diff --git a/install.py b/install.py
index 1c2f84c..5d3b6c0 100644
--- a/install.py
+++ b/install.py
@@ -1,6 +1,6 @@
 # This file installs Marble shell theme for GNOME DE
 # Copyright (C) 2023-2025  Vladyslav Hroshev
-
+import os
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
 # the Free Software Foundation, either version 3 of the License, or
@@ -22,6 +22,7 @@ from scripts.install.colors_definer import ColorsDefiner
 from scripts.install.global_theme_installer import GlobalThemeInstaller
 from scripts.install.local_theme_installer import LocalThemeInstaller
 from scripts.utils.gnome import apply_gnome_theme
+from scripts.utils.logger.console import Console
 
 
 def main():
@@ -31,6 +32,12 @@ def main():
     installer_class = GlobalThemeInstaller if args.gdm else LocalThemeInstaller
     installer = installer_class(args, colors_definer)
 
+    if args.gdm:
+        if os.getuid() != 0:
+            Console().Line().error(
+                "Global installation requires root privileges. Please run the script as root.")
+            return
+
     if args.remove or args.reinstall:
         installer.remove()
 
diff --git a/scripts/install/global_theme_installer.py b/scripts/install/global_theme_installer.py
index 0550081..77e3470 100644
--- a/scripts/install/global_theme_installer.py
+++ b/scripts/install/global_theme_installer.py
@@ -1,6 +1,6 @@
 from scripts.install.theme_installer import ThemeInstaller
 from scripts.utils.global_theme.gdm import GDMTheme
-from scripts.utils.global_theme.gdm_builder import GdmBuilder
+from scripts.utils.global_theme.gdm_builder import GDMThemeBuilder
 from scripts.utils.logger.console import Console, Color, Format
 
 
@@ -13,7 +13,7 @@ class GlobalThemeInstaller(ThemeInstaller):
             print("GDM theme removed successfully.")
 
     def _define_theme(self):
-        gdm_builder = GdmBuilder(self.colors)
+        gdm_builder = GDMThemeBuilder(self.colors)
         gdm_builder.with_mode(self.args.mode)
         gdm_builder.with_filled(self.args.filled)
         self.theme = gdm_builder.build()
diff --git a/scripts/utils/files_labeler.py b/scripts/utils/files_labeler.py
index 6243f7a..1107f45 100644
--- a/scripts/utils/files_labeler.py
+++ b/scripts/utils/files_labeler.py
@@ -1,15 +1,28 @@
 import os
+from abc import ABC, abstractmethod
 from typing import Tuple, TypeAlias
 
 LabeledFileGroup: TypeAlias = Tuple[str, str]
 
+
+class FilesLabelerFactory(ABC):
+    @abstractmethod
+    def create(self, temp_folder: str, *files_to_update_references: str) -> 'FilesLabeler':
+        pass
+
+
+class FilesLabelerFactoryImpl(FilesLabelerFactory):
+    def create(self, temp_folder: str, *files_to_update_references: str) -> 'FilesLabeler':
+        return FilesLabeler(temp_folder, *files_to_update_references)
+
+
 class FilesLabeler:
-    def __init__(self, directory: str, *args: str):
+    def __init__(self, directory: str, *files_to_update_references: str):
         """
         Initialize the working directory and files to change
         """
         self.directory = directory
-        self.files = args
+        self.files = files_to_update_references
 
     def append_label(self, label: str):
         """
diff --git a/scripts/utils/global_theme/gdm_builder.py b/scripts/utils/global_theme/gdm_builder.py
index edf87f1..31ea366 100644
--- a/scripts/utils/global_theme/gdm_builder.py
+++ b/scripts/utils/global_theme/gdm_builder.py
@@ -6,6 +6,7 @@ from scripts.install.colors_definer import ColorsDefiner
 from scripts.types.installation_color import InstallationMode
 from scripts.utils.alternatives_updater import AlternativesUpdater, PathString
 from scripts.utils.command_runner.subprocess_command_runner import SubprocessCommandRunner
+from scripts.utils.files_labeler import FilesLabelerFactoryImpl
 from scripts.utils.global_theme.gdm import GDMTheme
 from scripts.utils.global_theme.gdm_installer import GDMThemeInstaller
 from scripts.utils.global_theme.gdm_preparer import GDMThemePreparer
@@ -17,7 +18,7 @@ from scripts.utils.logger.logger import LoggerFactory
 from scripts.utils.theme.gnome_shell_theme_builder import GnomeShellThemeBuilder
 
 
-class GdmBuilder:
+class GDMThemeBuilder:
     """
     Builder class for creating GDMTheme instances with configurable components.
 
@@ -26,7 +27,7 @@ class GdmBuilder:
     automatically resolved during build() if not provided.
 
     Example usage:
-        builder = GdmBuilder(colors_provider)
+        builder = GMDThemeBuilder(colors_provider)
         theme = builder.with_mode("dark").with_filled(True).build()
     """
     def __init__(self, colors_provider: ColorsDefiner):
@@ -46,42 +47,42 @@ class GdmBuilder:
         self._installer: Optional[GDMThemeInstaller] = None
         self._remover: Optional[GDMThemeRemover] = None
 
-    def with_mode(self, mode: InstallationMode | None) -> 'GdmBuilder':
+    def with_mode(self, mode: InstallationMode | None) -> 'GDMThemeBuilder':
         """Set the mode for the theme."""
         self._mode = mode
         return self
 
-    def with_filled(self, is_filled=True) -> 'GdmBuilder':
+    def with_filled(self, is_filled=True) -> 'GDMThemeBuilder':
         """Set the filled state for the theme."""
         self._is_filled = is_filled
         return self
 
