Fix dependency on manim for tests

This fixes a circular dependency between manim and manimpango.

Extracted from upstream:
https://github.com/ManimCommunity/ManimPango/commit/7e2b17aa14b10bd58af0598cc2de51a406682797

diff --git a/tests/_manim.py b/tests/_manim.py
index 3ea4676..b11d3e9 100644
--- a/tests/_manim.py
+++ b/tests/_manim.py
@@ -2,11 +2,12 @@
 """This file contains helpers for the tests copied and modified
 from Manim.
 """
-
+import copy
 import os
+import re
 from pathlib import Path

-from manimpango import Alignment, MarkupUtils
+from manimpango import Alignment, MarkupUtils, TextSetting, text2svg


 class MarkupText:
@@ -104,3 +105,115 @@ class MarkupText:

     def __repr__(self):
         return f"MarkupText({repr(self.original_text)})"
+
+
+class Text:
+    def __init__(
+        self,
+        text: str,
+        fill_opacity: float = 1.0,
+        stroke_width: int = 0,
+        size: int = 1,
+        line_spacing: int = -1,
+        font: str = "",
+        slant: str = "NORMAL",
+        weight: str = "NORMAL",
+        gradient: tuple = None,
+        tab_width: int = 4,
+        disable_ligatures: bool = False,
+        filename: str = "text.svg",
+        **kwargs,
+    ) -> None:
+        self.size = size
+        self.filename = filename
+        self.line_spacing = line_spacing
+        self.font = font
+        self.slant = slant
+        self.weight = weight
+        self.gradient = gradient
+        self.tab_width = tab_width
+        self.original_text = text
+        self.disable_ligatures = disable_ligatures
+        text_without_tabs = text
+        self.t2f = self.t2s = self.t2w = {}
+        if text.find("\t") != -1:
+            text_without_tabs = text.replace("\t", " " * self.tab_width)
+        self.text = text_without_tabs
+        if self.line_spacing == -1:
+            self.line_spacing = self.size + self.size * 0.3
+        else:
+            self.line_spacing = self.size + self.size * self.line_spacing
+        self.text2svg()
+
+    def text2settings(self):
+        """Internally used function. Converts the texts and styles
+        to a setting for parsing."""
+        settings = []
+        t2x = [self.t2f, self.t2s, self.t2w]
+        for i in range(len(t2x)):
+            fsw = [self.font, self.slant, self.weight]
+            if t2x[i]:
+                for word, x in list(t2x[i].items()):
+                    for start, end in self.find_indexes(word, self.text):
+                        fsw[i] = x
+                        settings.append(TextSetting(start, end, *fsw))
+        # Set all text settings (default font, slant, weight)
+        fsw = [self.font, self.slant, self.weight]
+        settings.sort(key=lambda setting: setting.start)
+        temp_settings = settings.copy()
+        start = 0
+        for setting in settings:
+            if setting.start != start:
+                temp_settings.append(TextSetting(start, setting.start, *fsw))
+            start = setting.end
+        if start != len(self.text):
+            temp_settings.append(TextSetting(start, len(self.text), *fsw))
+        settings = sorted(temp_settings, key=lambda setting: setting.start)
+
+        if re.search(r"\n", self.text):
+            line_num = 0
+            for start, end in self.find_indexes("\n", self.text):
+                for setting in settings:
+                    if setting.line_num == -1:
+                        setting.line_num = line_num
+                    if start < setting.end:
+                        line_num += 1
+                        new_setting = copy.copy(setting)
+                        setting.end = end
+                        new_setting.start = end
+                        new_setting.line_num = line_num
+                        settings.append(new_setting)
+                        settings.sort(key=lambda setting: setting.start)
+                        break
+        for setting in settings:
+            if setting.line_num == -1:
+                setting.line_num = 0
+        return settings
+
+    def text2svg(self):
+        """Internally used function.
+        Convert the text to SVG using Pango
+        """
+        size = self.size * 10
+        line_spacing = self.line_spacing * 10
+        dir_name = Path(self.filename).parent
+        disable_liga = self.disable_ligatures
+        if not os.path.exists(dir_name):
+            os.makedirs(dir_name)
+        file_name = self.filename
+        settings = self.text2settings()
+        width = 600
+        height = 400
+
+        return text2svg(
+            settings,
+            size,
+            line_spacing,
+            disable_liga,
+            file_name,
+            30,
+            30,
+            width,
+            height,
+            self.text,
+        )
diff --git a/tests/test_fonts.py b/tests/test_fonts.py
index 51e7eb4..da42895 100644
--- a/tests/test_fonts.py
+++ b/tests/test_fonts.py
@@ -3,13 +3,12 @@ import sys
 from pathlib import Path
 from shutil import copyfile

-import manim
 import pytest

 import manimpango

 from . import FONT_DIR
-from ._manim import MarkupText
+from ._manim import MarkupText, Text

 font_lists = {
     (FONT_DIR / "AdobeVFPrototype.ttf").absolute(): "Adobe Variable Font Prototype",
@@ -38,7 +37,7 @@ def test_register_font(font_name):
 @pytest.mark.parametrize("font_name", font_lists.values())
 def test_warning(capfd, font_name):
     print(font_name)
-    manim.Text("Testing", font=font_name)
+    Text("Testing", font=font_name)
     captured = capfd.readouterr()
     assert "Pango-WARNING **" not in captured.err, "Looks like pango raised a warning?"

--
2.32.0