From: whitequark <cz@m-labs.hk>
Date: Sun, 13 Oct 2019 18:53:38 +0000 (+0000)
Subject: {,_}tools→{,_}utils
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=bbf6324db4869391e5cf98800639728dbcd26934;p=nmigen.git

{,_}tools→{,_}utils

In context of nMigen, "tools" means "parts of toolchain", so it is
confusing to have a completely unrelated module also called "tools".
---

diff --git a/nmigen/_tools.py b/nmigen/_tools.py
deleted file mode 100644
index a62153d..0000000
--- a/nmigen/_tools.py
+++ /dev/null
@@ -1,84 +0,0 @@
-import contextlib
-import functools
-import warnings
-from collections import OrderedDict
-from collections.abc import Iterable
-from contextlib import contextmanager
-
-from .tools import *
-
-
-__all__ = ["flatten", "union" , "log2_int", "bits_for", "memoize", "final", "deprecated"]
-
-
-def flatten(i):
-    for e in i:
-        if isinstance(e, Iterable):
-            yield from flatten(e)
-        else:
-            yield e
-
-
-def union(i, start=None):
-    r = start
-    for e in i:
-        if r is None:
-            r = e
-        else:
-            r |= e
-    return r
-
-
-def memoize(f):
-    memo = OrderedDict()
-    @functools.wraps(f)
-    def g(*args):
-        if args not in memo:
-            memo[args] = f(*args)
-        return memo[args]
-    return g
-
-
-def final(cls):
-    def init_subclass():
-        raise TypeError("Subclassing {}.{} is not supported"
-                        .format(cls.__module__, cls.__name__))
-    cls.__init_subclass__ = init_subclass
-    return cls
-
-
-def deprecated(message, stacklevel=2):
-    def decorator(f):
-        @functools.wraps(f)
-        def wrapper(*args, **kwargs):
-            warnings.warn(message, DeprecationWarning, stacklevel=stacklevel)
-            return f(*args, **kwargs)
-        return wrapper
-    return decorator
-
-
-def _ignore_deprecated(f=None):
-    if f is None:
-        @contextlib.contextmanager
-        def context_like():
-            with warnings.catch_warnings():
-                warnings.filterwarnings(action="ignore", category=DeprecationWarning)
-                yield
-        return context_like()
-    else:
-        @functools.wraps(f)
-        def decorator_like(*args, **kwargs):
-            with warnings.catch_warnings():
-                warnings.filterwarnings(action="ignore", category=DeprecationWarning)
-                f(*args, **kwargs)
-        return decorator_like
-
-
-def extend(cls):
-    def decorator(f):
-        if isinstance(f, property):
-            name = f.fget.__name__
-        else:
-            name = f.__name__
-        setattr(cls, name, f)
-    return decorator
diff --git a/nmigen/_utils.py b/nmigen/_utils.py
new file mode 100644
index 0000000..85c8cdb
--- /dev/null
+++ b/nmigen/_utils.py
@@ -0,0 +1,84 @@
+import contextlib
+import functools
+import warnings
+from collections import OrderedDict
+from collections.abc import Iterable
+from contextlib import contextmanager
+
+from .utils import *
+
+
+__all__ = ["flatten", "union" , "log2_int", "bits_for", "memoize", "final", "deprecated"]
+
+
+def flatten(i):
+    for e in i:
+        if isinstance(e, Iterable):
+            yield from flatten(e)
+        else:
+            yield e
+
+
+def union(i, start=None):
+    r = start
+    for e in i:
+        if r is None:
+            r = e
+        else:
+            r |= e
+    return r
+
+
+def memoize(f):
+    memo = OrderedDict()
+    @functools.wraps(f)
+    def g(*args):
+        if args not in memo:
+            memo[args] = f(*args)
+        return memo[args]
+    return g
+
+
+def final(cls):
+    def init_subclass():
+        raise TypeError("Subclassing {}.{} is not supported"
+                        .format(cls.__module__, cls.__name__))
+    cls.__init_subclass__ = init_subclass
+    return cls
+
+
+def deprecated(message, stacklevel=2):
+    def decorator(f):
+        @functools.wraps(f)
+        def wrapper(*args, **kwargs):
+            warnings.warn(message, DeprecationWarning, stacklevel=stacklevel)
+            return f(*args, **kwargs)
+        return wrapper
+    return decorator
+
+
+def _ignore_deprecated(f=None):
+    if f is None:
+        @contextlib.contextmanager
+        def context_like():
+            with warnings.catch_warnings():
+                warnings.filterwarnings(action="ignore", category=DeprecationWarning)
+                yield
+        return context_like()
+    else:
+        @functools.wraps(f)
+        def decorator_like(*args, **kwargs):
+            with warnings.catch_warnings():
+                warnings.filterwarnings(action="ignore", category=DeprecationWarning)
+                f(*args, **kwargs)
+        return decorator_like
+
+
+def extend(cls):
+    def decorator(f):
+        if isinstance(f, property):
+            name = f.fget.__name__
+        else:
+            name = f.__name__
+        setattr(cls, name, f)
+    return decorator
diff --git a/nmigen/back/pysim.py b/nmigen/back/pysim.py
index 1ef8132..dc51e7c 100644
--- a/nmigen/back/pysim.py
+++ b/nmigen/back/pysim.py
@@ -6,7 +6,7 @@ from bitarray import bitarray
 from vcd import VCDWriter
 from vcd.gtkw import GTKWSave
 