-    def with_logger_factory(self, logger_factory: LoggerFactory) -> 'GdmBuilder':
+    def with_logger_factory(self, logger_factory: LoggerFactory) -> 'GDMThemeBuilder':
         """Inject a logger factory for logging purposes."""
         self._logger_factory = logger_factory
         return self
 
-    def with_gresource(self, gresource: Gresource) -> 'GdmBuilder':
+    def with_gresource(self, gresource: Gresource) -> 'GDMThemeBuilder':
         """Inject a gresource instance for managing gresource files."""
         self._gresource = gresource
         return self
 
-    def with_ubuntu_gdm_alternatives_updater(self, alternatives_updater: UbuntuGDMAlternativesUpdater) -> 'GdmBuilder':
+    def with_ubuntu_gdm_alternatives_updater(self, alternatives_updater: UbuntuGDMAlternativesUpdater) -> 'GDMThemeBuilder':
         """Inject an alternatives updater for managing GDM alternatives."""
         self._ubuntu_gdm_alternatives_updater = alternatives_updater
         return self
 
-    def with_preparer(self, preparer: GDMThemePreparer) -> 'GdmBuilder':
+    def with_preparer(self, preparer: GDMThemePreparer) -> 'GDMThemeBuilder':
         """Inject a preparer for preparing the theme."""
         self._preparer = preparer
         return self
 
-    def with_installer(self, installer: GDMThemeInstaller) -> 'GdmBuilder':
+    def with_installer(self, installer: GDMThemeInstaller) -> 'GDMThemeBuilder':
         """Inject an installer for installing the theme."""
         self._installer = installer
         return self
 
-    def with_remover(self, remover: GDMThemeRemover) -> 'GdmBuilder':
+    def with_remover(self, remover: GDMThemeRemover) -> 'GDMThemeBuilder':
         """Inject a remover for removing the theme."""
         self._remover = remover
         return self
@@ -141,13 +142,15 @@ class GdmBuilder:
         """Create a GDMThemePreparer if not explicitly provided."""
         if self._preparer: return
         theme_builder = GnomeShellThemeBuilder(self.colors_provider)
+        files_labeler_factory = FilesLabelerFactoryImpl()
         self._preparer = GDMThemePreparer(
             temp_folder=self._temp_folder,
             default_mode=self._mode,
             is_filled=self._is_filled,
             gresource=self._gresource,
             theme_builder=theme_builder,
-            logger_factory=self._logger_factory
+            logger_factory=self._logger_factory,
+            files_labeler_factory=files_labeler_factory,
         )
 
     def _resolve_installer(self):
diff --git a/scripts/utils/global_theme/gdm_preparer.py b/scripts/utils/global_theme/gdm_preparer.py
index a585c8f..3af77e6 100644
--- a/scripts/utils/global_theme/gdm_preparer.py
+++ b/scripts/utils/global_theme/gdm_preparer.py
@@ -1,5 +1,6 @@
 import os
 
+from scripts.utils.files_labeler import FilesLabelerFactory
 from scripts.utils.global_theme.gdm_theme_prepare import GDMThemePrepare
 from scripts.utils.gresource.gresource import Gresource
 from scripts.utils.logger.logger import LoggerFactory
@@ -19,13 +20,16 @@ class GDMThemePreparer:
     def __init__(self, temp_folder: str, default_mode: str | None, is_filled: bool,
                  gresource: Gresource,
                  theme_builder: GnomeShellThemeBuilder,
-                 logger_factory: LoggerFactory):
+                 logger_factory: LoggerFactory,
+                 files_labeler_factory: FilesLabelerFactory):
         """
         :param temp_folder: Temporary folder for extracted theme files
         :param default_mode: Default theme mode to use if not specified in CSS filename
-        :param is_filled: Whether to generate filled (True) or outlined (False) styles
+        :param is_filled: Whether to generate filled (True) or dimmed (False) styles
         :param gresource: Gresource instance for managing gresource files
         :param theme_builder: Theme builder instance for creating themes
+        :param logger_factory: Logger factory for logging messages
+        :param files_labeler_factory: Factory for creating FilesLabeler instances
         """
         self.temp_folder = temp_folder
         self.gresource_temp_folder = gresource.temp_folder
@@ -36,6 +40,7 @@ class GDMThemePreparer:
         self.gresource = gresource
         self.theme_builder = theme_builder
         self.logger_factory = logger_factory
+        self.files_labeler_factory = files_labeler_factory
 
     def use_backup_as_source(self):
         """Use backup gresource file for extraction"""
@@ -72,11 +77,12 @@ class GDMThemePreparer:
         theme.prepare()
 
         theme_file = os.path.join(self.gresource_temp_folder, file_name)
-        return GDMThemePrepare(theme=theme, theme_file=theme_file, label=mode)
+        files_labeler = self.files_labeler_factory.create(
+            theme.temp_folder, theme.main_styles)
+        return GDMThemePrepare(
+            theme=theme, theme_file=theme_file, label=mode, files_labeler=files_labeler)
 
     def _setup_theme_builder(self, file_name: str, mode: str):
-        self.theme_builder.with_temp_folder(self.temp_folder)
-
         theme_name = file_name.replace(".css", "")
 
