Merge remote-tracking branch 'upstream/master' into release-3.8.0

src/_pytest/assertion/rewrite.py

@@ -67,14 +67,24 @@ class AssertionRewritingHook(object):
         # flag to guard against trying to rewrite a pyc file while we are already writing another pyc file,
         # which might result in infinite recursion (#3506)
         self._writing_pyc = False
+        self._basenames_to_check_rewrite = {"conftest"}
+        self._marked_for_rewrite_cache = {}
+        self._session_paths_checked = False
 
     def set_session(self, session):
         self.session = session
+        self._session_paths_checked = False
+
+    def _imp_find_module(self, name, path=None):
+        """Indirection so we can mock calls to find_module originated from the hook during testing"""
+        return imp.find_module(name, path)
 
     def find_module(self, name, path=None):
         if self._writing_pyc:
             return None
         state = self.config._assertstate
+        if self._early_rewrite_bailout(name, state):
+            return None
         state.trace("find_module called for: %s" % name)
         names = name.rsplit(".", 1)
         lastname = names[-1]
@@ -87,7 +97,7 @@ class AssertionRewritingHook(object):
                 pth = path[0]
         if pth is None:
             try:
-                fd, fn, desc = imp.find_module(lastname, path)
+                fd, fn, desc = self._imp_find_module(lastname, path)
             except ImportError:
                 return None
             if fd is not None:
@@ -166,6 +176,44 @@ class AssertionRewritingHook(object):
         self.modules[name] = co, pyc
         return self
 
+    def _early_rewrite_bailout(self, name, state):
+        """
+        This is a fast way to get out of rewriting modules. Profiling has
+        shown that the call to imp.find_module (inside of the find_module
+        from this class) is a major slowdown, so, this method tries to
+        filter what we're sure won't be rewritten before getting to it.
+        """
+        if self.session is not None and not self._session_paths_checked:
+            self._session_paths_checked = True
+            for path in self.session._initialpaths:
+                # Make something as c:/projects/my_project/path.py ->
+                #     ['c:', 'projects', 'my_project', 'path.py']
+                parts = str(path).split(os.path.sep)
+                # add 'path' to basenames to be checked.
+                self._basenames_to_check_rewrite.add(os.path.splitext(parts[-1])[0])
+
+        # Note: conftest already by default in _basenames_to_check_rewrite.
+        parts = name.split(".")
+        if parts[-1] in self._basenames_to_check_rewrite:
+            return False
+
+        # For matching the name it must be as if it was a filename.
+        parts[-1] = parts[-1] + ".py"
+        fn_pypath = py.path.local(os.path.sep.join(parts))
+        for pat in self.fnpats:
+            # if the pattern contains subdirectories ("tests/**.py" for example) we can't bail out based
+            # on the name alone because we need to match against the full path
+            if os.path.dirname(pat):
+                return False
+            if fn_pypath.fnmatch(pat):
+                return False
+
+        if self._is_marked_for_rewrite(name, state):
+            return False
+
+        state.trace("early skip of rewriting module: %s" % (name,))
+        return True
+
     def _should_rewrite(self, name, fn_pypath, state):
         # always rewrite conftest files
         fn = str(fn_pypath)
@@ -185,12 +233,20 @@ class AssertionRewritingHook(object):
                 state.trace("matched test file %r" % (fn,))
                 return True
 
-        for marked in self._must_rewrite:
-            if name == marked or name.startswith(marked + "."):
-                state.trace("matched marked file %r (from %r)" % (name, marked))
-                return True
+        return self._is_marked_for_rewrite(name, state)
 
-        return False
+    def _is_marked_for_rewrite(self, name, state):
+        try:
+            return self._marked_for_rewrite_cache[name]
+        except KeyError:
+            for marked in self._must_rewrite:
+                if name == marked or name.startswith(marked + "."):
+                    state.trace("matched marked file %r (from %r)" % (name, marked))
+                    self._marked_for_rewrite_cache[name] = True
+                    return True
+
+            self._marked_for_rewrite_cache[name] = False
+            return False
 
     def mark_rewrite(self, *names):
         """Mark import names as needing to be rewritten.
@@ -207,6 +263,7 @@ class AssertionRewritingHook(object):
             ):
                 self._warn_already_imported(name)
         self._must_rewrite.update(names)
+        self._marked_for_rewrite_cache.clear()
 
     def _warn_already_imported(self, name):
         from _pytest.warning_types import PytestWarning
@@ -245,7 +302,7 @@ class AssertionRewritingHook(object):
 
     def is_package(self, name):
         try:
-            fd, fn, desc = imp.find_module(name)
+            fd, fn, desc = self._imp_find_module(name)
         except ImportError:
             return False
         if fd is not None: