Refactoring: Move exceptions module to be private

Hide all of buildstream's internal exceptions from the API surface.

50 files changed, 118 insertions, 109 deletions

diff --git a/buildstream/__init__.py b/buildstream/__init__.py
index 3d800610e..bb7a338a4 100644
--- a/buildstream/__init__.py
+++ b/buildstream/__init__.py
@@ -18,10 +18,6 @@
 #  Authors:
 #        Tristan Van Berkom <tristan.vanberkom@codethink.co.uk>
 
-# Exceptions and utilities first
-from .exceptions import PluginError, LoadError, LoadErrorReason, \
-    ImplError, ProgramNotFoundError, PlatformError, SandboxError
-
 # Core components
 from .context import Context
 from .project import Project
diff --git a/buildstream/_artifactcache/artifactcache.py b/buildstream/_artifactcache/artifactcache.py
index 246a7691d..66e6520c9 100644
--- a/buildstream/_artifactcache/artifactcache.py
+++ b/buildstream/_artifactcache/artifactcache.py
@@ -21,7 +21,8 @@
 import os
 from collections import Mapping
 
-from .. import utils, ImplError
+from .._exceptions import ImplError
+from .. import utils
 from .. import _yaml
 
 
diff --git a/buildstream/_artifactcache/ostreecache.py b/buildstream/_artifactcache/ostreecache.py
index 85ad3a4cf..d958c0bc5 100644
--- a/buildstream/_artifactcache/ostreecache.py
+++ b/buildstream/_artifactcache/ostreecache.py
@@ -24,7 +24,7 @@ import string
 import tempfile
 
 from .. import _ostree, utils
-from ..exceptions import _ArtifactError
+from .._exceptions import _ArtifactError
 from ..element import _KeyStrength
 from .._ostree import OSTreeError
 
diff --git a/buildstream/_artifactcache/tarcache.py b/buildstream/_artifactcache/tarcache.py
index 74ba0b3a0..5f28dcb41 100644
--- a/buildstream/_artifactcache/tarcache.py
+++ b/buildstream/_artifactcache/tarcache.py
@@ -26,7 +26,7 @@ import subprocess
 from .. import utils
 from ..element import _KeyStrength
 from .._message import Message, MessageType
-from ..exceptions import _ArtifactError, ProgramNotFoundError
+from .._exceptions import _ArtifactError, ProgramNotFoundError
 
 from . import ArtifactCache
 
diff --git a/buildstream/exceptions.py b/buildstream/_exceptions.py
index e896c0c20..c1deee786 100644
--- a/buildstream/exceptions.py
+++ b/buildstream/_exceptions.py
@@ -17,10 +17,6 @@
 #
 #  Authors:
 #        Tristan Van Berkom <tristan.vanberkom@codethink.co.uk>
-"""
-Exceptions
-==========
-"""
 
 from enum import Enum
 
@@ -60,98 +56,115 @@ class _BstError(Exception):
         _last_exception = self
 
 
+# PluginError
+#
+# Raised on plugin related errors.
+#
+# This exception is raised either by the plugin loading process,
+# or by the base :class:`.Plugin` element itself.
+#
 class PluginError(_BstError):
-    """Raised on plugin related errors.
-
-    This exception is raised either by the plugin loading process,
-    or by the base :class:`.Plugin` element itself.
-    """
     pass
 
 
+# LoadErrorReason
+#
+# Describes the reason why a :class:`.LoadError` was raised.
+#
 class LoadErrorReason(Enum):
-    """Describes the reason why a :class:`.LoadError` was raised.
-    """
 
+    # A file was not found.
     MISSING_FILE = 1
-    """A file was not found."""
 
+    # The parsed data was not valid YAML.
     INVALID_YAML = 2
-    """The parsed data was not valid YAML."""
 
