diff --git a/tests/test_colour.py b/tests/test_colour.py
index bf0e59713..b79f153f0 100644
--- a/tests/test_colour.py
+++ b/tests/test_colour.py
@@ -44,6 +44,7 @@ import pytest
         ('rgb(20%, 24%, 56%)', 0x333D8F),
         ('rgb(20%, 23.9%, 56.1%)', 0x333D8F),
         ('rgb(51, 61, 143)', 0x333D8F),
+        ('0x#333D8F', 0x333D8F),
     ],
 )
 def test_from_str(value, expected):
@@ -53,6 +54,7 @@ def test_from_str(value, expected):
 @pytest.mark.parametrize(
     ('value'),
     [
+        None,
         'not valid',
         '0xYEAH',
         '#YEAH',
@@ -62,8 +64,72 @@ def test_from_str(value, expected):
         'rgb(30, -1, 60)',
         'invalid(a, b, c)',
         'rgb(',
+        '#1000000',
+        '#FFFFFFF',
+        "rgb(101%, 50%, 50%)",
+        "rgb(50%, -10%, 50%)",
+        "rgb(50%, 50%, 150%)",
+        "rgb(256, 100, 100)",
     ],
 )
 def test_from_str_failures(value):
     with pytest.raises(ValueError):
         discord.Colour.from_str(value)
+
+
+@pytest.mark.parametrize(
+    ('value', 'expected'),
+    [
+        (discord.Colour.default(), 0x000000),
+        (discord.Colour.teal(), 0x1ABC9C),
+        (discord.Colour.dark_teal(), 0x11806A),
+        (discord.Colour.brand_green(), 0x57F287),
+        (discord.Colour.green(), 0x2ECC71),
+        (discord.Colour.dark_green(), 0x1F8B4C),
+        (discord.Colour.blue(), 0x3498DB),
+        (discord.Colour.dark_blue(), 0x206694),
+        (discord.Colour.purple(), 0x9B59B6),
+        (discord.Colour.dark_purple(), 0x71368A),
+        (discord.Colour.magenta(), 0xE91E63),
+        (discord.Colour.dark_magenta(), 0xAD1457),
+        (discord.Colour.gold(), 0xF1C40F),
+        (discord.Colour.dark_gold(), 0xC27C0E),
+        (discord.Colour.orange(), 0xE67E22),
+        (discord.Colour.dark_orange(), 0xA84300),
+        (discord.Colour.brand_red(), 0xED4245),
+        (discord.Colour.red(), 0xE74C3C),
+        (discord.Colour.dark_red(), 0x992D22),
+        (discord.Colour.lighter_grey(), 0x95A5A6),
+        (discord.Colour.dark_grey(), 0x607D8B),
+        (discord.Colour.light_grey(), 0x979C9F),
+        (discord.Colour.darker_grey(), 0x546E7A),
+        (discord.Colour.og_blurple(), 0x7289DA),
+        (discord.Colour.blurple(), 0x5865F2),
+        (discord.Colour.greyple(), 0x99AAB5),
+        (discord.Colour.dark_theme(), 0x313338),
+        (discord.Colour.fuchsia(), 0xEB459E),
+        (discord.Colour.yellow(), 0xFEE75C),
+        (discord.Colour.dark_embed(), 0x2B2D31),
+        (discord.Colour.light_embed(), 0xEEEFF1),
+        (discord.Colour.pink(), 0xEB459F),
+    ],
+)
+def test_static_colours(value, expected):
+    assert value.value == expected
+
+
+
+
+@pytest.mark.parametrize(
+    ('value', 'property', 'expected'),
+    [
+        (discord.Colour(0x000000), 'r', 0),
+        (discord.Colour(0xFFFFFF), 'g', 255),
+        (discord.Colour(0xABCDEF), 'b', 239),
+        (discord.Colour(0x44243B), 'r', 68),
+        (discord.Colour(0x333D8F), 'g', 61),
+        (discord.Colour(0xDBFF00), 'b', 0),
+    ],
+)
+def test_colour_properties(value, property, expected):
+    assert getattr(value, property) == expected
diff --git a/tests/test_embed.py b/tests/test_embed.py
new file mode 100644
index 000000000..3efedd6a5
--- /dev/null
+++ b/tests/test_embed.py
@@ -0,0 +1,269 @@
+"""
+The MIT License (MIT)
+
+Copyright (c) 2015-present Rapptz
+
+Permission is hereby granted, free of charge, to any person obtaining a
+copy of this software and associated documentation files (the "Software"),
+to deal in the Software without restriction, including without limitation
+the rights to use, copy, modify, merge, publish, distribute, sublicense,
+and/or sell copies of the Software, and to permit persons to whom the
+Software is furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+DEALINGS IN THE SOFTWARE.