-from .._tools import flatten
+from .._utils import flatten
 from ..hdl.ast import *
 from ..hdl.ir import *
 from ..hdl.xfrm import ValueVisitor, StatementVisitor
diff --git a/nmigen/back/rtlil.py b/nmigen/back/rtlil.py
index 2dfed0e..5a847c5 100644
--- a/nmigen/back/rtlil.py
+++ b/nmigen/back/rtlil.py
@@ -3,7 +3,7 @@ import textwrap
 from collections import defaultdict, OrderedDict
 from contextlib import contextmanager
 
-from .._tools import bits_for, flatten
+from .._utils import bits_for, flatten
 from ..hdl import ast, rec, ir, mem, xfrm
 
 
diff --git a/nmigen/compat/fhdl/bitcontainer.py b/nmigen/compat/fhdl/bitcontainer.py
index b52887d..648b129 100644
--- a/nmigen/compat/fhdl/bitcontainer.py
+++ b/nmigen/compat/fhdl/bitcontainer.py
@@ -1,19 +1,19 @@
-from ... import tools
+from ... import utils
 from ...hdl import ast
-from ..._tools import deprecated
+from ..._utils import deprecated
 
 
 __all__ = ["log2_int", "bits_for", "value_bits_sign"]
 
 
-@deprecated("instead of `log2_int`, use `nmigen.tools.log2_int`")
+@deprecated("instead of `log2_int`, use `nmigen.utils.log2_int`")
 def log2_int(n, need_pow2=True):
-    return tools.log2_int(n, need_pow2)
+    return utils.log2_int(n, need_pow2)
 
 
-@deprecated("instead of `bits_for`, use `nmigen.tools.bits_for`")
+@deprecated("instead of `bits_for`, use `nmigen.utils.bits_for`")
 def bits_for(n, require_sign_bit=False):
-    return tools.bits_for(n, require_sign_bit)
+    return utils.bits_for(n, require_sign_bit)
 
 
 @deprecated("instead of `value_bits_sign(v)`, use `v.shape()`")
diff --git a/nmigen/compat/fhdl/decorators.py b/nmigen/compat/fhdl/decorators.py
index 83f39b0..e61ccb5 100644
--- a/nmigen/compat/fhdl/decorators.py
+++ b/nmigen/compat/fhdl/decorators.py
@@ -2,7 +2,7 @@ from ...hdl.ast import *
 from ...hdl.xfrm import ResetInserter as NativeResetInserter
 from ...hdl.xfrm import EnableInserter as NativeEnableInserter
 from ...hdl.xfrm import DomainRenamer as NativeDomainRenamer
-from ..._tools import deprecated
+from ..._utils import deprecated
 