+    # Data was malformed, a value was not of the expected type, etc
     INVALID_DATA = 3
-    """Data was malformed, a value was not of the expected type, etc"""
 
+    # An error occurred during YAML dictionary composition.
+    #
+    # This can happen by overriding a value with a new differently typed
+    # value, or by overwriting some named value when that was not allowed.
     ILLEGAL_COMPOSITE = 4
-    """An error occurred during YAML dictionary composition.
-
-    This can happen by overriding a value with a new differently typed
-    value, or by overwriting some named value when that was not allowed.
-    """
 
+    # An circular dependency chain was detected
     CIRCULAR_DEPENDENCY = 5
-    """An circular dependency chain was detected"""
 
+    # A variable could not be resolved. This can happen if your project
+    # has cyclic dependencies in variable declarations, or, when substituting
+    # a string which refers to an undefined variable.
     UNRESOLVED_VARIABLE = 6
-    """A variable could not be resolved. This can happen if your project
-    has cyclic dependencies in variable declarations, or, when substituting
-    a string which refers to an undefined variable.
-    """
 
+    # BuildStream does not support the required project format version
     UNSUPPORTED_PROJECT = 7
-    """BuildStream does not support the required project format version"""
 
+    # A conditional expression failed to resolve
     EXPRESSION_FAILED = 8
-    """A conditional expression failed to resolve"""
 
+    # An assertion was intentionally encoded into project YAML
     USER_ASSERTION = 9
-    """An assertion was intentionally encoded into project YAML"""
 
+    # A list composition directive did not apply to any underlying list
     TRAILING_LIST_DIRECTIVE = 10
-    """A list composition directive did not apply to any underlying list"""
 
 
+# LoadError
+#
+# Raised while loading some YAML.
+#
+# This exception is raised when loading or parsing YAML, or when
+# interpreting project YAML
+#
 class LoadError(_BstError):
-    """Raised while loading some YAML.
-
-    This exception is raised when loading or parsing YAML, or when
-    interpreting project YAML
-    """
     def __init__(self, reason, message):
         super(LoadError, self).__init__(message)
 
+        # The :class:`.LoadErrorReason` for which this exception was raised
+        #
         self.reason = reason
-        """The :class:`.LoadErrorReason` for which this exception was raised
-        """
 
 
+# ImplError
+#
+# Raised when a :class:`.Source` or :class:`.Element` plugin fails to
+# implement a mandatory method
+#
 class ImplError(_BstError):
-    """Raised when a :class:`.Source` or :class:`.Element` plugin fails to
-    implement a mandatory method"""
     pass
 
 
+# ProgramNotFoundError
+#
+# Raised if a required program is not found
+#
+# BuildStream requires various software to exist on the host for
+# it to work correctly. This exception is thrown if that software
+# can not be found. E.g. The :class:`.Sandbox` class expects that
+# bubblewrap is installed for it to work.
+#
 class ProgramNotFoundError(_BstError):
-    """Raised if a required program is not found
-
-    BuildSource requires various software to exist on the host for
-    it to work correctly. This exception is thrown if that software
-    can not be found. E.g. The :class:`.Sandbox` class expects that
-    bubblewrap is installed for it to work.
-    """
     pass
 
 
+# PlatformError
+#
+# Raised if the current platform is not supported.
 class PlatformError(_BstError):
-    """Raised if the current platform is not supported.
-    """
     pass
 
 
+# SandboxError
+#
+# Raised when errors are encountered by the sandbox implementation
+#
 class SandboxError(_BstError):
-    """Raised when errors are encountered by the sandbox implementation"""
     pass
 
 
+# ArtifactError
+#
+# Raised when errors are encountered in the artifact caches
+#
 class _ArtifactError(_BstError):
     pass
diff --git a/buildstream/_frontend/main.py b/buildstream/_frontend/main.py
index 12ed727ab..662f267cb 100644
--- a/buildstream/_frontend/main.py
+++ b/buildstream/_frontend/main.py
@@ -25,10 +25,10 @@ from contextlib import contextmanager
 from blessings import Terminal
 
 # Import buildstream public symbols
-from .. import Context, Project, Scope, Consistency, LoadError
+from .. import Context, Project, Scope, Consistency
 