+"""
+
+from __future__ import annotations
+
+import datetime
+
+import discord
+import pytest
+
+
+@pytest.mark.parametrize(
+    ('title', 'description', 'colour', 'url'),
+    [
+        ('title', 'description', 0xABCDEF, 'https://example.com'),
+        ('title', 'description', 0xFF1294, None),
+        ('title', 'description', discord.Colour(0x333D8F), 'https://example.com'),
+        ('title', 'description', discord.Colour(0x44243B), None),
+    ],
+)
+def test_embed_initialization(title, description, colour, url):
+    embed = discord.Embed(title=title, description=description, colour=colour, url=url)
+    assert embed.title == title
+    assert embed.description == description
+    assert embed.colour == colour or embed.colour == discord.Colour(colour)
+    assert embed.url == url
+
+
+@pytest.mark.parametrize(
+    ('text', 'icon_url'),
+    [
+        ('Hello discord.py', 'https://example.com'),
+        ('text', None),
+        (None, 'https://example.com'),
+        (None, None),
+    ],
+)
+def test_embed_set_footer(text, icon_url):
+    embed = discord.Embed()
+    embed.set_footer(text=text, icon_url=icon_url)
+    assert embed.footer.text == text
+    assert embed.footer.icon_url == icon_url
+
+
+def test_embed_remove_footer():
+    embed = discord.Embed()
+    embed.set_footer(text='Hello discord.py', icon_url='https://example.com')
+    embed.remove_footer()
+    assert embed.footer.text is None
+    assert embed.footer.icon_url is None
+
+
+@pytest.mark.parametrize(
+    ('name', 'url', 'icon_url'),
+    [
+        ('Rapptz', 'http://example.com', 'http://example.com/icon.png'),
+        ('NCPlayz', None, 'http://example.com/icon.png'),
+        ('Jackenmen', 'http://example.com', None),
+    ],
+)
+def test_embed_set_author(name, url, icon_url):
+    embed = discord.Embed()
+    embed.set_author(name=name, url=url, icon_url=icon_url)
+    assert embed.author.name == name
+    assert embed.author.url == url
+    assert embed.author.icon_url == icon_url
+
+
+def test_embed_remove_author():
+    embed = discord.Embed()
+    embed.set_author(name='Rapptz', url='http://example.com', icon_url='http://example.com/icon.png')
+    embed.remove_author()
+    assert embed.author.name is None
+    assert embed.author.url is None
+    assert embed.author.icon_url is None
+
+
+@pytest.mark.parametrize(
+    ('thumbnail'),
+    [
+        ('http://example.com'),
+        (None),
+    ],
+)
+def test_embed_set_thumbnail(thumbnail):
+    embed = discord.Embed()
+    embed.set_thumbnail(url=thumbnail)
+    assert embed.thumbnail.url == thumbnail
+
+
+@pytest.mark.parametrize(
+    ('image'),
+    [
+        ('http://example.com'),
+        (None),
+    ],
+)
+def test_embed_set_image(image):
+    embed = discord.Embed()
+    embed.set_image(url=image)
+    assert embed.image.url == image
+
+
+@pytest.mark.parametrize(
+    ('name', 'value', 'inline'),
+    [
+        ('music', 'music value', True),
+        ('sport', 'sport value', False),
+    ],
+)
+def test_embed_add_field(name, value, inline):
+    embed = discord.Embed()
+    embed.add_field(name=name, value=value, inline=inline)
+    assert len(embed.fields) == 1
+    assert embed.fields[0].name == name
+    assert embed.fields[0].value == value
+    assert embed.fields[0].inline == inline
+
+
+def test_embed_insert_field():
+    embed = discord.Embed()
+    embed.add_field(name='name', value='value', inline=True)
+    embed.insert_field_at(0, name='name 2', value='value 2', inline=False)
+    assert embed.fields[0].name == 'name 2'
+    assert embed.fields[0].value == 'value 2'
+    assert embed.fields[0].inline is False
+
+
+def test_embed_set_field_at():
+    embed = discord.Embed()
+    embed.add_field(name='name', value='value', inline=True)
+    embed.set_field_at(0, name='name 2', value='value 2', inline=False)
+    assert embed.fields[0].name == 'name 2'
+    assert embed.fields[0].value == 'value 2'
+    assert embed.fields[0].inline is False
+
+
+def test_embed_set_field_at_failure():
+    embed = discord.Embed()
+    with pytest.raises(IndexError):
+        embed.set_field_at(0, name='name', value='value', inline=True)