         (self.theme_builder
diff --git a/scripts/utils/global_theme/gdm_theme_prepare.py b/scripts/utils/global_theme/gdm_theme_prepare.py
index b261e33..66db0d7 100644
--- a/scripts/utils/global_theme/gdm_theme_prepare.py
+++ b/scripts/utils/global_theme/gdm_theme_prepare.py
@@ -12,15 +12,18 @@ class GDMThemePrepare:
     - CSS property and keyword removal for customization
     - Theme installation with color adjustments
     """
-    def __init__(self, theme: Theme, theme_file: str, label: str = None):
+    def __init__(self, theme: Theme, theme_file: str, label: str | None,
+                 files_labeler: FilesLabeler):
         """
         :param theme: The theme object to prepare
         :param theme_file: Path to the original decompiled CSS file
         :param label: Optional label for the theme (e.g. "dark", "light")
+        :param files_labeler: FilesLabeler instance for labeling files
         """
         self.theme = theme
         self.theme_file = theme_file
         self.label = label
+        self.files_labeler = files_labeler
 
     def label_theme(self):
         """
@@ -31,8 +34,7 @@ class GDMThemePrepare:
         if self.label is None:
             raise ValueError("Label is not set for the theme.")
 
-        files_labeler = FilesLabeler(self.theme.temp_folder, self.theme.main_styles)
-        files_labeler.append_label(self.label)
+        self.files_labeler.append_label(self.label)
 
     def remove_keywords(self, *args: str):
         """Remove specific keywords from the theme file"""
@@ -52,7 +54,7 @@ class GDMThemePrepare:
         :param trigger: String marker used to identify installed themes
         """
         with open(self.theme_file, 'r') as gnome_theme:
-            gnome_styles = gnome_theme.read() + trigger
+            gnome_styles = gnome_theme.read() + '\n' + trigger + '\n'
             self.theme.add_to_start(gnome_styles)
 
     def install(self, hue: int, color: str, sat: int | None, destination: str):
diff --git a/scripts/utils/global_theme/ubuntu_alternatives_updater.py b/scripts/utils/global_theme/ubuntu_alternatives_updater.py
index c067d9a..351cb5d 100644
--- a/scripts/utils/global_theme/ubuntu_alternatives_updater.py
+++ b/scripts/utils/global_theme/ubuntu_alternatives_updater.py
@@ -17,7 +17,7 @@ class UbuntuGDMAlternativesUpdater:
         """
         :param alternatives_updater: Handler for update-alternatives operations
         """
-        self.ubuntu_gresource_link = config.ubuntu_gresource_link
+        self.ubuntu_gresource_link_name = config.ubuntu_gresource_link
         self.destination_dir = config.global_gnome_shell_theme
         self.destination_file = config.gnome_shell_gresource
 
@@ -26,7 +26,7 @@ class UbuntuGDMAlternativesUpdater:
         self._update_gresource_paths()
 
     def _update_gresource_paths(self):
-        self.ubuntu_gresource_path = os.path.join(self.destination_dir, self.ubuntu_gresource_link)
+        self.ubuntu_gresource_path = os.path.join(self.destination_dir, self.ubuntu_gresource_link_name)
         self.gnome_gresource_path = os.path.join(self.destination_dir, self.destination_file)
 
     def with_custom_destination(self, destination_dir: str, destination_file: str):
@@ -47,7 +47,7 @@ class UbuntuGDMAlternativesUpdater:
         """
         self.alternatives_updater.install_and_set(
             link=self.ubuntu_gresource_path,
-            name=self.ubuntu_gresource_link,
+            name=self.ubuntu_gresource_link_name,
             path=self.gnome_gresource_path,
             priority=priority
         )
@@ -60,6 +60,6 @@ class UbuntuGDMAlternativesUpdater:
         the system to fall back to the default GDM theme.
         """
         self.alternatives_updater.remove(
-            name=self.ubuntu_gresource_link,
+            name=self.ubuntu_gresource_link_name,
             path=self.gnome_gresource_path
         )
diff --git a/scripts/utils/remove_properties.py b/scripts/utils/remove_properties.py
index eed79ce..f20ef5e 100644
--- a/scripts/utils/remove_properties.py
+++ b/scripts/utils/remove_properties.py
@@ -10,10 +10,10 @@ def remove_properties(file, *args):
     with open(file, "r") as read_file:
         content = read_file.read()
 
-        for line in content.splitlines():
+        for i, line in enumerate(content.splitlines()):
             if not any(prop in line for prop in args):
                 new_content += line + "\n"
-            elif "}" in line:
+            elif "}" in line and not "{" in line:
                 new_content += "}\n"
 