 # Import various buildstream internals
-from ..exceptions import _BstError
+from .._exceptions import _BstError, LoadError
 from .._message import MessageType, unconditional_messages
 from .._pipeline import Pipeline, PipelineError
 from .._scheduler import Scheduler
diff --git a/buildstream/_frontend/widget.py b/buildstream/_frontend/widget.py
index e09f3d900..1d7a5ecc8 100644
--- a/buildstream/_frontend/widget.py
+++ b/buildstream/_frontend/widget.py
@@ -30,7 +30,7 @@ from mmap import mmap
 from .. import utils, _yaml
 from ..plugin import _plugin_lookup
 from .._message import MessageType
-from .. import ImplError
+from .._exceptions import ImplError
 from .. import Element, Scope, Consistency
 from . import Profile
 
diff --git a/buildstream/_loader.py b/buildstream/_loader.py
index 788a5c98e..9a3fd5eaa 100644
--- a/buildstream/_loader.py
+++ b/buildstream/_loader.py
@@ -23,7 +23,7 @@ import copy
 from functools import cmp_to_key
 from collections import Mapping, namedtuple
 
-from . import LoadError, LoadErrorReason
+from ._exceptions import LoadError, LoadErrorReason
 from . import _yaml
 from ._yaml import CompositeTypeError
 
diff --git a/buildstream/_options/optionbool.py b/buildstream/_options/optionbool.py
index a4619504d..db01340e4 100644
--- a/buildstream/_options/optionbool.py
+++ b/buildstream/_options/optionbool.py
@@ -19,7 +19,7 @@
 #        Tristan Van Berkom <tristan.vanberkom@codethink.co.uk>
 
 from .. import _yaml
-from .. import LoadError, LoadErrorReason
+from .._exceptions import LoadError, LoadErrorReason
 from .option import Option, OPTION_SYMBOLS
 
 
diff --git a/buildstream/_options/optionenum.py b/buildstream/_options/optionenum.py
index 5c4db7ddf..2ba8552d7 100644
--- a/buildstream/_options/optionenum.py
+++ b/buildstream/_options/optionenum.py
@@ -19,7 +19,7 @@
 #        Tristan Van Berkom <tristan.vanberkom@codethink.co.uk>
 
 from .. import _yaml
-from .. import LoadError, LoadErrorReason
+from .._exceptions import LoadError, LoadErrorReason
 from .option import Option, OPTION_SYMBOLS
 
 
diff --git a/buildstream/_options/optionflags.py b/buildstream/_options/optionflags.py
index 25d2d1c59..49ec70d85 100644
--- a/buildstream/_options/optionflags.py
+++ b/buildstream/_options/optionflags.py
@@ -19,7 +19,7 @@
 #        Tristan Van Berkom <tristan.vanberkom@codethink.co.uk>
 
 from .. import _yaml
-from .. import LoadError, LoadErrorReason
+from .._exceptions import LoadError, LoadErrorReason
 from .option import Option, OPTION_SYMBOLS
 
 
diff --git a/buildstream/_options/optionpool.py b/buildstream/_options/optionpool.py
index c2374c542..adca24a2d 100644
--- a/buildstream/_options/optionpool.py
+++ b/buildstream/_options/optionpool.py
@@ -23,7 +23,7 @@ import jinja2
 from collections import Mapping
 
 from .. import _yaml
-from .. import LoadError, LoadErrorReason
+from .._exceptions import LoadError, LoadErrorReason
 from .optionbool import OptionBool
 from .optionenum import OptionEnum
 from .optionflags import OptionFlags
diff --git a/buildstream/_ostree.py b/buildstream/_ostree.py
index a5029a690..8e390e94b 100644
--- a/buildstream/_ostree.py
+++ b/buildstream/_ostree.py
@@ -26,7 +26,7 @@ import os
 import subprocess
 from . import _site
 from . import utils
-from .exceptions import _BstError
+from ._exceptions import _BstError
 
 import gi
 gi.require_version('OSTree', '1.0')
diff --git a/buildstream/_pipeline.py b/buildstream/_pipeline.py
index edaf13318..1df57a9c1 100644
--- a/buildstream/_pipeline.py
+++ b/buildstream/_pipeline.py
@@ -29,12 +29,12 @@ from operator import itemgetter
 from tempfile import TemporaryDirectory
 from pluginbase import PluginBase
 
