
	decorator: TextDecoration,
	text: str,
	entities: Optional[List[MessageEntity]],
	result: str,
	):
	assert decorator.unparse(text, entities) == result

and at the end of list add item:

[
    markdown_decoration,
    "🚀 i'm bold and italic and still bold",
    [
        MessageEntity(offset=3, length=34, type="bold"),
        MessageEntity(offset=12, length=10, type="italic"),
    ],
    "🚀 *i'm bold _and italic_\r and still bold*"
]

[JrooTJunior]

Thanks for contribution 😉