introduce a new pytest_ignore_collect_path(path, config) hook -

returning a true value will prevent considering the path for collection
The hook is called for both files and directory paths.

--HG--
branch : trunk

CHANGELOG

@@ -8,6 +8,12 @@ Changes between 1.2.1 and 1.2.2 (release pending)
 - fixes for handling of unicode exception values and unprintable objects
 - (issue87) fix unboundlocal error in assertionold code 
 - (issue86) improve documentation for looponfailing
+- add a new pytest_ignore_collect_path(path, config) hook to allow projects and
+  plugins to define exclusion behaviour for their directory structure - 
+  for example you may define in a conftest.py this method:
+        def pytest_ignore_collect_path(path):
+            return path.check(link=1)
+  to prevent even a collection try of any tests in symlinked dirs. 
 - expose previously internal commonly useful methods: 
   py.io.get_terminal_with() -> return terminal width
   py.io.ansi_print(...) -> print colored/bold text on linux/win32

py/_plugin/hookspec.py

@@ -27,6 +27,13 @@ def pytest_unconfigure(config):
 # collection hooks
 # -------------------------------------------------------------------------
 
+def pytest_ignore_collect_path(path, config):
+    """ return true value to prevent considering this path for collection. 
+    This hook is consulted for all files and directories prior to considering
+    collection hooks. 
+    """
+pytest_ignore_collect_path.firstresult = True
+
 def pytest_collect_directory(path, parent):
     """ return Collection node or None for the given path. """
 pytest_collect_directory.firstresult = True

py/_plugin/pytest_default.py

@@ -24,6 +24,20 @@ def pytest_funcarg__pytestconfig(request):
     """ the pytest config object with access to command line opts."""
     return request.config
 
+def pytest_ignore_collect_path(path, config):
+    ignore_paths = config.getconftest_pathlist("collect_ignore", path=path) 
+    ignore_paths = ignore_paths or []
+    excludeopt = config.getvalue("ignore")
+    if excludeopt:
+        ignore_paths.extend([py.path.local(x) for x in excludeopt])
+    return path in ignore_paths
+    # XXX more refined would be: 
+    if ignore_paths:
+        for p in ignore_paths:
+            if path == p or path.relto(p):
+                return True
+
+
 def pytest_collect_directory(path, parent):
     # XXX reconsider the following comment 
     # not use parent.Directory here as we generally 

py/_test/collect.py

@@ -296,21 +296,8 @@ class Directory(FSCollector):
                     l.append(res)
         return l
 
-    def _ignore(self, path):
-        ignore_paths = self.config.getconftest_pathlist("collect_ignore", 
-            path=path) or []
-        excludeopt = self.config.getvalue("ignore")
-        if excludeopt:
-            ignore_paths.extend([py.path.local(x) for x in excludeopt])
-        return path in ignore_paths
-        # XXX more refined would be: 
-        if ignore_paths:
-            for p in ignore_paths:
-                if path == p or path.relto(p):
-                    return True
-
     def consider(self, path):
-        if self._ignore(path):
+        if self.ihook.pytest_ignore_collect_path(path=path, config=self.config):
            return
         if path.check(file=1):
             res = self.consider_file(path)

testing/test_collect.py

@@ -157,6 +157,21 @@ class TestPrunetraceback:
         ])
 
 class TestCustomConftests:
+    def test_ignore_collect_path(self, testdir):
+        testdir.makeconftest("""
+            def pytest_ignore_collect_path(path, config):
+                return path.basename.startswith("x") or \
+                       path.basename == "test_one.py"
+        """)
+        testdir.mkdir("xy123").ensure("test_hello.py").write(
+            "syntax error"
+        )
+        testdir.makepyfile("def test_hello(): pass")
+        testdir.makepyfile(test_one="syntax error")
+        result = testdir.runpytest()
+        assert result.ret == 0
+        result.stdout.fnmatch_lines(["*1 passed*"])
+
     def test_collectignore_exclude_on_option(self, testdir):
         testdir.makeconftest("""
             collect_ignore = ['hello', 'test_world.py']