diff --git a/craft_application/pytest_plugin.py b/craft_application/pytest_plugin.py
new file mode 100644
index 00000000..9ba4f0f2
--- /dev/null
+++ b/craft_application/pytest_plugin.py
@@ -0,0 +1,145 @@
+# Copyright 2025 Canonical Ltd.
+#
+# This program is free software: you can redistribute it and/or modify it
+# under the terms of the GNU Lesser General Public License version 3, as
+# published by the Free Software Foundation.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranties of MERCHANTABILITY,
+# SATISFACTORY QUALITY, or FITNESS FOR A PARTICULAR PURPOSE.
+# See the GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License along
+# with this program.  If not, see <http://www.gnu.org/licenses/>.
+"""A pytest plugin for assisting in testing apps that use craft-application."""
+
+from __future__ import annotations
+
+import os
+import pathlib
+import platform
+from collections.abc import Iterator
+from typing import TYPE_CHECKING
+
+import craft_platforms
+import pytest
+
+from craft_application import util
+from craft_application.util import platforms
+
+if TYPE_CHECKING:
+    from pyfakefs.fake_filesystem import FakeFilesystem
+
+
+@pytest.fixture(autouse=True, scope="session")
+def debug_mode() -> None:
+    """Ensure that the application is in debug mode, raising exceptions from run().
+
+    This fixture is automatically used. To disable debug mode for specific tests that
+    require it, use the :py:func:`production_mode` fixture.
+    """
+    os.environ["CRAFT_DEBUG"] = "1"
+
+
+@pytest.fixture
+def production_mode(monkeypatch: pytest.MonkeyPatch) -> None:
+    """Put the application into production mode.
+
+    This fixture puts the application into production mode rather than debug mode.
+    It should only be used if the application needs to test behaviour that differs
+    between debug mode and production mode.
+    """
+    monkeypatch.setenv("CRAFT_DEBUG", "0")
+
+
+@pytest.fixture
+def managed_mode(monkeypatch: pytest.MonkeyPatch) -> None:
+    """Tell the application it's running in managed mode.
+
+    This fixture sets up the application's environment so that it appears to be using
+    managed mode. Useful for testing behaviours that only occur in managed mode.
+    """
+    if os.getenv("CRAFT_BUILD_ENVIRONMENT") == "host":
+        raise LookupError("Managed mode and destructive mode are mutually exclusive.")
+    monkeypatch.setenv(platforms.ENVIRONMENT_CRAFT_MANAGED_MODE, "1")
+
+
+@pytest.fixture
+def destructive_mode(monkeypatch: pytest.MonkeyPatch) -> None:
+    """Tell the application it's running in destructive mode.
+
+    This fixture sets up the application's environment so that it appears to be running
+    in destructive mode with the "CRAFT_BUILD_ENVIRONMENT" environment variable set.
+    """
+    if os.getenv(platforms.ENVIRONMENT_CRAFT_MANAGED_MODE):
+        raise LookupError("Destructive mode and managed mode are mutually exclusive.")
+    monkeypatch.setenv("CRAFT_BUILD_ENVIRONMENT", "host")
+
+
+def _optional_pyfakefs(request: pytest.FixtureRequest) -> FakeFilesystem | None:
+    """Get pyfakefs if it's in use by the fixture request."""
+    if {"fs", "fs_class", "fs_module", "fs_session"} & set(request.fixturenames):
+        try:
+            from pyfakefs.fake_filesystem import FakeFilesystem
+
+            fs = request.getfixturevalue("fs")
+            if isinstance(fs, FakeFilesystem):
+                return fs
+        except ImportError:
+            # pyfakefs isn't installed,so this fixture means something else.
+            pass
+    return None
+
+
+@pytest.fixture(params=craft_platforms.DebianArchitecture)
+def fake_host_architecture(
+    request: pytest.FixtureRequest, monkeypatch: pytest.MonkeyPatch
+) -> Iterator[craft_platforms.DebianArchitecture]:
+    """Run this test as though running on each supported architecture.
+
+    This parametrized fixture provides architecture values for all supported
+    architectures, simulating as though the application is running on that architecture.
+    This fixture is limited to setting the architecture within this python process.
+    """
+    arch: craft_platforms.DebianArchitecture = request.param
+    platform_arch = arch.to_platform_arch()
+    real_uname = platform.uname()
+    monkeypatch.setattr(
+        "platform.uname", lambda: real_uname._replace(machine=platform_arch)
+    )
+    util.get_host_architecture.cache_clear()
+    yield arch
+    util.get_host_architecture.cache_clear()
+
+
+@pytest.fixture
+def project_path(request: pytest.FixtureRequest) -> pathlib.Path:
+    """Get a temporary path for a project.
+
+    This fixture creates a temporary path for a project. It does not create any files
+    in the project directory, but rather provides a pristine project directory without
+    the need to worry about other fixtures loading things.
+
+    This fixture can be used with or without pyfakefs.
+    """
+    if fs := _optional_pyfakefs(request):
+        project_path = pathlib.Path("/test/project")
+        fs.create_dir(project_path)  # type: ignore[reportUnknownMemberType]
+        return project_path
+    tmp_path: pathlib.Path = request.getfixturevalue("tmp_path")
+    path = tmp_path / "project"
+    path.mkdir()
+    return path
+
+
+@pytest.fixture
+def in_project_path(
+    project_path: pathlib.Path, monkeypatch: pytest.MonkeyPatch
+) -> pathlib.Path:
+    """Run the test inside the project path.
+
+    Changes the working directory of the test to use the project path.
+    Best to use with ``pytest.mark.usefixtures``
+    """
+    monkeypatch.chdir(project_path)
+    return project_path
diff --git a/docs/conf.py b/docs/conf.py
index 527df7a9..aac870ac 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -39,6 +39,7 @@
 