+
+
+def test_embed_clear_fields():
+    embed = discord.Embed()
+    embed.add_field(name="field 1", value="value 1", inline=False)
+    embed.add_field(name="field 2", value="value 2", inline=False)
+    embed.add_field(name="field 3", value="value 3", inline=False)
+    embed.clear_fields()
+    assert len(embed.fields) == 0
+
+
+def test_embed_remove_field():
+    embed = discord.Embed()
+    embed.add_field(name='name', value='value', inline=True)
+    embed.remove_field(0)
+    assert len(embed.fields) == 0
+
+
+@pytest.mark.parametrize(
+    ('title', 'description', 'url'),
+    [
+        ('title 1', 'description 1', 'https://example.com'),
+        ('title 2', 'description 2', None),
+    ],
+)
+def test_embed_copy(title, description, url):
+    embed = discord.Embed(title=title, description=description, url=url)
+    embed_copy = embed.copy()
+
+    assert embed == embed_copy
+    assert embed.title == embed_copy.title
+    assert embed.description == embed_copy.description
+    assert embed.url == embed_copy.url
+
+
+@pytest.mark.parametrize(
+    ('title', 'description'),
+    [
+        ('title 1', 'description 1'),
+        ('title 2', 'description 2'),
+    ],
+)
+def test_embed_len(title, description):
+    embed = discord.Embed(title=title, description=description)
+    assert len(embed) == len(title) + len(description)
+
+
+@pytest.mark.parametrize(
+    ('title', 'description', 'fields', 'footer', 'author'),
+    [
+        (
+            'title 1',
+            'description 1',
+            [('field name 1', 'field value 1'), ('field name 2', 'field value 2')],
+            'footer 1',
+            'author 1',
+        ),
+        ('title 2', 'description 2', [('field name 3', 'field value 3')], 'footer 2', 'author 2'),
+    ],
+)
+def test_embed_len_with_options(title, description, fields, footer, author):
+    embed = discord.Embed(title=title, description=description)
+    for name, value in fields:
+        embed.add_field(name=name, value=value)
+    embed.set_footer(text=footer)
+    embed.set_author(name=author)
+    assert len(embed) == len(title) + len(description) + len("".join([name + value for name, value in fields])) + len(
+        footer
+    ) + len(author)
+
+
+def test_embed_to_dict():
+    timestamp = datetime.datetime.now(datetime.timezone.utc)
+    embed = discord.Embed(title="Test Title", description="Test Description", timestamp=timestamp)
+    data = embed.to_dict()
+    assert data['title'] == "Test Title"
+    assert data['description'] == "Test Description"
+    assert data['timestamp'] == timestamp.isoformat()
+
+
+def test_embed_from_dict():
+    data = {
+        'title': 'Test Title',
+        'description': 'Test Description',
+        'url': 'http://example.com',
+        'color': 0x00FF00,
+        'timestamp': '2024-07-03T12:34:56+00:00',
+    }
+    embed = discord.Embed.from_dict(data)
+    assert embed.title == 'Test Title'
+    assert embed.description == 'Test Description'
+    assert embed.url == 'http://example.com'
+    assert embed.colour is not None and embed.colour.value == 0x00FF00
+    assert embed.timestamp is not None and embed.timestamp.isoformat() == '2024-07-03T12:34:56+00:00'
+
+
+@pytest.mark.parametrize(
+    ('value'),
+    [
+        -0.5,
+        '#FFFFFF',
+    ],
+)
+def test_embed_colour_setter_failure(value):
+    embed = discord.Embed()
+    with pytest.raises(TypeError):
+        embed.colour = value
diff --git a/tests/test_files.py b/tests/test_files.py
index 6096c3a38..72ff3b7b3 100644
--- a/tests/test_files.py
+++ b/tests/test_files.py
@@ -27,6 +27,7 @@ from __future__ import annotations
 from io import BytesIO
 
 import discord
+import pytest
 
 
 FILE = BytesIO()
@@ -127,3 +128,58 @@ def test_file_not_spoiler_with_overriding_name_double_spoiler():
     f.filename = 'SPOILER_SPOILER_.gitignore'
     assert f.filename == 'SPOILER_.gitignore'
     assert f.spoiler == True
+
+
+def test_file_reset():
+    f = discord.File('.gitignore')
+
+    f.reset(seek=True)
+    assert f.fp.tell() == 0
+
+    f.reset(seek=False)
+    assert f.fp.tell() == 0