-from .exceptions import _BstError, _ArtifactError
+from ._exceptions import _BstError, _ArtifactError, ImplError, LoadError
 from ._message import Message, MessageType
 from ._elementfactory import ElementFactory
 from ._loader import Loader
 from ._sourcefactory import SourceFactory
-from . import Consistency, ImplError, LoadError
+from . import Consistency
 from . import Scope
 from . import _site
 from . import _yaml, utils
diff --git a/buildstream/_platform/linux.py b/buildstream/_platform/linux.py
index c94e3632d..cab9aa996 100644
--- a/buildstream/_platform/linux.py
+++ b/buildstream/_platform/linux.py
@@ -23,7 +23,7 @@ import sys
 import subprocess
 
 from .. import utils
-from .. import PlatformError
+from .._exceptions import PlatformError
 from .._message import Message, MessageType
 from ..sandbox import SandboxBwrap
 from .._artifactcache.ostreecache import OSTreeCache
diff --git a/buildstream/_platform/platform.py b/buildstream/_platform/platform.py
index 387abcb9a..0f3007cd9 100644
--- a/buildstream/_platform/platform.py
+++ b/buildstream/_platform/platform.py
@@ -23,7 +23,7 @@ import sys
 import platform
 
 from .. import utils
-from .. import PlatformError, ProgramNotFoundError, ImplError
+from .._exceptions import PlatformError, ProgramNotFoundError, ImplError
 
 
 class Platform():
diff --git a/buildstream/_platform/unix.py b/buildstream/_platform/unix.py
index 752386bdf..8a9f6ea17 100644
--- a/buildstream/_platform/unix.py
+++ b/buildstream/_platform/unix.py
@@ -23,7 +23,7 @@ import sys
 import pathlib
 
 from .. import utils
-from .. import PlatformError
+from .._exceptions import PlatformError
 from ..sandbox import SandboxChroot
 from .._artifactcache.tarcache import TarCache
 
diff --git a/buildstream/_plugincontext.py b/buildstream/_plugincontext.py
index 0207136ef..3b82954ed 100644
--- a/buildstream/_plugincontext.py
+++ b/buildstream/_plugincontext.py
@@ -22,7 +22,7 @@ import os
 import inspect
 import pkg_resources
 
-from .exceptions import PluginError
+from ._exceptions import PluginError
 from . import utils
 
 
diff --git a/buildstream/_scheduler/job.py b/buildstream/_scheduler/job.py
index 90551b712..d8e720d9f 100644
--- a/buildstream/_scheduler/job.py
+++ b/buildstream/_scheduler/job.py
@@ -30,7 +30,7 @@ import multiprocessing
 from ruamel import yaml
 
 # BuildStream toplevel imports
-from ..exceptions import _BstError
+from .._exceptions import _BstError
 from .._message import Message, MessageType, unconditional_messages
 from ..plugin import _plugin_lookup
 from .. import _yaml, _signals, utils
diff --git a/buildstream/_variables.py b/buildstream/_variables.py
index dfbd8ff04..15e5ecac1 100644
--- a/buildstream/_variables.py
+++ b/buildstream/_variables.py
@@ -20,7 +20,7 @@
 
 import re
 
-from . import LoadError, LoadErrorReason
+from ._exceptions import LoadError, LoadErrorReason
 from . import _yaml
 
 # Variables are allowed to have dashes here
diff --git a/buildstream/_yaml.py b/buildstream/_yaml.py
index 8aa2ec714..153e744f4 100644
--- a/buildstream/_yaml.py
+++ b/buildstream/_yaml.py
@@ -26,7 +26,7 @@ from contextlib import ExitStack
 
 from ruamel import yaml
 from ruamel.yaml.representer import SafeRepresenter, RoundTripRepresenter
-from . import ImplError, LoadError, LoadErrorReason
+from ._exceptions import LoadError, LoadErrorReason
 