     with open(file, "w") as write_file:
diff --git a/tests/utils/global_theme/__init__.py b/tests/utils/global_theme/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/tests/utils/global_theme/test_gdm.py b/tests/utils/global_theme/test_gdm.py
new file mode 100644
index 0000000..4906086
--- /dev/null
+++ b/tests/utils/global_theme/test_gdm.py
@@ -0,0 +1,81 @@
+from unittest import TestCase
+from unittest.mock import Mock
+
+from scripts.utils.global_theme.gdm import GDMTheme
+from scripts.utils.global_theme.gdm_installer import GDMThemeInstaller
+from scripts.utils.global_theme.gdm_preparer import GDMThemePreparer
+from scripts.utils.global_theme.gdm_remover import GDMThemeRemover
+
+
+class GDMTestCase(TestCase):
+    def setUp(self):
+        self.preparer = Mock(spec=GDMThemePreparer)
+        self.installer = Mock(spec=GDMThemeInstaller)
+        self.remover = Mock(spec=GDMThemeRemover)
+
+        self.gdm = GDMTheme(self.preparer, self.installer, self.remover)
+
+    def test_prepare_uses_backup_if_installed(self):
+        self.installer.is_installed.return_value = True
+
+        self.gdm.prepare()
+
+        self.preparer.use_backup_as_source.assert_called_once()
+
+    def test_prepare_does_not_use_backup_if_not_installed(self):
+        self.installer.is_installed.return_value = False
+
+        self.gdm.prepare()
+
+        self.preparer.use_backup_as_source.assert_not_called()
+
+    def test_prepare_calls_preparer_prepare_and_sets_themes(self):
+        mock_theme = Mock()
+        self.preparer.prepare.return_value = [mock_theme]
+
+        self.gdm.prepare()
+
+        self.preparer.prepare.assert_called_once()
+        self.assertEqual(self.gdm.themes, [mock_theme])
+
+    def test_install_correctly_passes_arguments_to_installer_compile(self):
+        hue = 100
+        name = "test_theme"
+        sat = 0.5
+
+        self.gdm.install(hue, name, sat)
+
+        self.installer.compile.assert_called_once_with(self.gdm.themes, hue, name, sat)
+
+    def test_install_calls_installer_backup_if_not_installed(self):
+        self.installer.is_installed.return_value = False
+
+        self.gdm.install(100, "test_theme")
+
+        self.installer.backup.assert_called_once()
+
+    def test_install_does_not_call_installer_backup_if_installed(self):
+        self.installer.is_installed.return_value = True
+
+        self.gdm.install(100, "test_theme")
+
+        self.installer.backup.assert_not_called()
+
+    def test_install_calls_installer_install(self):
+        self.gdm.install(100, "test_theme")
+
+        self.installer.install.assert_called_once()
+
+    def test_remove_calls_installer_remove_if_installed(self):
+        self.installer.is_installed.return_value = True
+
+        self.gdm.remove()
+
+        self.remover.remove.assert_called_once()
+
+    def test_remove_calls_installer_warn_if_not_installed(self):
+        self.installer.is_installed.return_value = False
+
+        self.gdm.remove()
+
+        self.remover.remove.assert_not_called()
\ No newline at end of file
diff --git a/tests/utils/global_theme/test_gdm_builder.py b/tests/utils/global_theme/test_gdm_builder.py
new file mode 100644
index 0000000..e01012a
--- /dev/null
+++ b/tests/utils/global_theme/test_gdm_builder.py
@@ -0,0 +1,155 @@
+from unittest import TestCase
+from unittest.mock import Mock
+
+from scripts.types.installation_color import InstallationMode
+from scripts.utils.global_theme.gdm_builder import GDMThemeBuilder
+
+
+class GDMBuilderTestCase(TestCase):
+    def setUp(self):
+        self.colors_provider = Mock()
+        self.builder = GDMThemeBuilder(colors_provider=self.colors_provider)
+
+    def test_with_mode_sets_correct_mode(self):
+        self.builder._mode = None
+        mode: InstallationMode = "dark"
+
+        builder = self.builder.with_mode(mode)
+
+        self.assertEqual(builder._mode, mode)
+
+    def test_with_filled_sets_correct_filled_state(self):
+        self.builder._is_filled = False
+        is_filled = True
+
+        builder = self.builder.with_filled(is_filled)
+
+        self.assertEqual(builder._is_filled, is_filled)
+
+    def test_with_logger_factory_sets_specified_logger_factory(self):
+        logger_factory = Mock()
+        builder = self.builder.with_logger_factory(logger_factory)
+        self.assertEqual(builder._logger_factory, logger_factory)
+
+    def test_with_gresource_sets_specified_gresource(self):
+        gresource = Mock()
+        builder = self.builder.with_gresource(gresource)
+        self.assertEqual(builder._gresource, gresource)
+
+    def test_with_ubuntu_gdm_alternatives_updater_sets_specified_updater(self):
+        alternatives_updater = Mock()
+        builder = self.builder.with_ubuntu_gdm_alternatives_updater(alternatives_updater)
+        self.assertEqual(builder._ubuntu_gdm_alternatives_updater, alternatives_updater)
+
+    def test_with_preparer_sets_specified_preparer(self):
+        preparer = Mock()
+        builder = self.builder.with_preparer(preparer)
+        self.assertEqual(builder._preparer, preparer)
+
+    def test_with_installer_sets_specified_installer(self):
+        installer = Mock()
+        builder = self.builder.with_installer(installer)
+        self.assertEqual(builder._installer, installer)
+
+    def test_with_remover_sets_specified_remover(self):
+        remover = Mock()
+        builder = self.builder.with_remover(remover)
+        self.assertEqual(builder._remover, remover)
+
+    def test_resolve_logger_factory_initializes_logger_factory(self):
+        self.builder._logger_factory = None
+
+        self.builder._resolve_logger_factory()
+
+        self.assertIsNotNone(self.builder._logger_factory)
+