 extensions = [
     "canonical_sphinx",
+    "sphinx.ext.autodoc",
 ]
 # endregion
 
diff --git a/docs/reference/changelog.rst b/docs/reference/changelog.rst
index fc026206..be2648b8 100644
--- a/docs/reference/changelog.rst
+++ b/docs/reference/changelog.rst
@@ -4,6 +4,23 @@
 Changelog
 *********
 
+5.0.0 (2025-Mon-DD)
+-------------------
+
+Testing
+=======
+
+- A new :doc:`pytest-plugin` with a fixture that enables production mode for the
+  application if a test requires it.
+
+Breaking changes
+================
+
+- The pytest plugin includes an auto-used fixture that puts the app into debug mode
+  by default for tests.
+
+For a complete list of commits, check out the `5.0.0`_ release on GitHub.
+
 4.9.1 (2025-Feb-12)
 -------------------
 
@@ -23,7 +40,7 @@ Application
 ===========
 
 - Add a feature to allow `Python plugins
-  https://packaging.python.org/en/latest/guides/creating-and-discovering-plugins/>`_
+  <https://packaging.python.org/en/latest/guides/creating-and-discovering-plugins/>`_
   to extend or modify the behaviour of applications that use craft-application as a
   framework. The plugin packages must be installed in the same virtual environment
   as the application.
@@ -588,3 +605,4 @@ For a complete list of commits, check out the `2.7.0`_ release on GitHub.
 .. _4.8.3: https://github.com/canonical/craft-application/releases/tag/4.8.3
 .. _4.9.0: https://github.com/canonical/craft-application/releases/tag/4.9.0
 .. _4.9.1: https://github.com/canonical/craft-application/releases/tag/4.9.1
+.. _5.0.0: https://github.com/canonical/craft-application/releases/tag/5.0.0
diff --git a/docs/reference/index.rst b/docs/reference/index.rst
index 1e7796c6..e9fa0028 100644
--- a/docs/reference/index.rst
+++ b/docs/reference/index.rst
@@ -9,6 +9,7 @@ Reference
    changelog
    environment-variables
    platforms
+   pytest-plugin
 