 
 __all__ = ["ResetInserter", "CEInserter", "ClockDomainsRenamer"]
diff --git a/nmigen/compat/fhdl/module.py b/nmigen/compat/fhdl/module.py
index 55dc96c..c403a5e 100644
--- a/nmigen/compat/fhdl/module.py
+++ b/nmigen/compat/fhdl/module.py
@@ -1,6 +1,6 @@
 from collections.abc import Iterable
 
-from ..._tools import flatten, deprecated
+from ..._utils import flatten, deprecated
 from ...hdl import dsl, ir
 
 
diff --git a/nmigen/compat/fhdl/specials.py b/nmigen/compat/fhdl/specials.py
index 2a49ffc..93111c2 100644
--- a/nmigen/compat/fhdl/specials.py
+++ b/nmigen/compat/fhdl/specials.py
@@ -1,6 +1,6 @@
 import warnings
 
-from ..._tools import deprecated, extend
+from ..._utils import deprecated, extend
 from ...hdl.ast import *
 from ...hdl.ir import Elaboratable
 from ...hdl.mem import Memory as NativeMemory
diff --git a/nmigen/compat/fhdl/structure.py b/nmigen/compat/fhdl/structure.py
index 91aea7f..27f639c 100644
--- a/nmigen/compat/fhdl/structure.py
+++ b/nmigen/compat/fhdl/structure.py
@@ -1,6 +1,6 @@
 from collections import OrderedDict
 
-from ..._tools import deprecated, extend
+from ..._utils import deprecated, extend
 from ...hdl import ast
 from ...hdl.ast import (DUID, Value, Signal, Mux, Slice as _Slice, Cat, Repl, Const, C,
                         ClockSignal, ResetSignal,
diff --git a/nmigen/compat/genlib/cdc.py b/nmigen/compat/genlib/cdc.py
index 7bfcd8c..3bdddb1 100644
--- a/nmigen/compat/genlib/cdc.py
+++ b/nmigen/compat/genlib/cdc.py
@@ -1,6 +1,6 @@
 import warnings
 
-from ..._tools import deprecated
+from ..._utils import deprecated
 from ...lib.cdc import FFSynchronizer as NativeFFSynchronizer
 from ...hdl.ast import *
 from ..fhdl.module import CompatModule
diff --git a/nmigen/compat/genlib/fifo.py b/nmigen/compat/genlib/fifo.py
index 0e4b55d..5c9bed7 100644
--- a/nmigen/compat/genlib/fifo.py
+++ b/nmigen/compat/genlib/fifo.py
@@ -1,4 +1,4 @@
-from ..._tools import deprecated, extend
+from ..._utils import deprecated, extend
 from ...lib.fifo import (FIFOInterface as NativeFIFOInterface,
   SyncFIFO as NativeSyncFIFO, SyncFIFOBuffered as NativeSyncFIFOBuffered,
   AsyncFIFO as NativeAsyncFIFO, AsyncFIFOBuffered as NativeAsyncFIFOBuffered)
diff --git a/nmigen/compat/genlib/fsm.py b/nmigen/compat/genlib/fsm.py
index 68b1d0a..fe8f525 100644
--- a/nmigen/compat/genlib/fsm.py
+++ b/nmigen/compat/genlib/fsm.py
@@ -1,6 +1,6 @@
 from collections import OrderedDict
 
-from ..._tools import deprecated, _ignore_deprecated
+from ..._utils import deprecated, _ignore_deprecated
 from ...hdl.xfrm import ValueTransformer, StatementTransformer
 from ...hdl.ast import *
 from ..fhdl.module import CompatModule, CompatFinalizeError
diff --git a/nmigen/compat/genlib/resetsync.py b/nmigen/compat/genlib/resetsync.py
index f7b5c4e..66f0bae 100644
--- a/nmigen/compat/genlib/resetsync.py
+++ b/nmigen/compat/genlib/resetsync.py
@@ -1,4 +1,4 @@
-from ..._tools import deprecated
+from ..._utils import deprecated
 from ...lib.cdc import ResetSynchronizer as NativeResetSynchronizer
 