+
+
+def test_io_reset():
+    f = discord.File(FILE)
+
+    f.reset(seek=True)
+    assert f.fp.tell() == 0
+
+    f.reset(seek=False)
+    assert f.fp.tell() == 0
+
+
+def test_io_failure():
+    class NonSeekableReadable(BytesIO):
+        def seekable(self):
+            return False
+
+        def readable(self):
+            return False
+
+    f = NonSeekableReadable()
+
+    with pytest.raises(ValueError) as excinfo:
+        discord.File(f)
+
+    assert str(excinfo.value) == f"File buffer {f!r} must be seekable and readable"
+
+
+def test_io_to_dict():
+    buffer = BytesIO(b"test content")
+    file = discord.File(buffer, filename="test.txt", description="test description")
+
+    data = file.to_dict(0)
+    assert data["id"] == 0
+    assert data["filename"] == "test.txt"
+    assert data["description"] == "test description"
+
+
+def test_file_to_dict():
+    f = discord.File('.gitignore', description="test description")
+
+    data = f.to_dict(0)
+    assert data["id"] == 0
+    assert data["filename"] == ".gitignore"
+    assert data["description"] == "test description"
diff --git a/tests/test_ui_buttons.py b/tests/test_ui_buttons.py
new file mode 100644
index 000000000..55c0c7cd8
--- /dev/null
+++ b/tests/test_ui_buttons.py
@@ -0,0 +1,167 @@
+"""
+The MIT License (MIT)
+
+Copyright (c) 2015-present Rapptz
+
+Permission is hereby granted, free of charge, to any person obtaining a
+copy of this software and associated documentation files (the "Software"),
+to deal in the Software without restriction, including without limitation
+the rights to use, copy, modify, merge, publish, distribute, sublicense,
+and/or sell copies of the Software, and to permit persons to whom the
+Software is furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+DEALINGS IN THE SOFTWARE.
+"""
+
+from __future__ import annotations
+
+import discord
+import pytest
+
+
+def test_button_init():
+    button = discord.ui.Button(
+        label="Click me!",
+    )
+    assert button.label == "Click me!"
+    assert button.style == discord.ButtonStyle.secondary
+    assert button.disabled == False
+    assert button.url == None
+    assert button.emoji == None
+    assert button.sku_id == None
+
+
+def test_button_with_sku_id():
+    button = discord.ui.Button(
+        label="Click me!",
+        sku_id=1234567890,
+    )
+    assert button.label == "Click me!"
+    assert button.style == discord.ButtonStyle.premium
+    assert button.sku_id == 1234567890
+
+
+def test_button_with_url():
+    button = discord.ui.Button(
+        label="Click me!",
+        url="https://example.com",
+    )
+    assert button.label == "Click me!"
+    assert button.style == discord.ButtonStyle.link
+    assert button.url == "https://example.com"
+
+
+def test_mix_both_custom_id_and_url():
+    with pytest.raises(TypeError):
+        discord.ui.Button(
+            label="Click me!",
+            url="https://example.com",
+            custom_id="test",
+        )
+
+
+def test_mix_both_custom_id_and_sku_id():
+    with pytest.raises(TypeError):
+        discord.ui.Button(
+            label="Click me!",
+            sku_id=1234567890,
+            custom_id="test",
+        )
+
+
+def test_mix_both_url_and_sku_id():
+    with pytest.raises(TypeError):
+        discord.ui.Button(
+            label="Click me!",
+            url="https://example.com",
+            sku_id=1234567890,
+        )
+
+
+def test_invalid_url():
+    button = discord.ui.Button(
+        label="Click me!",
+    )
+    with pytest.raises(TypeError):
+        button.url = 1234567890  # type: ignore
+
+
+def test_invalid_custom_id():
+    with pytest.raises(TypeError):
+        discord.ui.Button(
+            label="Click me!",
+            custom_id=1234567890,  # type: ignore
+        )
+
+    button = discord.ui.Button(
+        label="Click me!",
+    )
+    with pytest.raises(TypeError):
+        button.custom_id = 1234567890  # type: ignore
+
+
+def test_button_with_partial_emoji():
+    button = discord.ui.Button(
+        label="Click me!",
+        emoji="👍",
+    )
+    assert button.label == "Click me!"