 Indices and tables
 ==================
diff --git a/docs/reference/pytest-plugin.rst b/docs/reference/pytest-plugin.rst
new file mode 100644
index 00000000..8b87cd3d
--- /dev/null
+++ b/docs/reference/pytest-plugin.rst
@@ -0,0 +1,38 @@
+.. py:module:: craft_application.pytest_plugin
+
+pytest plugin
+=============
+
+craft-application includes a `pytest`_ plugin to help ease the testing of apps that use
+it as a framework.
+
+By default, this plugin sets the application into debug mode, meaning the
+:py:meth:`~craft_application.Application.run()` method will re-raise generic exceptions.
+
+
+Fixtures
+--------
+
+.. autofunction:: production_mode
+
+.. autofunction:: managed_mode
+
+.. autofunction:: destructive_mode
+
+.. autofunction:: fake_host_architecture
+
+.. autofunction:: project_path
+
+.. autofunction:: in_project_path
+
+Auto-used fixtures
+~~~~~~~~~~~~~~~~~~
+
+Some fixtures are automatically enabled for tests, changing the default behaviour of
+applications during the testing process. This is kept to a minimum, but is done when
+the standard behaviour could cause subtle testing issues.
+
+.. autofunction:: debug_mode
+
+
+.. _pytest: https://docs.pytest.org
diff --git a/pyproject.toml b/pyproject.toml
index b3ee7265..150a2320 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -42,7 +42,8 @@ classifiers = [
 ]
 requires-python = ">=3.10"
 
-[project.scripts]
+[project.entry-points.pytest11]
+craft_application = "craft_application.pytest_plugin"
 
 [project.optional-dependencies]
 remote = [
diff --git a/tests/conftest.py b/tests/conftest.py
index b482e878..5bf2ec57 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -103,18 +103,6 @@ def fake_config_model() -> type[FakeConfigModel]:
     return FakeConfigModel
 
 
-@pytest.fixture(scope="session")
-def default_app_metadata(fake_config_model) -> craft_application.AppMetadata:
-    with pytest.MonkeyPatch.context() as m:
-        m.setattr(metadata, "version", lambda _: "3.14159")
-        return craft_application.AppMetadata(
-            "testcraft",
-            "A fake app for testing craft-application",
-            source_ignore_patterns=["*.snap", "*.charm", "*.starcraft"],
-            ConfigModel=fake_config_model,
-        )
-
-
 @pytest.fixture
 def app_metadata(features, fake_config_model) -> craft_application.AppMetadata:
     with pytest.MonkeyPatch.context() as m:
@@ -124,24 +112,11 @@ def app_metadata(features, fake_config_model) -> craft_application.AppMetadata:
             "A fake app for testing craft-application",
             source_ignore_patterns=["*.snap", "*.charm", "*.starcraft"],
             features=craft_application.AppFeatures(**features),
-            docs_url="www.testcraft.example/docs/{version}",
+            docs_url="http://testcraft.example/docs/{version}",
             ConfigModel=fake_config_model,
         )
 
 
-@pytest.fixture
-def app_metadata_docs(features) -> craft_application.AppMetadata:
-    with pytest.MonkeyPatch.context() as m:
-        m.setattr(metadata, "version", lambda _: "3.14159")
-        return craft_application.AppMetadata(
-            "testcraft",
-            "A fake app for testing craft-application",
-            docs_url="http://testcraft.example",
-            source_ignore_patterns=["*.snap", "*.charm", "*.starcraft"],
-            features=craft_application.AppFeatures(**features),
-        )
-
-
 @pytest.fixture
 def fake_project() -> models.Project:
     arch = util.get_host_architecture()
diff --git a/tests/integration/conftest.py b/tests/integration/conftest.py
index 7ec1b8d8..4ee6785e 100644
--- a/tests/integration/conftest.py
+++ b/tests/integration/conftest.py
@@ -57,10 +57,10 @@ def provider_service(app_metadata, fake_project, fake_build_plan, fake_services)
     )
 