+    def test_resolve_gresource_initializes_gresource(self):
+        self.builder._logger_factory = Mock()
+        self.builder._gresource = None
+
+        self.builder._resolve_gresource()
+
+        self.assertIsNotNone(self.builder._gresource)
+
+    def test_builder_supports_chaining(self):
+        theme = self.builder.with_mode("dark").with_filled(True).build()
+
+        self.assertIsNotNone(theme)
+
+    def test_resolve_ubuntu_gdm_alternatives_updater_initializes_gresource(self):
+        self.builder._logger_factory = Mock()
+        self.builder._gresource = Mock()
+        self.builder._ubuntu_gdm_alternatives_updater = None
+        self.builder._resolve_ubuntu_gdm_alternatives_updater()
+        self.assertIsNotNone(self.builder._ubuntu_gdm_alternatives_updater)
+
+    def test_resolve_preparer_initializes_preparer(self):
+        self.builder._logger_factory = Mock()
+        self.builder._gresource = Mock()
+        self.builder._ubuntu_gdm_alternatives_updater = Mock()
+        self.builder._preparer = None
+
+        self.builder._resolve_preparer()
+
+        self.assertIsNotNone(self.builder._preparer)
+
+    def test_resolve_installer_initializes_installer(self):
+        self.builder._gresource = Mock()
+        self.builder._ubuntu_gdm_alternatives_updater = Mock()
+        self.builder._installer = None
+
+        self.builder._resolve_installer()
+
+        self.assertIsNotNone(self.builder._installer)
+
+    def test_resolve_remover_initializes_remover(self):
+        self.builder._gresource = Mock()
+        self.builder._ubuntu_gdm_alternatives_updater = Mock()
+        self.builder._remover = None
+
+        self.builder._resolve_remover()
+
+        self.assertIsNotNone(self.builder._remover)
+
+    def test_build_resolves_dependencies(self):
+        self.builder._resolve_logger_factory = Mock()
+        self.builder._resolve_gresource = Mock()
+        self.builder._resolve_ubuntu_gdm_alternatives_updater = Mock()
+        self.builder._resolve_preparer = Mock()
+        self.builder._resolve_installer = Mock()
+        self.builder._resolve_remover = Mock()
+
+        self.builder.build()
+
+        self.builder._resolve_logger_factory.assert_called_once()
+        self.builder._resolve_gresource.assert_called_once()
+        self.builder._resolve_ubuntu_gdm_alternatives_updater.assert_called_once()
+        self.builder._resolve_preparer.assert_called_once()
+        self.builder._resolve_installer.assert_called_once()
+        self.builder._resolve_remover.assert_called_once()
+
+    def test_build_correctly_builds_gdm_theme(self):
+        self.builder._preparer = Mock()
+        self.builder._installer = Mock()
+        self.builder._remover = Mock()
+
+        result = self.builder.build()
+
+        self.assertEqual(result.preparer, self.builder._preparer)
+        self.assertEqual(result.installer, self.builder._installer)
+        self.assertEqual(result.remover, self.builder._remover)
+
+    def test_build_with_explicit_dependencies_works_correctly(self):
+        preparer = Mock()
+        installer = Mock()
+        remover = Mock()
+        builder = (self.builder
+                   .with_preparer(preparer)
+                   .with_installer(installer)
+                   .with_remover(remover))
+
+        result = builder.build()
+
+        self.assertEqual(result.preparer, preparer)
+        self.assertEqual(result.installer, installer)
+        self.assertEqual(result.remover, remover)
\ No newline at end of file
diff --git a/tests/utils/global_theme/test_gdm_installer.py b/tests/utils/global_theme/test_gdm_installer.py
new file mode 100644
index 0000000..79bc558
--- /dev/null
+++ b/tests/utils/global_theme/test_gdm_installer.py
@@ -0,0 +1,87 @@
+import os.path
+from unittest import TestCase
+from unittest.mock import MagicMock
+
+from scripts import config
+from scripts.utils.global_theme.gdm_installer import GDMThemeInstaller
+
+
+class GDMInstallerTestCase(TestCase):
+    def setUp(self):
+        self.temp_folder = os.path.join(config.temp_tests_folder, "gdm_installer")
+        self.gresource = MagicMock()
+        self.gresource.temp_folder = self.temp_folder
+
+        self.alternatives_updater = MagicMock()
+
+        self.gdm_installer = GDMThemeInstaller(
+            gresource=self.gresource,
+            alternatives_updater=self.alternatives_updater
+        )
+
+    def test_is_installed_return_the_same_value_as_gresource(self):
+        self.gresource.has_trigger.return_value = True
+
+        result = self.gdm_installer.is_installed()
+
+        self.assertTrue(result)
+        self.gresource.has_trigger.assert_called_once()
+
+    def test_compile_does_not_call_label_theme_if_label_is_none(self):
+        theme_prepare = MagicMock()
+        theme_prepare.label = None
+        theme_prepare.label_theme = MagicMock()
+
+        self.gdm_installer.compile(themes=[theme_prepare], hue=0, color="red", sat=None)
+
+        theme_prepare.label_theme.assert_not_called()
+
+    def test_compile_calls_label_theme_if_label_is_set(self):
+        theme_prepare = MagicMock()
+        theme_prepare.label = "dark"
+        theme_prepare.label_theme = MagicMock()
+
+        self.gdm_installer.compile(themes=[theme_prepare], hue=0, color="red", sat=None)
+
+        theme_prepare.label_theme.assert_called_once()
+
+    def test_compile_calls_removes_keywords_and_properties_and_prepends_source_styles(self):
+        theme_prepare = MagicMock()
+        theme_prepare.remove_keywords = MagicMock()
+        theme_prepare.remove_properties = MagicMock()
+        theme_prepare.prepend_source_styles = MagicMock()
+
+        self.gdm_installer.compile(themes=[theme_prepare], hue=0, color="red", sat=None)