 
 # We store information in the loaded yaml on a DictProvenance
@@ -57,7 +57,7 @@ class Provenance():
 
     # Abstract method
     def clone(self):
-        raise ImplError("Unimplemented clone() in Provenance")
+        pass  # pragma: nocover
 
 
 # A Provenance for dictionaries, these are stored in the copy of the
diff --git a/buildstream/context.py b/buildstream/context.py
index a644da281..81929591a 100644
--- a/buildstream/context.py
+++ b/buildstream/context.py
@@ -39,7 +39,7 @@ from collections import deque, Mapping
 from . import _site
 from . import _yaml
 from . import utils
-from . import LoadError, LoadErrorReason
+from ._exceptions import LoadError, LoadErrorReason
 from ._profile import Topics, profile_start, profile_end
 
 
diff --git a/buildstream/element.py b/buildstream/element.py
index 0c121cd1c..054c75667 100644
--- a/buildstream/element.py
+++ b/buildstream/element.py
@@ -37,8 +37,7 @@ import shutil
 
 from . import _yaml
 from ._variables import Variables
-from .exceptions import _BstError, _ArtifactError
-from . import LoadError, LoadErrorReason, ImplError
+from ._exceptions import _BstError, _ArtifactError, LoadError, LoadErrorReason, ImplError
 from . import Plugin, Consistency
 from .project import BST_ARTIFACT_VERSION as BST_CORE_ARTIFACT_VERSION
 from . import SandboxFlags
diff --git a/buildstream/plugin.py b/buildstream/plugin.py
index 93bac3465..23d34ab10 100644
--- a/buildstream/plugin.py
+++ b/buildstream/plugin.py
@@ -77,8 +77,7 @@ from weakref import WeakValueDictionary
 
 from . import _yaml, _signals
 from . import utils
-from . import PluginError, ImplError
-from .exceptions import _BstError
+from ._exceptions import PluginError, ImplError, _BstError
 from ._message import Message, MessageType
 
 
diff --git a/buildstream/project.py b/buildstream/project.py
index 66561041e..d83159711 100644
--- a/buildstream/project.py
+++ b/buildstream/project.py
@@ -34,7 +34,7 @@ from . import utils
 from . import _site
 from . import _yaml
 from ._profile import Topics, profile_start, profile_end
-from . import LoadError, LoadErrorReason
+from ._exceptions import LoadError, LoadErrorReason
 from ._options import OptionPool
 
 BST_FORMAT_VERSION = 0
diff --git a/buildstream/sandbox/_mount.py b/buildstream/sandbox/_mount.py
index 472534c9e..f78d3aa3d 100644
--- a/buildstream/sandbox/_mount.py
+++ b/buildstream/sandbox/_mount.py
@@ -1,7 +1,7 @@
 import sys
 from contextlib import contextmanager
 
-from .. import SandboxError
+from .._exceptions import SandboxError
 from .. import utils, _signals
 
 
diff --git a/buildstream/sandbox/_sandboxchroot.py b/buildstream/sandbox/_sandboxchroot.py
index b1c5997fa..33f991b87 100644
--- a/buildstream/sandbox/_sandboxchroot.py
+++ b/buildstream/sandbox/_sandboxchroot.py
@@ -27,7 +27,7 @@ import signal
 import subprocess
 from contextlib import contextmanager, ExitStack
 