 
-@pytest.fixture(scope="session")
-def anonymous_remote_build_service(default_app_metadata):
+@pytest.fixture
+def anonymous_remote_build_service(app_metadata):
     """Provider service with install snap disabled for integration tests"""
-    service = remotebuild.RemoteBuildService(default_app_metadata, services=mock.Mock())
+    service = remotebuild.RemoteBuildService(app_metadata, services=mock.Mock())
     service.lp = launchpad.Launchpad.anonymous("testcraft")
     return service
 
diff --git a/tests/integration/test_application.py b/tests/integration/test_application.py
index 6da2950d..061b2c1e 100644
--- a/tests/integration/test_application.py
+++ b/tests/integration/test_application.py
@@ -84,7 +84,7 @@ def app(create_app):
 
 For more information about a command, run 'testcraft help <command>'.
 For a summary of all commands, run 'testcraft help --all'.
-For more information about testcraft, check out: www.testcraft.example/docs/3.14159
+For more information about testcraft, check out: http://testcraft.example/docs/3.14159
 
 """
 INVALID_COMMAND = """\
@@ -296,7 +296,7 @@ def test_get_command_help(monkeypatch, emitter, capsys, app, cmd, help_param):
     assert f"testcraft {cmd} [options]" in stderr
     assert stderr.endswith(
         "For more information, check out: "
-        f"www.testcraft.example/docs/3.14159/reference/commands/{cmd}\n\n"
+        f"http://testcraft.example/docs/3.14159/reference/commands/{cmd}\n\n"
     )
 
 
@@ -503,7 +503,8 @@ def test_runtime_error_logging(monkeypatch, tmp_path, create_app, mocker):
     monkeypatch.setattr("sys.argv", ["testcraft", "pack", "--destructive-mode"])
     app = create_app()
 
-    app.run()
+    with pytest.raises(RuntimeError):
+        app.run()
 
     log_contents = craft_cli.emit._log_filepath.read_text()
 
diff --git a/tests/unit/conftest.py b/tests/unit/conftest.py
index 5de73f33..316fb822 100644
--- a/tests/unit/conftest.py
+++ b/tests/unit/conftest.py
@@ -22,7 +22,7 @@
 import pytest
 import pytest_mock
 
-from craft_application import git, services, util
+from craft_application import git, services
 from craft_application.services import service_factory
 
 BASIC_PROJECT_YAML = """
@@ -37,12 +37,6 @@
 """
 
 
-@pytest.fixture(params=["amd64", "arm64", "riscv64"])
-def fake_host_architecture(monkeypatch, request) -> str:
-    monkeypatch.setattr(util, "get_host_architecture", lambda: request.param)
-    return request.param
-
-
 @pytest.fixture
 def provider_service(
     app_metadata, fake_project, fake_build_plan, fake_services, tmp_path
@@ -110,11 +104,8 @@ def expected_git_command(
 
 
 @pytest.fixture
-def fake_project_file(monkeypatch, tmp_path):
-    project_dir = tmp_path / "project"
-    project_dir.mkdir()
-    project_path = project_dir / "testcraft.yaml"
-    project_path.write_text(BASIC_PROJECT_YAML)
-    monkeypatch.chdir(project_dir)
-
-    return project_path
+def fake_project_file(in_project_path):
+    project_file = in_project_path / "testcraft.yaml"
+    project_file.write_text(BASIC_PROJECT_YAML)
+
+    return project_file
diff --git a/tests/unit/services/test_config.py b/tests/unit/services/test_config.py
index c181b012..4b8ef1b8 100644
--- a/tests/unit/services/test_config.py
+++ b/tests/unit/services/test_config.py
@@ -27,7 +27,7 @@
 import pytest
 import pytest_subprocess
 import snaphelpers
-from hypothesis import given, strategies
+from hypothesis import HealthCheck, given, settings, strategies
 
 import craft_application
 from craft_application import launchpad
@@ -64,18 +64,18 @@
 TEST_ENTRY_VALUES = CRAFT_APPLICATION_TEST_ENTRY_VALUES + APP_SPECIFIC_TEST_ENTRY_VALUES
 