+
+        theme_prepare.remove_keywords.assert_called_once()
+        theme_prepare.remove_properties.assert_called_once()
+        theme_prepare.prepend_source_styles.assert_called_once()
+
+    def test_compile_installs_themes_with_correct_parameters(self):
+        theme_prepare = MagicMock()
+        theme_prepare.install = MagicMock()
+        themes = [theme_prepare]
+        hue = 0
+        color = "red"
+        sat = None
+
+        self.gdm_installer.compile(themes, hue, color, sat)
+
+        theme_prepare.install.assert_called_once()
+        theme_prepare.install.assert_called_with(hue, color, sat, destination=self.temp_folder)
+
+    def test_compile_calls_gresource_compile(self):
+        self.gdm_installer.compile([], 0, "red", None)
+
+        self.gresource.compile.assert_called_once()
+
+    def test_backup_calls_gresource_backup(self):
+        self.gdm_installer.backup()
+
+        self.gresource.backup.assert_called_once()
+
+    def test_install_calls_gresource_move_and_alternatives_updater_install_and_set(self):
+        self.gdm_installer.install()
+
+        self.gresource.move.assert_called_once()
+        self.alternatives_updater.install_and_set.assert_called_once()
\ No newline at end of file
diff --git a/tests/utils/global_theme/test_gdm_preparer.py b/tests/utils/global_theme/test_gdm_preparer.py
new file mode 100644
index 0000000..99748ce
--- /dev/null
+++ b/tests/utils/global_theme/test_gdm_preparer.py
@@ -0,0 +1,124 @@
+import os
+import shutil
+import unittest
+from unittest.mock import MagicMock, patch
+
+from scripts import config
+from scripts.types.theme_base import ThemeBase
+from scripts.utils.global_theme.gdm_preparer import GDMThemePreparer
+
+
+class DummyTheme(ThemeBase):
+    def __init__(self):
+        super().__init__()
+        self.temp_folder = None
+        self.main_styles = None
+
+    def prepare(self):
+        pass
+
+    def install(self, hue: int, name: str, sat: float | None = None):
+        pass
+
+
+class TestGDMThemePreparer(unittest.TestCase):
+    def setUp(self):
+        self.temp_folder = os.path.join(config.temp_tests_folder, "gdm_preparer")
+
+        self.gresource = self._mock_gresource(self.temp_folder)
+        self.theme_builder = self._mock_builder()
+
+        self.mock_logger = MagicMock()
+        self.logger_factory = MagicMock()
+        self.logger_factory.create_logger.return_value = self.mock_logger
+
+        self.preparer = GDMThemePreparer(
+            temp_folder=self.temp_folder,
+            default_mode="light",
+            is_filled=True,
+            gresource=self.gresource,
+            theme_builder=self.theme_builder,
+            logger_factory=self.logger_factory,
+            files_labeler_factory=MagicMock(),
+        )
+
+    @staticmethod
+    def _mock_gresource(temp_folder):
+        gresource = MagicMock()
+        gresource.temp_folder = temp_folder
+        gresource.extract = MagicMock()
+        gresource.use_backup_gresource = MagicMock()
+        return gresource
+
+    @staticmethod
+    def _mock_builder():
+        theme_builder = MagicMock()
+        theme_builder.with_temp_folder.return_value = theme_builder
+        theme_builder.with_theme_name.return_value = theme_builder
+        theme_builder.with_mode.return_value = theme_builder
+        theme_builder.filled.return_value = theme_builder
+        theme_builder.with_logger_factory.return_value = theme_builder
+        theme_builder.with_reset_dependencies.return_value = theme_builder
+        theme_builder.build.return_value = DummyTheme()
+        return theme_builder
+
+    def tearDown(self):
+        shutil.rmtree(self.temp_folder, ignore_errors=True)
+
+    def test_use_backup_as_source(self):
+        self.preparer.use_backup_as_source()
+
+        self.gresource.use_backup_gresource.assert_called_once()
+
+    @patch("os.listdir")
+    def test_preparer_extracts_gresource(self, mock_listdir):
+        mock_listdir.return_value = ["gnome-shell.css"]
+
+        self.preparer.prepare()
+
+        self.gresource.extract.assert_called_once()
+
+    @patch("os.listdir")
+    def test_preparer_scans_correct_directory(self, mock_listdir):
+        mock_listdir.return_value = ["gnome-shell.css"]
+
+        self.preparer.prepare()
+
+        mock_listdir.assert_called_once_with(self.gresource.temp_folder)
+
+    @patch("os.listdir")
+    def test_preparer_filters_valid_css_files(self, mock_listdir):
+        valid_files = ["gnome-shell-dark.css", "gnome-shell-light.css", "gnome-shell.css"]
+        invalid_files = ["other.css", "readme.txt"]
+        mock_listdir.return_value = valid_files + invalid_files
+
+        themes = self.preparer.prepare()
+
+        self.assertEqual(len(themes), len(valid_files))
+
+    @patch("os.listdir")
+    def test_preparer_assigns_correct_labels(self, mock_listdir):
+        test_files = ["gnome-shell-dark.css", "gnome-shell-light.css", "gnome-shell.css"]
+        mock_listdir.return_value = test_files
+
+        themes = self.preparer.prepare()
+
+        expected_labels = {
+            "gnome-shell-dark.css": "dark",
+            "gnome-shell-light.css": "light",
+            "gnome-shell.css": "light"  # Uses default_mode
+        }
+
+        for theme_obj in themes:
+            file_name = os.path.basename(theme_obj.theme_file)
+            self.assertEqual(theme_obj.label, expected_labels[file_name])
+
+    @patch("os.listdir")
+    def test_preparer_configures_theme_builder_correctly(self, mock_listdir):
+        mock_listdir.return_value = ["gnome-shell-dark.css", "gnome-shell.css"]
+
+        self.preparer.prepare()
+
+        self.theme_builder.with_theme_name.assert_any_call("gnome-shell-dark")