 
diff --git a/nmigen/hdl/ast.py b/nmigen/hdl/ast.py
index 5d616c1..e0314cd 100644
--- a/nmigen/hdl/ast.py
+++ b/nmigen/hdl/ast.py
@@ -8,7 +8,7 @@ from collections.abc import Iterable, MutableMapping, MutableSet, MutableSequenc
 from enum import Enum
 
 from .. import tracer
-from .._tools import *
+from .._utils import *
 
 
 __all__ = [
diff --git a/nmigen/hdl/dsl.py b/nmigen/hdl/dsl.py
index b063482..598d812 100644
--- a/nmigen/hdl/dsl.py
+++ b/nmigen/hdl/dsl.py
@@ -4,7 +4,7 @@ from contextlib import contextmanager
 from enum import Enum
 import warnings
 
-from .._tools import flatten, bits_for, deprecated
+from .._utils import flatten, bits_for, deprecated
 from .. import tracer
 from .ast import *
 from .ir import *
diff --git a/nmigen/hdl/ir.py b/nmigen/hdl/ir.py
index 4232c52..44c3ecd 100644
--- a/nmigen/hdl/ir.py
+++ b/nmigen/hdl/ir.py
@@ -5,7 +5,7 @@ import warnings
 import traceback
 import sys
 
-from .._tools import *
+from .._utils import *
 from .ast import *
 from .cd import *
 
diff --git a/nmigen/hdl/rec.py b/nmigen/hdl/rec.py
index 7448ecd..d6c4686 100644
--- a/nmigen/hdl/rec.py
+++ b/nmigen/hdl/rec.py
@@ -3,7 +3,7 @@ from collections import OrderedDict
 from functools import reduce
 
 from .. import tracer
-from .._tools import union, deprecated
+from .._utils import union, deprecated
 from .ast import *
 
 
diff --git a/nmigen/hdl/xfrm.py b/nmigen/hdl/xfrm.py
index 2d4e639..8cd6936 100644
--- a/nmigen/hdl/xfrm.py
+++ b/nmigen/hdl/xfrm.py
@@ -2,7 +2,7 @@ from abc import ABCMeta, abstractmethod
 from collections import OrderedDict
 from collections.abc import Iterable
 
-from .._tools import flatten, deprecated
+from .._utils import flatten, deprecated
 from .. import tracer
 from .ast import *
 from .ast import _StatementList
diff --git a/nmigen/lib/cdc.py b/nmigen/lib/cdc.py
index 1294fb4..5dc865d 100644
--- a/nmigen/lib/cdc.py
+++ b/nmigen/lib/cdc.py
@@ -1,4 +1,4 @@
-from .._tools import deprecated
+from .._utils import deprecated
 from .. import *
 
 
diff --git a/nmigen/lib/fifo.py b/nmigen/lib/fifo.py
index 332d703..f3244df 100644
--- a/nmigen/lib/fifo.py
+++ b/nmigen/lib/fifo.py
@@ -2,7 +2,7 @@
 
 from .. import *
 from ..asserts import *
-from .._tools import log2_int, deprecated
+from .._utils import log2_int, deprecated
 from .coding import GrayEncoder
 from .cdc import FFSynchronizer
 
diff --git a/nmigen/test/compat/support.py b/nmigen/test/compat/support.py
index 22b97cc..8491652 100644
--- a/nmigen/test/compat/support.py
+++ b/nmigen/test/compat/support.py
@@ -1,4 +1,4 @@
-from ..._tools import _ignore_deprecated
+from ..._utils import _ignore_deprecated
 from ...compat import *
 from ...compat.fhdl import verilog
 
diff --git a/nmigen/test/compat/test_size.py b/nmigen/test/compat/test_size.py
index a739c2b..e3864f9 100644
--- a/nmigen/test/compat/test_size.py
+++ b/nmigen/test/compat/test_size.py
@@ -1,6 +1,6 @@
 import unittest
 