 
-@pytest.fixture(scope="module")
-def app_environment_handler(default_app_metadata) -> config.AppEnvironmentHandler:
-    return config.AppEnvironmentHandler(default_app_metadata)
+@pytest.fixture
+def app_environment_handler(app_metadata) -> config.AppEnvironmentHandler:
+    return config.AppEnvironmentHandler(app_metadata)
 
 
-@pytest.fixture(scope="module")
-def craft_environment_handler(default_app_metadata) -> config.CraftEnvironmentHandler:
-    return config.CraftEnvironmentHandler(default_app_metadata)
+@pytest.fixture
+def craft_environment_handler(app_metadata) -> config.CraftEnvironmentHandler:
+    return config.CraftEnvironmentHandler(app_metadata)
 
 
-@pytest.fixture(scope="module")
-def snap_config_handler(default_app_metadata) -> Iterator[config.SnapConfigHandler]:
+@pytest.fixture
+def snap_config_handler(app_metadata) -> Iterator[config.SnapConfigHandler]:
     with pytest.MonkeyPatch.context() as monkeypatch:
         monkeypatch.setenv("SNAP", "/snap/testcraft/x1")
         monkeypatch.setenv("SNAP_COMMON", "/")
@@ -85,12 +85,12 @@ def snap_config_handler(default_app_metadata) -> Iterator[config.SnapConfigHandl
         monkeypatch.setenv("SNAP_USER_DATA", "/")
         monkeypatch.setenv("SNAP_INSTANCE_NAME", "testcraft")
         monkeypatch.setenv("SNAP_INSTANCE_KEY", "")
-        yield config.SnapConfigHandler(default_app_metadata)
+        yield config.SnapConfigHandler(app_metadata)
 
 
-@pytest.fixture(scope="module")
-def default_config_handler(default_app_metadata) -> config.DefaultConfigHandler:
-    return config.DefaultConfigHandler(default_app_metadata)
+@pytest.fixture
+def default_config_handler(app_metadata) -> config.DefaultConfigHandler:
+    return config.DefaultConfigHandler(app_metadata)
 
 
 @given(
@@ -99,6 +99,7 @@ def default_config_handler(default_app_metadata) -> config.DefaultConfigHandler:
         alphabet=strategies.characters(categories=["L", "M", "N", "P", "S", "Z"])
     ),
 )
+@settings(suppress_health_check=[HealthCheck.function_scoped_fixture])
 def test_app_environment_handler(app_environment_handler, item: str, content: str):
     with pytest.MonkeyPatch.context() as monkeypatch:
         monkeypatch.setenv(f"TESTCRAFT_{item.upper()}", content)
@@ -112,6 +113,7 @@ def test_app_environment_handler(app_environment_handler, item: str, content: st
         alphabet=strategies.characters(categories=["L", "M", "N", "P", "S", "Z"])
     ),
 )
+@settings(suppress_health_check=[HealthCheck.function_scoped_fixture])
 def test_craft_environment_handler(craft_environment_handler, item: str, content: str):
     with pytest.MonkeyPatch.context() as monkeypatch:
         monkeypatch.setenv(f"CRAFT_{item.upper()}", content)
@@ -149,23 +151,23 @@ def test_craft_environment_handler_error(
         ),
     ],
 )
-def test_snap_config_handler_create_error(mocker, default_app_metadata, error):
+def test_snap_config_handler_create_error(mocker, app_metadata, error):
     mocker.patch("snaphelpers.is_snap", return_value=True)
     mock_snap_config = mocker.patch(
         "snaphelpers.SnapConfig",
         side_effect=error,
     )
     with pytest.raises(OSError, match="Not running as a snap."):
-        config.SnapConfigHandler(default_app_metadata)
+        config.SnapConfigHandler(app_metadata)
 
     mock_snap_config.assert_called_once_with()
 
 
-def test_snap_config_handler_not_snap(mocker, default_app_metadata):
+def test_snap_config_handler_not_snap(mocker, app_metadata):
     mock_is_snap = mocker.patch("snaphelpers.is_snap", return_value=False)
 
     with pytest.raises(OSError, match="Not running as a snap."):
-        config.SnapConfigHandler(default_app_metadata)
+        config.SnapConfigHandler(app_metadata)
 
     mock_is_snap.asssert_called_once_with()
 