-from .. import SandboxError
+from .._exceptions import SandboxError
 from .. import utils
 from .. import _signals
 from ._mount import Mount
diff --git a/buildstream/sandbox/sandbox.py b/buildstream/sandbox/sandbox.py
index 1df094c39..0dc9aa2a5 100644
--- a/buildstream/sandbox/sandbox.py
+++ b/buildstream/sandbox/sandbox.py
@@ -33,7 +33,7 @@ from collections import OrderedDict
 from contextlib import contextmanager, ExitStack
 
 from .. import utils
-from .. import ImplError
+from .._exceptions import ImplError
 from .._fuse import SafeHardlinks
 
 
diff --git a/buildstream/source.py b/buildstream/source.py
index bab759989..aeae41220 100644
--- a/buildstream/source.py
+++ b/buildstream/source.py
@@ -28,8 +28,7 @@ import shutil
 from contextlib import contextmanager
 
 from . import _yaml, _signals, utils
-from .exceptions import _BstError
-from . import ImplError, LoadError, LoadErrorReason
+from ._exceptions import _BstError, ImplError, LoadError, LoadErrorReason
 from . import Plugin
 
 
diff --git a/buildstream/utils.py b/buildstream/utils.py
index 7caf107a4..637d583b0 100644
--- a/buildstream/utils.py
+++ b/buildstream/utils.py
@@ -38,7 +38,7 @@ import re
 import tempfile
 import pkg_resources
 from contextlib import contextmanager
-from . import ProgramNotFoundError
+from ._exceptions import ProgramNotFoundError
 from . import _yaml
 from . import _signals
 
diff --git a/tests/artifactcache/tar.py b/tests/artifactcache/tar.py
index 835c5034d..d982aab01 100644
--- a/tests/artifactcache/tar.py
+++ b/tests/artifactcache/tar.py
@@ -7,7 +7,7 @@ import pytest
 
 from buildstream._artifactcache.tarcache import Tar
 from buildstream.utils import get_host_tool
-from buildstream.exceptions import ProgramNotFoundError
+from buildstream._exceptions import ProgramNotFoundError
 
 
 # Test that it 'works' - this may be equivalent to test_archive_no_tar()
diff --git a/tests/context/context.py b/tests/context/context.py
index 48ce037f7..be0dd8a55 100644
--- a/tests/context/context.py
+++ b/tests/context/context.py
@@ -2,7 +2,7 @@ import os
 import pytest
 
 from buildstream import Context
-from buildstream import LoadError, LoadErrorReason
+from buildstream._exceptions import LoadError, LoadErrorReason
 
 from tests.testutils.site import HAVE_ROOT
 
diff --git a/tests/format/assertion.py b/tests/format/assertion.py
index ec1305081..27a3d3fc7 100644
--- a/tests/format/assertion.py
+++ b/tests/format/assertion.py
@@ -1,7 +1,7 @@
 import os
 import pytest
 from buildstream import _yaml
-from buildstream import LoadError, LoadErrorReason
+from buildstream._exceptions import LoadError, LoadErrorReason
 from tests.testutils.runcli import cli
 
 # Project directory
diff --git a/tests/format/listdirectiveerrors.py b/tests/format/listdirectiveerrors.py
index 9f2cfaaca..8a5d4f152 100644
--- a/tests/format/listdirectiveerrors.py
+++ b/tests/format/listdirectiveerrors.py
@@ -1,7 +1,7 @@
 import os
 import pytest
 from buildstream import _yaml
-from buildstream import LoadError, LoadErrorReason
+from buildstream._exceptions import LoadError, LoadErrorReason
 from tests.testutils.runcli import cli
 
 # Project directory
diff --git a/tests/format/optionarch.py b/tests/format/optionarch.py
index fce689800..5d28b83f2 100644
--- a/tests/format/optionarch.py
+++ b/tests/format/optionarch.py
@@ -2,7 +2,7 @@ import os
 import pytest
 from contextlib import contextmanager
 from buildstream import _yaml
-from buildstream import LoadError, LoadErrorReason
+from buildstream._exceptions import LoadError, LoadErrorReason
 from tests.testutils.runcli import cli
 
 # Project directory
diff --git a/tests/format/optionbool.py b/tests/format/optionbool.py
index a02ec742e..3c33a8713 100644
--- a/tests/format/optionbool.py
+++ b/tests/format/optionbool.py
@@ -1,7 +1,7 @@
 import os
 import pytest
 from buildstream import _yaml
-from buildstream import LoadError, LoadErrorReason
+from buildstream._exceptions import LoadError, LoadErrorReason
 from tests.testutils.runcli import cli
 