+    assert button.emoji is not None and button.emoji.name == "👍"
+
+
+def test_button_with_str_emoji():
+    emoji = discord.PartialEmoji(name="👍")
+    button = discord.ui.Button(
+        label="Click me!",
+        emoji=emoji,
+    )
+    assert button.label == "Click me!"
+    assert button.emoji == emoji
+
+
+def test_button_with_invalid_emoji():
+    with pytest.raises(TypeError):
+        discord.ui.Button(
+            label="Click me!",
+            emoji=-0.53,  # type: ignore
+        )
+
+    button = discord.ui.Button(
+        label="Click me!",
+    )
+    with pytest.raises(TypeError):
+        button.emoji = -0.53  # type: ignore
+
+
+def test_button_setter():
+    button = discord.ui.Button()
+
+    button.label = "Click me!"
+    assert button.label == "Click me!"
+
+    button.style = discord.ButtonStyle.primary
+    assert button.style == discord.ButtonStyle.primary
+
+    button.disabled = True
+    assert button.disabled == True
+
+    button.url = "https://example.com"
+    assert button.url == "https://example.com"
+
+    button.emoji = "👍"
+    assert button.emoji is not None and button.emoji.name == "👍"  # type: ignore
+
+    button.custom_id = "test"
+    assert button.custom_id == "test"
+
+    button.sku_id = 1234567890
+    assert button.sku_id == 1234567890
diff --git a/tests/test_ui_modals.py b/tests/test_ui_modals.py
new file mode 100644
index 000000000..dd1ac7169
--- /dev/null
+++ b/tests/test_ui_modals.py
@@ -0,0 +1,102 @@
+"""
+The MIT License (MIT)
+
+Copyright (c) 2015-present Rapptz
+
+Permission is hereby granted, free of charge, to any person obtaining a
+copy of this software and associated documentation files (the "Software"),
+to deal in the Software without restriction, including without limitation
+the rights to use, copy, modify, merge, publish, distribute, sublicense,
+and/or sell copies of the Software, and to permit persons to whom the
+Software is furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+DEALINGS IN THE SOFTWARE.
+"""
+
+from __future__ import annotations
+
+import discord
+import pytest
+
+
+@pytest.mark.asyncio
+async def test_modal_init():
+    modal = discord.ui.Modal(
+        title="Temp Title",
+    )
+    assert modal.title == "Temp Title"
+    assert modal.timeout == None
+
+
+@pytest.mark.asyncio
+async def test_no_title():
+    with pytest.raises(ValueError) as excinfo:
+        discord.ui.Modal()
+
+    assert str(excinfo.value) == "Modal must have a title"
+
+
+@pytest.mark.asyncio
+async def test_to_dict():
+    modal = discord.ui.Modal(
+        title="Temp Title",
+    )
+    data = modal.to_dict()
+    assert data["custom_id"] is not None
+    assert data["title"] == "Temp Title"
+    assert data["components"] == []
+
+
+@pytest.mark.asyncio
+async def test_add_item():
+    modal = discord.ui.Modal(
+        title="Temp Title",
+    )
+    item = discord.ui.TextInput(label="Test")
+    modal.add_item(item)
+
+    assert modal.children == [item]
+
+
+@pytest.mark.asyncio
+async def test_add_item_invalid():
+    modal = discord.ui.Modal(
+        title="Temp Title",
+    )
+    with pytest.raises(TypeError):
+        modal.add_item("Not an item")  # type: ignore
+
+
+@pytest.mark.asyncio
+async def test_maximum_items():
+    modal = discord.ui.Modal(
+        title="Temp Title",
+    )
+    max_item_limit = 5
+
+    for i in range(max_item_limit):
+        modal.add_item(discord.ui.TextInput(label=f"Test {i}"))
+
+    with pytest.raises(ValueError):
+        modal.add_item(discord.ui.TextInput(label="Test"))
+
+
+@pytest.mark.asyncio
+async def test_modal_setters():
+    modal = discord.ui.Modal(
+        title="Temp Title",
+    )
+    modal.title = "New Title"
+    assert modal.title == "New Title"
+
+    modal.timeout = 120
+    assert modal.timeout == 120