@@ -176,6 +178,7 @@ def test_snap_config_handler_not_snap(mocker, default_app_metadata):
         alphabet=strategies.characters(categories=["L", "M", "N", "P", "S", "Z"])
     ),
 )
+@settings(suppress_health_check=[HealthCheck.function_scoped_fixture])
 def test_snap_config_handler(snap_config_handler, item: str, content: str):
     snap_item = item.replace("_", "-")
     with (
diff --git a/tests/unit/test_application.py b/tests/unit/test_application.py
index 898f1f75..dbc51d06 100644
--- a/tests/unit/test_application.py
+++ b/tests/unit/test_application.py
@@ -1048,7 +1048,7 @@ def test_run_error(
                 """\
                 Failed to run the build script for part 'foo'.
                 Recommended resolution: Check the build output and verify the project can work with the 'python' plugin.
-                For more information, check out: http://testcraft.example/reference/plugins.html
+                For more information, check out: http://testcraft.example/docs/3.14159/reference/plugins.html
                 Full execution log:"""
             ),
         ),
@@ -1058,14 +1058,14 @@ def test_run_error_with_docs_url(
     monkeypatch,
     capsys,
     mock_dispatcher,
-    app_metadata_docs,
+    app_metadata,
     fake_services,
     fake_project,
     error,
     return_code,
     error_msg,
 ):
-    app = FakeApplication(app_metadata_docs, fake_services)
+    app = FakeApplication(app_metadata, fake_services)
     app.set_project(fake_project)
     mock_dispatcher.load_command.side_effect = error
     mock_dispatcher.pre_parse_args.return_value = {}
@@ -1077,7 +1077,7 @@ def test_run_error_with_docs_url(
 
 
 @pytest.mark.parametrize("error", [KeyError(), ValueError(), Exception()])
-@pytest.mark.usefixtures("emitter")
+@pytest.mark.usefixtures("emitter", "debug_mode")
 def test_run_error_debug(monkeypatch, mock_dispatcher, app, fake_project, error):
     app.set_project(fake_project)
     mock_dispatcher.load_command.side_effect = error
@@ -1335,41 +1335,39 @@ def test_work_dir_project_managed(monkeypatch, app_metadata, fake_services):
 
 
 @pytest.fixture
-def environment_project(monkeypatch, tmp_path):
-    project_dir = tmp_path / "project"
-    project_dir.mkdir()
-    project_path = project_dir / "testcraft.yaml"
-    project_path.write_text(
+def environment_project(in_project_path):
+    project_file = in_project_path / "testcraft.yaml"
+    project_file.write_text(
         dedent(
+            """\
+            name: myproject
+            version: 1.2.3
+            base: ubuntu@24.04
+            platforms:
+              amd64:
+              arm64:
+              riscv64:
+            parts:
+              mypart:
+                plugin: nil
+                source-tag: v$CRAFT_PROJECT_VERSION
+                build-environment:
+                - BUILD_ON: $CRAFT_ARCH_BUILD_ON
+                - BUILD_FOR: $CRAFT_ARCH_BUILD_FOR
             """
-        name: myproject
-        version: 1.2.3
-        base: ubuntu@24.04
-        platforms:
-          arm64:
-        parts:
-          mypart:
-            plugin: nil
-            source-tag: v$CRAFT_PROJECT_VERSION
-            build-environment:
-              - BUILD_ON: $CRAFT_ARCH_BUILD_ON
-              - BUILD_FOR: $CRAFT_ARCH_BUILD_FOR
-        """
         )
     )
-    monkeypatch.chdir(project_dir)
 
