Remove assertion reinterpretation

The assertion reinterpretation is an old backwards compatibility
mode which was no longer being maintained on feature-parity with
the assertion rewriting mode.  It was also responsible for some
dubious patching of builtins and test with side-effects would
suddenly start passing.  Since re-writing has been the default for
a long time and plugins are now also re-written it is time to
retire reinterpretation.

Author: flub

CHANGELOG.rst

@@ -6,6 +6,10 @@
 A number of incompatible changes were made in this release, with the intent of removing features deprecated for a long
 time or change existing behaviors in order to make them less surprising/more useful.
 
+* Reinterpretation mode has now been removed.  Only plain and rewrite
+  mode are available, consequently the ``--assert=reinterp`` option is
+  no longer available.  Thanks `@flub`_ for the PR.
+
 * The following deprecated commandline options were removed:
 
   * ``--genscript``: no longer supported;

_pytest/_code/__init__.py

@@ -4,9 +4,6 @@
 from .code import Frame  # noqa
 from .code import Traceback  # noqa
 from .code import getrawcode  # noqa
-from .code import patch_builtins  # noqa
-from .code import unpatch_builtins  # noqa
 from .source import Source  # noqa
 from .source import compile_ as compile  # noqa
 from .source import getfslineno  # noqa
-

_pytest/_code/code.py

@@ -179,18 +179,6 @@ def getlocals(self):
         return self.frame.f_locals
     locals = property(getlocals, None, None, "locals of underlaying frame")
 
-    def reinterpret(self):
-        """Reinterpret the failing statement and returns a detailed information
-           about what operations are performed."""
-        from _pytest.assertion.reinterpret import reinterpret
-        if self.exprinfo is None:
-            source = py.builtin._totext(self.statement).strip()
-            x = reinterpret(source, self.frame, should_fail=True)
-            if not py.builtin._istext(x):
-                raise TypeError("interpret returned non-string %r" % (x,))
-            self.exprinfo = x
-        return self.exprinfo
-
     def getfirstlinesource(self):
         # on Jython this firstlineno can be -1 apparently
         return max(self.frame.code.firstlineno, 0)
@@ -830,29 +818,6 @@ def toterminal(self, tw):
             tw.line("")
 
 
-
-oldbuiltins = {}
-
-def patch_builtins(assertion=True, compile=True):
-    """ put compile and AssertionError builtins to Python's builtins. """
-    if assertion:
-        from _pytest.assertion import reinterpret
-        l = oldbuiltins.setdefault('AssertionError', [])
-        l.append(py.builtin.builtins.AssertionError)
-        py.builtin.builtins.AssertionError = reinterpret.AssertionError
-    if compile:
-        import _pytest._code
-        l = oldbuiltins.setdefault('compile', [])
-        l.append(py.builtin.builtins.compile)
-        py.builtin.builtins.compile = _pytest._code.compile
-
-def unpatch_builtins(assertion=True, compile=True):
-    """ remove compile and AssertionError builtins from Python builtins. """
-    if assertion:
-        py.builtin.builtins.AssertionError = oldbuiltins['AssertionError'].pop()
-    if compile:
-        py.builtin.builtins.compile = oldbuiltins['compile'].pop()
-
 def getrawcode(obj, trycall=True):
     """ return code object for given function. """
     try:

_pytest/assertion/__init__.py

@@ -14,16 +14,14 @@ def pytest_addoption(parser):
     group.addoption('--assert',
                     action="store",
                     dest="assertmode",
-                    choices=("rewrite", "reinterp", "plain",),
+                    choices=("rewrite", "plain",),
                     default="rewrite",
                     metavar="MODE",
-                    help="""control assertion debugging tools.  'plain'
-                            performs no assertion debugging.  'reinterp'
-                            reinterprets assert statements after they failed
-                            to provide assertion expression information.
-                            'rewrite' (the default) rewrites assert
-                            statements in test modules on import to
-                            provide assert expression information. """)
+                    help="""Control assertion debugging tools.  'plain'
+                            performs no assertion debugging.  'rewrite'
+                            (the default) rewrites assert statements in
+                            test modules on import to provide assert
+                            expression information.""")
 
 
 def pytest_namespace():
@@ -60,37 +58,21 @@ class AssertionState:
     def __init__(self, config, mode):
         self.mode = mode
         self.trace = config.trace.root.get("assertion")
+        self.hook = None
 
 
-def install_importhook(config, mode):
-    if mode == "rewrite":
-        try:
-            import ast  # noqa
-        except ImportError:
-            mode = "reinterp"
-        else:
-            # Both Jython and CPython 2.6.0 have AST bugs that make the
-            # assertion rewriting hook malfunction.
-            if (sys.platform.startswith('java') or
-                    sys.version_info[:3] == (2, 6, 0)):
-                mode = "reinterp"
-
-    config._assertstate = AssertionState(config, mode)
-
-    _load_modules(mode)
-    from _pytest.monkeypatch import MonkeyPatch
-    m = MonkeyPatch()
-    config._cleanup.append(m.undo)
-    m.setattr(py.builtin.builtins, 'AssertionError',
-              reinterpret.AssertionError)  # noqa
-
-    hook = None
-    if mode == "rewrite":
-        hook = rewrite.AssertionRewritingHook(config)  # noqa
-        sys.meta_path.insert(0, hook)
-
-    config._assertstate.hook = hook
-    config._assertstate.trace("configured with mode set to %r" % (mode,))
+def install_importhook(config):
+    """Try to install the rewrite hook, raise SystemError if it fails."""
+    # Both Jython and CPython 2.6.0 have AST bugs that make the
+    # assertion rewriting hook malfunction.
+    if (sys.platform.startswith('java') or
+            sys.version_info[:3] == (2, 6, 0)):
+        raise SystemError('rewrite not supported')
+
+    config._assertstate = AssertionState(config, 'rewrite')
+    config._assertstate.hook = hook = rewrite.AssertionRewritingHook(config)
+    sys.meta_path.insert(0, hook)
+    config._assertstate.trace('installed rewrite import hook')
     def undo():
         hook = config._assertstate.hook
         if hook is not None and hook in sys.meta_path:
@@ -169,13 +151,5 @@ def pytest_sessionfinish(session):
             assertstate.hook.set_session(None)
 
 
-def _load_modules(mode):
-    """Lazily import assertion related code."""
-    global rewrite, reinterpret
-    from _pytest.assertion import reinterpret  # noqa
-    if mode == "rewrite":
-        from _pytest.assertion import rewrite  # noqa
-
-
 # Expose this plugin's implementation for the pytest_assertrepr_compare hook
 pytest_assertrepr_compare = util.assertrepr_compare