-from ..._tools import _ignore_deprecated
+from ..._utils import _ignore_deprecated
 from ...compat import *
 
 
diff --git a/nmigen/test/test_build_dsl.py b/nmigen/test/test_build_dsl.py
index 1e37d19..a613d12 100644
--- a/nmigen/test/test_build_dsl.py
+++ b/nmigen/test/test_build_dsl.py
@@ -1,7 +1,7 @@
 from collections import OrderedDict
 
 from ..build.dsl import *
-from .tools import *
+from .utils import *
 
 
 class PinsTestCase(FHDLTestCase):
diff --git a/nmigen/test/test_build_res.py b/nmigen/test/test_build_res.py
index fc111c8..40f4235 100644
--- a/nmigen/test/test_build_res.py
+++ b/nmigen/test/test_build_res.py
@@ -3,7 +3,7 @@ from ..hdl.rec import *
 from ..lib.io import *
 from ..build.dsl import *
 from ..build.res import *
-from .tools import *
+from .utils import *
 
 
 class ResourceManagerTestCase(FHDLTestCase):
diff --git a/nmigen/test/test_compat.py b/nmigen/test/test_compat.py
index d42812c..62e2d92 100644
--- a/nmigen/test/test_compat.py
+++ b/nmigen/test/test_compat.py
@@ -1,6 +1,6 @@
 from ..hdl.ir import Fragment
 from ..compat import *
-from .tools import *
+from .utils import *
 
 
 class CompatTestCase(FHDLTestCase):
diff --git a/nmigen/test/test_examples.py b/nmigen/test/test_examples.py
index e428a5e..94b9377 100644
--- a/nmigen/test/test_examples.py
+++ b/nmigen/test/test_examples.py
@@ -2,7 +2,7 @@ import sys
 import subprocess
 from pathlib import Path
 
-from .tools import *
+from .utils import *
 
 
 def example_test(name):
diff --git a/nmigen/test/test_hdl_ast.py b/nmigen/test/test_hdl_ast.py
index b7e9647..6968910 100644
--- a/nmigen/test/test_hdl_ast.py
+++ b/nmigen/test/test_hdl_ast.py
@@ -2,7 +2,7 @@ import warnings
 from enum import Enum
 
 from ..hdl.ast import *
-from .tools import *
+from .utils import *
 
 
 class UnsignedEnum(Enum):
diff --git a/nmigen/test/test_hdl_cd.py b/nmigen/test/test_hdl_cd.py
index 60edc3b..85bcfc8 100644
--- a/nmigen/test/test_hdl_cd.py
+++ b/nmigen/test/test_hdl_cd.py
@@ -1,5 +1,5 @@
 from ..hdl.cd import *
-from .tools import *
+from .utils import *
 
 
 class ClockDomainTestCase(FHDLTestCase):
diff --git a/nmigen/test/test_hdl_dsl.py b/nmigen/test/test_hdl_dsl.py
index 48993dd..85d205c 100644
--- a/nmigen/test/test_hdl_dsl.py
+++ b/nmigen/test/test_hdl_dsl.py
@@ -4,7 +4,7 @@ from enum import Enum
 from ..hdl.ast import *
 from ..hdl.cd import *
 from ..hdl.dsl import *
-from .tools import *
+from .utils import *
 
 
 class DSLTestCase(FHDLTestCase):
diff --git a/nmigen/test/test_hdl_ir.py b/nmigen/test/test_hdl_ir.py
index e51ae4e..6a85ebe 100644
--- a/nmigen/test/test_hdl_ir.py
+++ b/nmigen/test/test_hdl_ir.py
@@ -4,7 +4,7 @@ from ..hdl.ast import *
 from ..hdl.cd import *
 from ..hdl.ir import *
 from ..hdl.mem import *
-from .tools import *
+from .utils import *
 
 
 class BadElaboratable(Elaboratable):
diff --git a/nmigen/test/test_hdl_mem.py b/nmigen/test/test_hdl_mem.py
index 8cf3bb1..1a0a007 100644
--- a/nmigen/test/test_hdl_mem.py
+++ b/nmigen/test/test_hdl_mem.py
@@ -1,6 +1,6 @@
 from ..hdl.ast import *
 from ..hdl.mem import *
-from .tools import *
+from .utils import *
 