-    return project_path
+    return in_project_path
 
 
+@pytest.mark.usefixtures("in_project_path", "fake_host_architecture")
 def test_expand_environment_build_for_all(
-    monkeypatch, app_metadata, tmp_path, fake_services, emitter
+    monkeypatch, app_metadata, project_path, fake_services, emitter
 ):
     """Expand build-for to the host arch when build-for is 'all'."""
-    project_dir = tmp_path / "project"
-    project_dir.mkdir()
-    project_path = project_dir / "testcraft.yaml"
-    project_path.write_text(
+    project_file = project_path / "testcraft.yaml"
+    project_file.write_text(
         dedent(
             f"""\
             name: myproject
@@ -1388,7 +1386,6 @@ def test_expand_environment_build_for_all(
         """
         )
     )
-    monkeypatch.chdir(project_dir)
 
     app = application.Application(app_metadata, fake_services)
     project = app.get_project()
@@ -1406,7 +1403,7 @@ def test_expand_environment_build_for_all(
     )
 
 
-@pytest.mark.usefixtures("environment_project")
+@pytest.mark.usefixtures("environment_project", "fake_host_architecture")
 def test_application_expand_environment(app_metadata, fake_services):
     app = application.Application(app_metadata, fake_services)
     project = app.get_project(build_for=get_host_architecture())
@@ -1421,30 +1418,27 @@ def test_application_expand_environment(app_metadata, fake_services):
 
 
 @pytest.fixture
-def build_secrets_project(monkeypatch, tmp_path):
-    project_dir = tmp_path / "project"
-    project_dir.mkdir()
-    project_path = project_dir / "testcraft.yaml"
-    project_path.write_text(
+def build_secrets_project(in_project_path):
+    project_file = in_project_path / "testcraft.yaml"
+    project_file.write_text(
         dedent(
             """
-        name: myproject
-        version: 1.2.3
-        base: ubuntu@24.04
-        platforms:
-          arm64:
-        parts:
-          mypart:
-            plugin: nil
-            source: $(HOST_SECRET:echo ${SECRET_VAR_1})/project
-            build-environment:
-              - MY_VAR: $(HOST_SECRET:echo ${SECRET_VAR_2})
-        """
+            name: myproject
+            version: 1.2.3
+            base: ubuntu@24.04
+            platforms:
+              arm64:
+            parts:
+              mypart:
+                plugin: nil
+                source: $(HOST_SECRET:echo ${SECRET_VAR_1})/project
+                build-environment:
+                - MY_VAR: $(HOST_SECRET:echo ${SECRET_VAR_2})
+            """
         )
     )
-    monkeypatch.chdir(project_dir)
 
-    return project_path
+    return in_project_path
 
 
 @pytest.mark.usefixtures("build_secrets_project")
@@ -1652,14 +1646,13 @@ def grammar_project_full(tmp_path):
 
 
 @pytest.fixture
-def non_grammar_build_plan(mocker):
+def non_grammar_build_plan(mocker, fake_host_architecture):
     """A build plan to build on amd64 to riscv64."""
-    host_arch = "amd64"
     base = util.get_host_base()
     build_plan = [
         models.BuildInfo(
             "platform-riscv64",
-            host_arch,
+            fake_host_architecture,
             "riscv64",
             base,
         )
@@ -2150,9 +2143,9 @@ def test_build_planner_errors(tmp_path, monkeypatch, fake_services):
 def test_emitter_docs_url(monkeypatch, mocker, app):
     """Test that the emitter is initialized with the correct url."""
 
-    assert app.app.docs_url == "www.testcraft.example/docs/{version}"
+    assert app.app.docs_url == "http://testcraft.example/docs/{version}"
     assert app.app.version == "3.14159"
-    expected_url = "www.testcraft.example/docs/3.14159"
+    expected_url = "http://testcraft.example/docs/3.14159"
 
     spied_init = mocker.spy(emit, "init")
 
@@ -2243,7 +2236,7 @@ def test_doc_url_in_general_help(help_args, monkeypatch, capsys, app):
     with pytest.raises(SystemExit):
         app.run()
 
-    expected = "For more information about testcraft, check out: www.testcraft.example/docs/3.14159\n\n"
+    expected = "For more information about testcraft, check out: http://testcraft.example/docs/3.14159\n\n"
     _, err = capsys.readouterr()
     assert err.endswith(expected)
 