 # Project directory
diff --git a/tests/format/optioneltmask.py b/tests/format/optioneltmask.py
index 83ccf8b6f..84c594772 100644
--- a/tests/format/optioneltmask.py
+++ b/tests/format/optioneltmask.py
@@ -1,7 +1,7 @@
 import os
 import pytest
 from buildstream import _yaml
-from buildstream import LoadError, LoadErrorReason
+from buildstream._exceptions import LoadError, LoadErrorReason
 from tests.testutils.runcli import cli
 
 # Project directory
diff --git a/tests/format/optionenum.py b/tests/format/optionenum.py
index 5804a5fc1..19dd3d4af 100644
--- a/tests/format/optionenum.py
+++ b/tests/format/optionenum.py
@@ -1,7 +1,7 @@
 import os
 import pytest
 from buildstream import _yaml
-from buildstream import LoadError, LoadErrorReason
+from buildstream._exceptions import LoadError, LoadErrorReason
 from tests.testutils.runcli import cli
 
 # Project directory
diff --git a/tests/format/optionexports.py b/tests/format/optionexports.py
index 849c9148e..d824f0306 100644
--- a/tests/format/optionexports.py
+++ b/tests/format/optionexports.py
@@ -1,7 +1,7 @@
 import os
 import pytest
 from buildstream import _yaml
-from buildstream import LoadError, LoadErrorReason
+from buildstream._exceptions import LoadError, LoadErrorReason
 from tests.testutils.runcli import cli
 
 # Project directory
diff --git a/tests/format/optionflags.py b/tests/format/optionflags.py
index 7ad5f2485..de48ab9d1 100644
--- a/tests/format/optionflags.py
+++ b/tests/format/optionflags.py
@@ -1,7 +1,7 @@
 import os
 import pytest
 from buildstream import _yaml
-from buildstream import LoadError, LoadErrorReason
+from buildstream._exceptions import LoadError, LoadErrorReason
 from tests.testutils.runcli import cli
 
 # Project directory
diff --git a/tests/format/options.py b/tests/format/options.py
index 5cb01622c..1cfea7c71 100644
--- a/tests/format/options.py
+++ b/tests/format/options.py
@@ -1,7 +1,7 @@
 import os
 import pytest
 from buildstream import _yaml
-from buildstream import LoadError, LoadErrorReason
+from buildstream._exceptions import LoadError, LoadErrorReason
 from tests.testutils.runcli import cli
 
 # Project directory
diff --git a/tests/format/projectoverrides.py b/tests/format/projectoverrides.py
index 4d6eb14f5..1824ff0be 100644
--- a/tests/format/projectoverrides.py
+++ b/tests/format/projectoverrides.py
@@ -2,7 +2,7 @@
 import os
 import pytest
 from buildstream import _yaml
-from buildstream import LoadError, LoadErrorReason
+from buildstream._exceptions import LoadError, LoadErrorReason
 from tests.testutils.runcli import cli
 
 # Project directory
diff --git a/tests/loader/basics.py b/tests/loader/basics.py
index 3135b4b6e..db92efb36 100644
--- a/tests/loader/basics.py
+++ b/tests/loader/basics.py
@@ -1,7 +1,7 @@
 import os
 import pytest
 
-from buildstream import LoadError, LoadErrorReason
+from buildstream._exceptions import LoadError, LoadErrorReason
 from buildstream._loader import Loader
 from buildstream._metaelement import MetaElement
 from . import make_options
diff --git a/tests/loader/dependencies.py b/tests/loader/dependencies.py
index ac6ee5d4b..bd588867b 100644
--- a/tests/loader/dependencies.py
+++ b/tests/loader/dependencies.py
@@ -1,7 +1,7 @@
 import os
 import pytest
 