 
 class MemoryTestCase(FHDLTestCase):
diff --git a/nmigen/test/test_hdl_rec.py b/nmigen/test/test_hdl_rec.py
index 2e84107..dd9dd40 100644
--- a/nmigen/test/test_hdl_rec.py
+++ b/nmigen/test/test_hdl_rec.py
@@ -2,7 +2,7 @@ from enum import Enum
 
 from ..hdl.ast import *
 from ..hdl.rec import *
-from .tools import *
+from .utils import *
 
 
 class UnsignedEnum(Enum):
diff --git a/nmigen/test/test_hdl_xfrm.py b/nmigen/test/test_hdl_xfrm.py
index d67dc6f..c2e826a 100644
--- a/nmigen/test/test_hdl_xfrm.py
+++ b/nmigen/test/test_hdl_xfrm.py
@@ -3,7 +3,7 @@ from ..hdl.cd import *
 from ..hdl.ir import *
 from ..hdl.xfrm import *
 from ..hdl.mem import *
-from .tools import *
+from .utils import *
 
 
 class DomainRenamerTestCase(FHDLTestCase):
diff --git a/nmigen/test/test_lib_cdc.py b/nmigen/test/test_lib_cdc.py
index 23ebed5..1a394ea 100644
--- a/nmigen/test/test_lib_cdc.py
+++ b/nmigen/test/test_lib_cdc.py
@@ -1,4 +1,4 @@
-from .tools import *
+from .utils import *
 from ..hdl import *
 from ..back.pysim import *
 from ..lib.cdc import *
diff --git a/nmigen/test/test_lib_coding.py b/nmigen/test/test_lib_coding.py
index 6052c9a..874b87c 100644
--- a/nmigen/test/test_lib_coding.py
+++ b/nmigen/test/test_lib_coding.py
@@ -1,4 +1,4 @@
-from .tools import *
+from .utils import *
 from ..hdl import *
 from ..asserts import *
 from ..back.pysim import *
diff --git a/nmigen/test/test_lib_fifo.py b/nmigen/test/test_lib_fifo.py
index 2398f8f..26c5391 100644
--- a/nmigen/test/test_lib_fifo.py
+++ b/nmigen/test/test_lib_fifo.py
@@ -1,4 +1,4 @@
-from .tools import *
+from .utils import *
 from ..hdl import *
 from ..asserts import *
 from ..back.pysim import *
diff --git a/nmigen/test/test_lib_io.py b/nmigen/test/test_lib_io.py
index 7ae44a3..cb1cd46 100644
--- a/nmigen/test/test_lib_io.py
+++ b/nmigen/test/test_lib_io.py
@@ -1,4 +1,4 @@
-from .tools import *
+from .utils import *
 from ..hdl import *
 from ..hdl.rec import *
 from ..back.pysim import *
diff --git a/nmigen/test/test_sim.py b/nmigen/test/test_sim.py
index 91fec34..7ae6d97 100644
--- a/nmigen/test/test_sim.py
+++ b/nmigen/test/test_sim.py
@@ -1,7 +1,7 @@
 from contextlib import contextmanager
 