@@ -2257,6 +2250,6 @@ def test_doc_url_in_command_help(monkeypatch, capsys, app):
     with pytest.raises(SystemExit):
         app.run()
 
-    expected = "For more information, check out: www.testcraft.example/docs/3.14159/reference/commands/app-config\n\n"
+    expected = "For more information, check out: http://testcraft.example/docs/3.14159/reference/commands/app-config\n\n"
     _, err = capsys.readouterr()
     assert err.endswith(expected)
diff --git a/tests/unit/test_pytest_plugin.py b/tests/unit/test_pytest_plugin.py
new file mode 100644
index 00000000..071f0910
--- /dev/null
+++ b/tests/unit/test_pytest_plugin.py
@@ -0,0 +1,92 @@
+# Copyright 2025 Canonical Ltd.
+#
+# This program is free software: you can redistribute it and/or modify it
+# under the terms of the GNU Lesser General Public License version 3, as
+# published by the Free Software Foundation.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranties of MERCHANTABILITY,
+# SATISFACTORY QUALITY, or FITNESS FOR A PARTICULAR PURPOSE.
+# See the GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License along
+# with this program.  If not, see <http://www.gnu.org/licenses/>.
+"""Simple tests for the pytest plugin."""
+
+import os
+import pathlib
+import platform
+from unittest import mock
+
+import craft_platforms
+import pytest
+import pytest_check
+from pyfakefs.fake_filesystem import FakeFilesystem
+
+from craft_application import services, util
+
+
+def test_sets_debug_mode_auto_used(app_metadata):
+    assert os.getenv("CRAFT_DEBUG") == "1"
+
+    config_service = services.ConfigService(app=app_metadata, services=mock.Mock())
+    config_service.setup()
+    assert config_service.get("debug") is True
+
+
+@pytest.mark.usefixtures("production_mode")
+def test_production_mode_sets_production_mode(app_metadata):
+    assert os.getenv("CRAFT_DEBUG") == "0"
+
+    config_service = services.ConfigService(app=app_metadata, services=mock.Mock())
+    config_service.setup()
+    assert config_service.get("debug") is False
+
+
+@pytest.mark.usefixtures("managed_mode")
+def test_managed_mode():
+    assert services.ProviderService.is_managed() is True
+
+
+@pytest.mark.usefixtures("destructive_mode")
+def test_destructive_mode():
+    assert services.ProviderService.is_managed() is False
+    assert os.getenv("CRAFT_BUILD_ENVIRONMENT") == "host"
+
+
+@pytest.mark.xfail(
+    reason="Setup of this test should fail because the two fixtures cannot be used together.",
+    raises=LookupError,
+    strict=True,
+)
+@pytest.mark.usefixtures("managed_mode", "destructive_mode")
+def test_managed_and_destructive_mode_mutually_exclusive():
+    pass
+
+
+def test_host_architecture(fake_host_architecture: craft_platforms.DebianArchitecture):
+    platform_arch = fake_host_architecture.to_platform_arch()
+    pytest_check.equal(platform_arch, platform.uname().machine)
+    pytest_check.equal(platform_arch, platform.machine())
+    pytest_check.equal(fake_host_architecture.value, util.get_host_architecture())
+    pytest_check.equal(
+        fake_host_architecture, craft_platforms.DebianArchitecture.from_host()
+    )
+
+
+def test_project_path_created(project_path, tmp_path):
+    assert project_path.is_dir()
+    # Check that it's not the hardcoded fake path for pyfakefs.
+    assert project_path != pathlib.Path("/test/project")
+    assert project_path == tmp_path / "project"
+
+
+def test_project_path_created_with_pyfakefs(fs: FakeFilesystem, project_path):
+    assert fs.exists(project_path)
+    assert project_path.is_dir()
+    # Check that it's the hardcoded fake path for pyfakefs.
+    assert project_path == pathlib.Path("/test/project")
+
+
+def test_in_project_path(in_project_path):
+    assert pathlib.Path.cwd() == in_project_path