+        self.theme_builder.with_theme_name.assert_any_call("gnome-shell")
+
diff --git a/tests/utils/global_theme/test_gdm_remover.py b/tests/utils/global_theme/test_gdm_remover.py
new file mode 100644
index 0000000..04b2d07
--- /dev/null
+++ b/tests/utils/global_theme/test_gdm_remover.py
@@ -0,0 +1,44 @@
+from unittest import TestCase
+from unittest.mock import MagicMock
+
+from scripts.utils.global_theme.gdm_remover import GDMThemeRemover
+from scripts.utils.gresource import GresourceBackupNotFoundError
+
+
+class GDMRemoverTestCase(TestCase):
+    def setUp(self):
+        self.gresource = MagicMock()
+        self.alternatives_updater = MagicMock()
+        self.logger = MagicMock()
+        self.logger_factory = MagicMock(return_value=self.logger)
+
+        self.remover = GDMThemeRemover(
+            gresource=self.gresource,
+            alternatives_updater=self.alternatives_updater,
+            logger_factory=self.logger_factory
+        )
+
+        self.remover.remover_logger = MagicMock()
+
+    def test_remove_logs_start_message(self):
+        self.remover.remove()
+
+        self.remover.remover_logger.start_removing.assert_called_once()
+
+    def test_remove_calls_gresource_restore_and_alternatives_remove(self):
+        self.remover.remove()
+
+        self.gresource.restore.assert_called_once()
+        self.alternatives_updater.remove.assert_called_once()
+
+    def test_remove_logs_success_message(self):
+        self.remover.remove()
+
+        self.remover.remover_logger.success_removing.assert_called_once()
+
+    def test_remove_logs_error_message_when_backup_not_found(self):
+        self.gresource.restore.side_effect = GresourceBackupNotFoundError()
+
+        self.remover.remove()
+
+        self.remover.remover_logger.error_removing.assert_called_once()
\ No newline at end of file
diff --git a/tests/utils/global_theme/test_gdm_theme_prepare.py b/tests/utils/global_theme/test_gdm_theme_prepare.py
new file mode 100644
index 0000000..cc0fac1
--- /dev/null
+++ b/tests/utils/global_theme/test_gdm_theme_prepare.py
@@ -0,0 +1,118 @@
+import os.path
+import shutil
+from unittest import TestCase
+from unittest.mock import MagicMock
+
+from scripts import config
+from scripts.utils.global_theme.gdm_theme_prepare import GDMThemePrepare
+from ..._helpers import create_dummy_file, try_remove_file
+
+
+class GDMThemePrepareTestCase(TestCase):
+    def setUp(self):
+        self.temp_folder = os.path.join(config.temp_tests_folder, "gdm_theme_prepare")
+        self.main_styles = os.path.join(self.temp_folder, "gnome-shell.css")
+        self.theme = MagicMock()
+        self.theme.add_to_start.return_value = None
+        self.theme.temp_folder = self.temp_folder
+        self.theme.main_styles = self.main_styles
+
+        self.main_styles_destination = os.path.join(self.temp_folder, "gnome-shell-result.css")
+        create_dummy_file(self.main_styles_destination, "body { background-color: #000; }")
+
+        self.files_labeler = MagicMock()
+
+        self.theme_prepare = GDMThemePrepare(
+            theme=self.theme,
+            theme_file=self.main_styles_destination,
+            label=None,
+            files_labeler=self.files_labeler,
+        )
+
+    def tearDown(self):
+        shutil.rmtree(self.temp_folder, ignore_errors=True)
+
+    def test_label_files_calls_labeler(self):
+        self.theme_prepare.label = "dark"
+
+        self.theme_prepare.label_theme()
+
+        self.files_labeler.append_label.assert_called_once_with("dark")
+
+    def test_label_files_raises_value_error_if_label_none(self):
+        self.theme_prepare.label = None
+
+        with self.assertRaises(ValueError):
+            self.theme_prepare.label_theme()
+
+    def test_remove_keywords_removes_destination_keywords(self):
+        try_remove_file(self.main_styles_destination)
+        expected_content = "body { background-color: #000; }"
+        create_dummy_file(self.main_styles_destination, "body {keyword1 background-color: #000 !important; }")
+        keywords = ["keyword1", " !important"]
+
+        self.theme_prepare.remove_keywords(*keywords)
+
+        with open(self.main_styles_destination, 'r') as file:
+            content = file.read()
+            self.assertEqual(content, expected_content)
+        try_remove_file(self.main_styles_destination)
+
+    def test_remove_properties_removes_destination_properties(self):
+        try_remove_file(self.main_styles_destination)
+        expected_content = "body {\n}\n"
+        create_dummy_file(self.main_styles_destination, "body {\nbackground-color: #000;\n}")
+        properties = ["background-color"]
+
+        self.theme_prepare.remove_properties(*properties)
+
+        with open(self.main_styles_destination, 'r') as file:
+            actual_content = file.read()
+            self.assertEqual(expected_content, actual_content)
+        try_remove_file(self.main_styles_destination)
+
+    def test_remove_properties_removes_one_line_properties(self):
+        try_remove_file(self.main_styles_destination)
+        expected_content = ""
+        create_dummy_file(self.main_styles_destination, "body { background-color: #000; }")
+        properties = ["background-color"]
+
+        self.theme_prepare.remove_properties(*properties)
+
+        with open(self.main_styles_destination, 'r') as file:
+            actual_content = file.read()
+            self.assertEqual(expected_content, actual_content)
+        try_remove_file(self.main_styles_destination)
+
+    def test_prepend_source_styles_prepends_destination_styles(self):
+        try_remove_file(self.main_styles_destination)
+        expected_content = "body { background-color: #000; }\n"