-from buildstream import LoadError, LoadErrorReason
+from buildstream._exceptions import LoadError, LoadErrorReason
 from buildstream._loader import Loader
 from buildstream._metaelement import MetaElement
 from . import make_options
diff --git a/tests/plugins/basics.py b/tests/plugins/basics.py
index db72a29bc..993d87cec 100644
--- a/tests/plugins/basics.py
+++ b/tests/plugins/basics.py
@@ -4,7 +4,7 @@ import pytest
 from pluginbase import PluginBase
 from buildstream._elementfactory import ElementFactory
 from buildstream._sourcefactory import SourceFactory
-from buildstream import PluginError
+from buildstream._exceptions import PluginError
 
 DATA_DIR = os.path.join(
     os.path.dirname(os.path.realpath(__file__)),
diff --git a/tests/plugins/pipeline.py b/tests/plugins/pipeline.py
index 1d4133f9e..f5c9a0c8f 100644
--- a/tests/plugins/pipeline.py
+++ b/tests/plugins/pipeline.py
@@ -1,7 +1,8 @@
 import os
 import pytest
 
-from buildstream import Context, Project, Scope, PluginError
+from buildstream import Context, Project, Scope
+from buildstream._exceptions import PluginError
 from buildstream._pipeline import Pipeline
 from buildstream._platform import Platform
 
diff --git a/tests/project/project.py b/tests/project/project.py
index 15baa7d3c..430e15b11 100644
--- a/tests/project/project.py
+++ b/tests/project/project.py
@@ -2,7 +2,7 @@ import os
 import pytest
 
 from buildstream import Project, Context
-from buildstream import LoadError, LoadErrorReason
+from buildstream._exceptions import LoadError, LoadErrorReason
 
 DATA_DIR = os.path.join(
     os.path.dirname(os.path.realpath(__file__)),
diff --git a/tests/testutils/runcli.py b/tests/testutils/runcli.py
index 593bc9448..0336d8fd5 100644
--- a/tests/testutils/runcli.py
+++ b/tests/testutils/runcli.py
@@ -10,7 +10,7 @@ from buildstream._frontend.main import cli as bst_cli
 from buildstream import _yaml
 
 # Special private exception accessor, for test case purposes
-from buildstream.exceptions import _get_last_exception
+from buildstream._exceptions import _get_last_exception
 
 
 # Wrapper for the click.testing result
diff --git a/tests/testutils/site.py b/tests/testutils/site.py
index 86a300da0..79538efbf 100644
--- a/tests/testutils/site.py
+++ b/tests/testutils/site.py
@@ -4,24 +4,25 @@
 import os
 import sys
 
-from buildstream import exceptions, utils
+from buildstream import utils
+from buildstream._exceptions import ProgramNotFoundError
 
 try:
     utils.get_host_tool('bzr')
     HAVE_BZR = True
-except exceptions.ProgramNotFoundError:
+except ProgramNotFoundError:
     HAVE_BZR = False
 
 try:
     utils.get_host_tool('git')
     HAVE_GIT = True
-except exceptions.ProgramNotFoundError:
+except ProgramNotFoundError:
     HAVE_GIT = False
 
 try:
     utils.get_host_tool('ostree')
     HAVE_OSTREE_CLI = True
-except exceptions.ProgramNotFoundError:
+except ProgramNotFoundError:
     HAVE_OSTREE_CLI = False
 
 try:
@@ -33,7 +34,7 @@ except (ImportError, ValueError):
 try:
     utils.get_host_tool('bwrap')
     HAVE_BWRAP = True
-except exceptions.ProgramNotFoundError:
+except ProgramNotFoundError:
     HAVE_BWRAP = False
 
 IS_LINUX = os.getenv('BST_FORCE_BACKEND', sys.platform).startswith('linux')
diff --git a/tests/yaml/yaml.py b/tests/yaml/yaml.py
index cf12317a9..0aae28f08 100644
--- a/tests/yaml/yaml.py
+++ b/tests/yaml/yaml.py
@@ -3,7 +3,7 @@ import pytest
 from collections import Mapping
 
 from buildstream import _yaml
-from buildstream import LoadError, LoadErrorReason
+from buildstream._exceptions import LoadError, LoadErrorReason
 
 DATA_DIR = os.path.join(
     os.path.dirname(os.path.realpath(__file__)),