-from .tools import *
-from .._tools import flatten, union
+from .utils import *
+from .._utils import flatten, union
 from ..hdl.ast import *
 from ..hdl.cd import  *
 from ..hdl.mem import *
diff --git a/nmigen/test/tools.py b/nmigen/test/tools.py
deleted file mode 100644
index c3907ce..0000000
--- a/nmigen/test/tools.py
+++ /dev/null
@@ -1,103 +0,0 @@
-import os
-import re
-import shutil
-import subprocess
-import textwrap
-import traceback
-import unittest
-import warnings
-from contextlib import contextmanager
-
-from ..hdl.ast import *
-from ..hdl.ir import *
-from ..back import rtlil
-from .._toolchain import require_tool
-
-
-__all__ = ["FHDLTestCase"]
-
-
-class FHDLTestCase(unittest.TestCase):
-    def assertRepr(self, obj, repr_str):
-        if isinstance(obj, list):
-            obj = Statement.cast(obj)
-        def prepare_repr(repr_str):
-            repr_str = re.sub(r"\s+",   " ",  repr_str)
-            repr_str = re.sub(r"\( (?=\()", "(", repr_str)
-            repr_str = re.sub(r"\) (?=\))", ")", repr_str)
-            return repr_str.strip()
-        self.assertEqual(prepare_repr(repr(obj)), prepare_repr(repr_str))
-
-    @contextmanager
-    def assertRaises(self, exception, msg=None):
-        with super().assertRaises(exception) as cm:
-            yield
-        if msg is not None:
-            # WTF? unittest.assertRaises is completely broken.
-            self.assertEqual(str(cm.exception), msg)
-
-    @contextmanager
-    def assertRaisesRegex(self, exception, regex=None):
-        with super().assertRaises(exception) as cm:
-            yield
-        if regex is not None:
-            # unittest.assertRaisesRegex also seems broken...
-            self.assertRegex(str(cm.exception), regex)
-
-    @contextmanager
-    def assertWarns(self, category, msg=None):
-        with warnings.catch_warnings(record=True) as warns:
-            yield
-        self.assertEqual(len(warns), 1)
-        self.assertEqual(warns[0].category, category)
-        if msg is not None:
-            self.assertEqual(str(warns[0].message), msg)
-
-    def assertFormal(self, spec, mode="bmc", depth=1):
-        caller, *_ = traceback.extract_stack(limit=2)
-        spec_root, _ = os.path.splitext(caller.filename)
-        spec_dir = os.path.dirname(spec_root)
-        spec_name = "{}_{}".format(
-            os.path.basename(spec_root).replace("test_", "spec_"),
-            caller.name.replace("test_", "")
-        )
-
-        # The sby -f switch seems not fully functional when sby is reading from stdin.
-        if os.path.exists(os.path.join(spec_dir, spec_name)):
-            shutil.rmtree(os.path.join(spec_dir, spec_name))
-
-        if mode == "hybrid":
-            # A mix of BMC and k-induction, as per personal communication with Clifford Wolf.
-            script = "setattr -unset init w:* a:nmigen.sample_reg %d"
-            mode   = "bmc"
-        else:
-            script = ""
-
-        config = textwrap.dedent("""\
-        [options]
-        mode {mode}
-        depth {depth}
-        wait on
-
-        [engines]
-        smtbmc
-
-        [script]
-        read_ilang top.il
-        prep
-        {script}
-
-        [file top.il]
-        {rtlil}
-        """).format(
-            mode=mode,
-            depth=depth,
-            script=script,
-            rtlil=rtlil.convert(Fragment.get(spec, platform="formal"))
-        )
-        with subprocess.Popen([require_tool("sby"), "-f", "-d", spec_name], cwd=spec_dir,
-                              universal_newlines=True,
-                              stdin=subprocess.PIPE, stdout=subprocess.PIPE) as proc:
-            stdout, stderr = proc.communicate(config)
-            if proc.returncode != 0:
-                self.fail("Formal verification failed:\n" + stdout)
diff --git a/nmigen/test/utils.py b/nmigen/test/utils.py
new file mode 100644
index 0000000..c3907ce
--- /dev/null
+++ b/nmigen/test/utils.py
@@ -0,0 +1,103 @@
+import os
+import re
+import shutil
+import subprocess
+import textwrap
+import traceback
+import unittest
+import warnings
+from contextlib import contextmanager
+
+from ..hdl.ast import *
+from ..hdl.ir import *
+from ..back import rtlil
+from .._toolchain import require_tool
+
+
+__all__ = ["FHDLTestCase"]
+
+
+class FHDLTestCase(unittest.TestCase):