+        create_dummy_file(self.main_styles_destination, "body { background-color: #000; }")
+
+        self.theme_prepare.prepend_source_styles("")
+
+        called_content: str = self.theme.add_to_start.call_args[0][0]
+        self.assertTrue(called_content.startswith(expected_content))
+        try_remove_file(self.main_styles_destination)
+
+    def test_prepend_source_styles_adds_trigger(self):
+        try_remove_file(self.main_styles_destination)
+        expected_content = "\ntrigger\n"
+        create_dummy_file(self.main_styles_destination)
+        trigger = "trigger"
+
+        self.theme_prepare.prepend_source_styles(trigger)
+
+        called_content: str = self.theme.add_to_start.call_args[0][0]
+        self.assertTrue(expected_content in called_content)
+        try_remove_file(self.main_styles_destination)
+
+    def test_install_passes_arguments_to_theme(self):
+        hue = 0
+        color = "#000000"
+        sat = 100
+        destination = os.path.join(self.temp_folder, "destination")
+
+        self.theme_prepare.install(hue, color, sat, destination)
+
+        self.theme.install.assert_called_once_with(hue, color, sat, destination=destination)
\ No newline at end of file
diff --git a/tests/utils/global_theme/test_ubuntu_gdm_update_alternatives.py b/tests/utils/global_theme/test_ubuntu_gdm_update_alternatives.py
new file mode 100644
index 0000000..98b5f3e
--- /dev/null
+++ b/tests/utils/global_theme/test_ubuntu_gdm_update_alternatives.py
@@ -0,0 +1,47 @@
+from unittest import TestCase
+from unittest.mock import MagicMock
+
+from scripts.utils.alternatives_updater import AlternativesUpdater
+from scripts.utils.global_theme.ubuntu_alternatives_updater import UbuntuGDMAlternativesUpdater
+
+
+class UbuntuGDMUpdateAlternativesTestCase(TestCase):
+    def setUp(self):
+        self.updater = MagicMock(spec=AlternativesUpdater)
+        self.ubuntu_updater = UbuntuGDMAlternativesUpdater(
+            alternatives_updater=self.updater
+        )
+
+    def test_custom_destination_updates_correctly(self):
+        custom_destination_dir = "/custom/path"
+        custom_destination_file = "custom_file.gresource"
+
+        self.ubuntu_updater.with_custom_destination(
+            custom_destination_dir, custom_destination_file
+        )
+
+        self.assertEqual(
+            self.ubuntu_updater.destination_dir, custom_destination_dir
+        )
+        self.assertEqual(
+            self.ubuntu_updater.destination_file, custom_destination_file
+        )
+
+    def test_install_and_set_calls_updater_correctly(self):
+        priority = 100
+        self.ubuntu_updater.install_and_set(priority)
+
+        self.updater.install_and_set.assert_called_once_with(
+            link=self.ubuntu_updater.ubuntu_gresource_path,
+            name=self.ubuntu_updater.ubuntu_gresource_link_name,
+            path=self.ubuntu_updater.gnome_gresource_path,
+            priority=priority
+        )
+
+    def test_remove_calls_updater_correctly(self):
+        self.ubuntu_updater.remove()
+
+        self.updater.remove.assert_called_once_with(
+            name=self.ubuntu_updater.ubuntu_gresource_link_name,
+            path=self.ubuntu_updater.gnome_gresource_path
+        )
\ No newline at end of file
diff --git a/tests/utils/test_files_labeler.py b/tests/utils/test_files_labeler.py
new file mode 100644
index 0000000..8c024a1
--- /dev/null
+++ b/tests/utils/test_files_labeler.py
@@ -0,0 +1,57 @@
+import os.path
+import shutil
+from unittest import TestCase
+
+from scripts import config
+from scripts.utils.files_labeler import FilesLabelerFactoryImpl
+from .._helpers import create_dummy_file
+
+
+class FilesLabelerTestCase(TestCase):
+    def setUp(self):
+        self.temp_folder = os.path.join(config.temp_tests_folder, "labeler")
+
+        self.files = ["file1.svg", "file2.png", "file3.svg"]
+        self.styles_file = os.path.join(self.temp_folder, "styles-test.css")  # styles files are already labeled
+        self.original_styles_content = f"body {{ background: url('./{self.files[0]}'); }}"
+
+        self.factory = FilesLabelerFactoryImpl()
+
+    def _generate_test_files(self):
+        self.tearDown()
+
+        for filename in self.files:
+            create_dummy_file(os.path.join(self.temp_folder, filename))
+
+        create_dummy_file(self.styles_file, self.original_styles_content)
+
+    def tearDown(self):
+        shutil.rmtree(self.temp_folder, ignore_errors=True)
+
+    def test_append_label_correctly_labels_files(self):
+        self._generate_test_files()
+        label = "test"
+        labeled_files = [(f, f.replace(".", f"-{label}.")) for f in self.files]
+        labeler = self.factory.create(self.temp_folder)
+
+        labeler.append_label(label)
+
+        for original, labeled in labeled_files:
+            labeled_path = os.path.join(self.temp_folder, labeled)
+            original_path = os.path.join(self.temp_folder, original)
+            self.assertTrue(os.path.exists(labeled_path))
+            self.assertFalse(os.path.exists(original_path))
+
+    def test_append_label_correctly_updates_references(self):
+        self._generate_test_files()
+        label = "test"
+        replaced_file = self.files[0].replace('.', f'-{label}.')
+        expected_content = f"body {{ background: url('./{replaced_file}'); }}"
+        labeler = self.factory.create(self.temp_folder, self.styles_file)
+
+        labeler.append_label(label)
+
+        with open(self.styles_file, 'r') as file:
+            actual_content = file.read()
+            self.assertNotEqual(actual_content, self.original_styles_content)
+            self.assertEqual(actual_content, expected_content)
\ No newline at end of file