+    def assertRepr(self, obj, repr_str):
+        if isinstance(obj, list):
+            obj = Statement.cast(obj)
+        def prepare_repr(repr_str):
+            repr_str = re.sub(r"\s+",   " ",  repr_str)
+            repr_str = re.sub(r"\( (?=\()", "(", repr_str)
+            repr_str = re.sub(r"\) (?=\))", ")", repr_str)
+            return repr_str.strip()
+        self.assertEqual(prepare_repr(repr(obj)), prepare_repr(repr_str))
+
+    @contextmanager
+    def assertRaises(self, exception, msg=None):
+        with super().assertRaises(exception) as cm:
+            yield
+        if msg is not None:
+            # WTF? unittest.assertRaises is completely broken.
+            self.assertEqual(str(cm.exception), msg)
+
+    @contextmanager
+    def assertRaisesRegex(self, exception, regex=None):
+        with super().assertRaises(exception) as cm:
+            yield
+        if regex is not None:
+            # unittest.assertRaisesRegex also seems broken...
+            self.assertRegex(str(cm.exception), regex)
+
+    @contextmanager
+    def assertWarns(self, category, msg=None):
+        with warnings.catch_warnings(record=True) as warns:
+            yield
+        self.assertEqual(len(warns), 1)
+        self.assertEqual(warns[0].category, category)
+        if msg is not None:
+            self.assertEqual(str(warns[0].message), msg)
+
+    def assertFormal(self, spec, mode="bmc", depth=1):
+        caller, *_ = traceback.extract_stack(limit=2)
+        spec_root, _ = os.path.splitext(caller.filename)
+        spec_dir = os.path.dirname(spec_root)
+        spec_name = "{}_{}".format(
+            os.path.basename(spec_root).replace("test_", "spec_"),
+            caller.name.replace("test_", "")
+        )
+
+        # The sby -f switch seems not fully functional when sby is reading from stdin.
+        if os.path.exists(os.path.join(spec_dir, spec_name)):
+            shutil.rmtree(os.path.join(spec_dir, spec_name))
+
+        if mode == "hybrid":
+            # A mix of BMC and k-induction, as per personal communication with Clifford Wolf.
+            script = "setattr -unset init w:* a:nmigen.sample_reg %d"
+            mode   = "bmc"
+        else:
+            script = ""
+
+        config = textwrap.dedent("""\
+        [options]
+        mode {mode}
+        depth {depth}
+        wait on
+
+        [engines]
+        smtbmc
+
+        [script]
+        read_ilang top.il
+        prep
+        {script}
+
+        [file top.il]
+        {rtlil}
+        """).format(
+            mode=mode,
+            depth=depth,
+            script=script,
+            rtlil=rtlil.convert(Fragment.get(spec, platform="formal"))
+        )
+        with subprocess.Popen([require_tool("sby"), "-f", "-d", spec_name], cwd=spec_dir,
+                              universal_newlines=True,
+                              stdin=subprocess.PIPE, stdout=subprocess.PIPE) as proc:
+            stdout, stderr = proc.communicate(config)
+            if proc.returncode != 0:
+                self.fail("Formal verification failed:\n" + stdout)
diff --git a/nmigen/tools.py b/nmigen/tools.py
deleted file mode 100644
index 227258a..0000000
--- a/nmigen/tools.py
+++ /dev/null
@@ -1,21 +0,0 @@
-__all__ = ["log2_int", "bits_for"]
-
-
-def log2_int(n, need_pow2=True):
-    if n == 0:
-        return 0
-    r = (n - 1).bit_length()
-    if need_pow2 and (1 << r) != n:
-        raise ValueError("{} is not a power of 2".format(n))
-    return r
-
-
-def bits_for(n, require_sign_bit=False):
-    if n > 0:
-        r = log2_int(n + 1, False)
-    else:
-        require_sign_bit = True
-        r = log2_int(-n, False)
-    if require_sign_bit:
-        r += 1
-    return r
diff --git a/nmigen/utils.py b/nmigen/utils.py
new file mode 100644
index 0000000..227258a
--- /dev/null
+++ b/nmigen/utils.py
@@ -0,0 +1,21 @@
+__all__ = ["log2_int", "bits_for"]
+
+
+def log2_int(n, need_pow2=True):
+    if n == 0:
+        return 0
+    r = (n - 1).bit_length()
+    if need_pow2 and (1 << r) != n:
+        raise ValueError("{} is not a power of 2".format(n))
+    return r
+
+
+def bits_for(n, require_sign_bit=False):
+    if n > 0:
+        r = log2_int(n + 1, False)
+    else:
+        require_sign_bit = True
+        r = log2_int(-n, False)
+    if require_sign_bit:
+        r += 1
+    return r